Subject: Cell division. Mitotic and life cycles Inactive portion of DNA in a cell

We all know that the appearance of a person, some habits and even diseases are inherited. All this information about a living being is encoded in the genes. So what do these notorious genes look like, how do they function, and where are they located?

So, the carrier of all genes of any person or animal is DNA. This compound was discovered in 1869 by Johann Friedrich Miescher. Chemically, DNA is deoxyribonucleic acid. What does this mean? How does this acid carry the genetic code of all life on our planet?

Let's start by looking at where DNA is located. There are many organelles in the human cell that perform various functions. DNA is located in the nucleus. The nucleus is a small organelle that is surrounded by a special membrane that stores all the genetic material - DNA.

What is the structure of a DNA molecule?

First, let's look at what DNA is. DNA is a very long molecule consisting of structural elements - nucleotides. There are 4 types of nucleotides - adenine (A), thymine (T), guanine (G) and cytosine (C). The chain of nucleotides schematically looks like this: GGAATTSTAAG.... This sequence of nucleotides is the DNA chain.

The structure of DNA was first deciphered in 1953 by James Watson and Francis Crick.

In one DNA molecule, there are two chains of nucleotides that are helically twisted around each other. How do these nucleotide chains stick together and twist into a spiral? This phenomenon is due to the property of complementarity. Complementarity means that only certain nucleotides (complementary) can be opposite each other in two chains. So, opposite adenine is always thymine, and opposite guanine is always only cytosine. Thus, guanine is complementary with cytosine, and adenine with thymine. Such pairs of nucleotides opposite each other in different chains are also called complementary.

It can be schematically represented as follows:

G - C
T - A
T - A
C - G

These complementary pairs A - T and G - C form chemical bond between the nucleotides of the pair, and the bond between G and C is stronger than between A and T. The bond is formed strictly between complementary bases, that is, the formation of a bond between non-complementary G and A is impossible.

The "packaging" of DNA, how does a strand of DNA become a chromosome?

Why do these nucleotide chains of DNA also twist around each other? Why is this needed? The fact is that the number of nucleotides is huge and you need a lot of space to accommodate such long chains. For this reason, there is a spiral twisting of two strands of DNA around the other. This phenomenon is called spiralization. As a result of spiralization, DNA chains are shortened by 5-6 times.

Some DNA molecules are actively used by the body, while others are rarely used. Such rarely used DNA molecules, in addition to helicalization, undergo even more compact “packaging”. Such a compact package is called supercoiling and shortens the DNA strand by 25-30 times!

How is DNA helix packaged?

For supercoiling, histone proteins are used, which have the appearance and structure of a rod or spool of thread. Spiralized strands of DNA are wound onto these "coils" - histone proteins. In this way, the long filament becomes very compactly packed and takes up very little space.

If it is necessary to use one or another DNA molecule, the process of “unwinding” occurs, that is, the DNA thread is “unwound” from the “coil” - the histone protein (if it was wound on it) and unwinds from the helix into two parallel chains. And when the DNA molecule is in such a untwisted state, then the necessary genetic information can be read from it. And reading genetic information occurs only with untwisted strands of DNA!

A set of supercoiled chromosomes is called heterochromatin, and the chromosomes available for reading information - euchromatin.

What are genes, what is their relationship with DNA?

Now let's look at what genes are. It is known that there are genes that determine the blood group, the color of the eyes, hair, skin and many other properties of our body. A gene is a strictly defined section of DNA, consisting of a certain number of nucleotides arranged in a strictly defined combination. Location in a strictly defined section of DNA means that a particular gene has its place, and it is impossible to change this place. It is appropriate to make such a comparison: a person lives on a certain street, in a certain house and apartment, and a person cannot arbitrarily move to another house, apartment or to another street. A certain number of nucleotides in a gene means that each gene has a specific number of nucleotides and cannot become more or less. For example, the gene encoding insulin production is 60 base pairs long; the gene encoding the production of the hormone oxytocin is 370 bp.

A strict nucleotide sequence is unique for each gene and strictly defined. For example, the AATTAATA sequence is a fragment of a gene that codes for insulin production. In order to obtain insulin, just such a sequence is used; to obtain, for example, adrenaline, a different combination of nucleotides is used. It is important to understand that only a certain combination of nucleotides encodes a certain "product" (adrenaline, insulin, etc.). Such a unique combination of a certain number of nucleotides, standing in "its place" - this is gene.

In addition to genes, the so-called "non-coding sequences" are located in the DNA chain. Such non-coding nucleotide sequences regulate the functioning of genes, help chromosome spiralization, and mark the start and end points of a gene. However, to date, the role of most non-coding sequences remains unclear.

What is a chromosome? sex chromosomes

The totality of an individual's genes is called the genome. Naturally, the entire genome cannot be packed into a single DNA. The genome is divided into 46 pairs of DNA molecules. One pair of DNA molecules is called a chromosome. So it is precisely these chromosomes that a person has 46 pieces. Each chromosome carries a strictly defined set of genes, for example, the 18th chromosome contains genes encoding eye color, etc. Chromosomes differ from each other in length and shape. The most common forms are in the form of X or Y, but there are also others. A person has two chromosomes of the same shape, which are called paired (pairs). In connection with such differences, all paired chromosomes are numbered - there are 23 pairs. This means that there is a pair of chromosomes #1, pair #2, #3, and so on. Each gene responsible for a particular trait is located on the same chromosome. In modern manuals for specialists, the localization of the gene may be indicated, for example, as follows: chromosome 22, long arm.

What are the differences between chromosomes?

How else do chromosomes differ from each other? What does the term long arm mean? Let's take X-shaped chromosomes. The crossing of DNA strands can occur strictly in the middle (X), or it can occur not centrally. When such an intersection of DNA strands does not occur centrally, then relative to the point of intersection, some ends are longer, others, respectively, are shorter. Such long ends are commonly called the long arm of the chromosome, and short ends, respectively, the short arm. Y-shaped chromosomes are mostly occupied by long arms, and short ones are very small (they are not even indicated on the schematic image).

The size of the chromosomes fluctuates: the largest are the chromosomes of pairs No. 1 and No. 3, the smallest chromosomes of pairs No. 17, No. 19.

In addition to shapes and sizes, chromosomes differ in their functions. Out of 23 pairs, 22 pairs are somatic and 1 pair is sexual. What does it mean? Somatic chromosomes determine all the external signs of an individual, the characteristics of his behavioral reactions, hereditary psychotype, that is, all the features and characteristics of each individual person. A pair of sex chromosomes determines the sex of a person: male or female. There are two types of human sex chromosomes - X (X) and Y (Y). If they are combined as XX (x - x) - this is a woman, and if XY (x - y) - we have a man in front of us.

Hereditary diseases and chromosome damage

However, there are "breakdowns" of the genome, then genetic diseases are detected in people. For example, when there are three chromosomes in 21 pairs of chromosomes instead of two, a person is born with Down syndrome.

There are many smaller "breakdowns" of the genetic material that do not lead to the onset of the disease, but, on the contrary, give good properties. All "breakdowns" of the genetic material are called mutations. Mutations that lead to disease or deterioration of the properties of the organism are considered negative, and mutations that lead to the formation of new beneficial properties are considered positive.

However, in relation to most of the diseases that people suffer today, it is not a disease that is inherited, but only a predisposition. For example, in the father of a child, sugar is absorbed slowly. This does not mean that the child will be born with diabetes, but the child will have a predisposition. This means that if a child abuses sweets and flour products, then he will develop diabetes.

Today, the so-called predicative the medicine. As part of this medical practice, predispositions are identified in a person (based on the identification of the corresponding genes), and then recommendations are given to him - what diet to follow, how to properly alternate the regime of work and rest so as not to get sick.

How to read the information encoded in DNA?

But how can you read the information contained in DNA? How does her own body use it? DNA itself is a kind of matrix, but not simple, but encoded. To read information from the DNA matrix, it is first transferred to a special carrier - RNA. RNA is chemically ribonucleic acid. It differs from DNA in that it can pass through the nuclear membrane into the cell, while DNA lacks this ability (it can only be found in the nucleus). The encoded information is used in the cell itself. So, RNA is a carrier of coded information from the nucleus to the cell.

How does RNA synthesis occur, how is protein synthesized with the help of RNA?

The DNA strands from which information must be “read” are untwisted, a special enzyme, the “builder”, approaches them and synthesizes a complementary RNA chain in parallel with the DNA strand. The RNA molecule also consists of 4 types of nucleotides - adenine (A), uracil (U), guanine (G) and cytosine (C). In this case, the following pairs are complementary: adenine - uracil, guanine - cytosine. As you can see, unlike DNA, RNA uses uracil instead of thymine. That is, the “builder” enzyme works as follows: if it sees A in the DNA strand, then it attaches Y to the RNA strand, if G, then it attaches C, etc. Thus, a template is formed from each active gene during transcription - a copy of RNA that can pass through the nuclear membrane.

How is the synthesis of a protein encoded by a particular gene?

After leaving the nucleus, RNA enters the cytoplasm. Already in the cytoplasm, RNA can be, as a matrix, built into special enzyme systems (ribosomes), which can synthesize, guided by the information of RNA, the corresponding amino acid sequence of the protein. As you know, a protein molecule is made up of amino acids. How does the ribosome manage to know which amino acid to attach to the growing protein chain? This is done on the basis of a triplet code. The triplet code means that the sequence of three nucleotides of the RNA chain ( triplet, for example, GGU) code for one amino acid (in this case glycine). Each amino acid is encoded by a specific triplet. And so, the ribosome “reads” the triplet, determines which amino acid should be added next as information is read into the RNA. When a chain of amino acids is formed, it takes a certain spatial form and becomes a protein capable of carrying out enzymatic, building, hormonal and other functions assigned to it.

Protein for any living organism is a gene product. It is proteins that determine all the various properties, qualities and external manifestations genes.

Task 1 Structure of chromosomes

When are chromosomes visible in the nucleus of a cell?

Task 2 Cell life cycle

Look at the picture and answer the questions:

What periods of interphase are indicated by numbers 1 - 3? What is the set of chromosomes and DNA in different periods of interphase? What periods of mitosis are indicated by numbers 4 - 7? What is the set of chromosomes and DNA in different periods of mitosis?

Task 3. Mitotic cycle

Fill the table:

periods of interphase and mitosis

ongoing processes

Number of chromosomes (n)

and the amount of DNA (s)

Presynthetic (G1)

Synthetic (S)

Postsynthetic (G2)

metaphase

Telophase

Task 4. Mitotic cycle

Test 1 During what period of the mitotic cycle does the amount of DNA double?

1. In the presynthetic period.

2. In the synthetic period.

4. In metaphase.

Test 2 During what period does cell growth take place?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 3 At what period of the life cycle does a cell have a set of chromosomes and DNA 2n4c and is preparing for division?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 4 During what period of the mitotic cycle does the spiralization of chromosomes begin, the nuclear envelope dissolves?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 5 During what period of the mitotic cycle do chromosomes line up along the equator of the cell?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 6 During what period of the mitotic cycle do chromatids move away from each other and become independent chromosomes?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 7 In what periods of mitosis is the number of chromosomes and DNA equal to 2n4c?

1. In prophase.

2. In metaphase.

3. Anaphase.

4. In telophase.

Test 8 At what period of mitosis is the number of chromosomes and DNA equal to 4n4c?

1. In prophase.

2. In metaphase.

3. Anaphase.

4. In telophase.

Test 9 What is the inactive part of DNA in a cell called?

1. Chromatin.

2. Euchromatin.

3. Heterochromatin.

4. All DNA in the cell is active.

Test 10 What are chromosomes called during interphase?

1. Chromatin.

2. Euchromatin.

3. Heterochromatin.

4. Chromosomes.

Task 5. Mitosis

Give answers to the questions:

1. What is a diploid set of chromosomes?

2. What is a haploid set of chromosomes?

3. What is the set of chromosomes and DNA in the presynthetic period of interphase?

4. What is the set of chromosomes and DNA in the postsynthetic period of interphase?

5. What is the set of chromosomes and DNA in the prophase and metaphase of mitosis?

6. What is the set of chromosomes and DNA in the anaphase of mitosis?

7. What is the set of chromosomes and DNA in the telophase of mitosis?

8. How many DNA molecules are in the nucleus of a human somatic cell before mitosis?

9. How many DNA molecules are in the nucleus of a human somatic cell after mitosis?

10. What are the names of chromosomes in the interphase period?

Task 6. Give definitions or expand concepts:

1. Interphase. 2. Chromatin. 3. Chromosome. 4. Chromatids. 5. Centromere. 6. Prophase. 7. Metaphase. 8. Anaphase. 9. Telophase. 10. Diploid set of chromosomes.

Subject: Cell division. Meiosis

Task 7. The first and second divisions of meiosis

Look at the picture and answer the questions:

What is the set of chromosomes and DNA in cells before the first division of meiosis? What is the set of chromosomes and DNA in cells at different periods of the first division of meiosis? What is the set of chromosomes and DNA in cells before the second division of meiosis? What is the set of chromosomes and DNA in cells at different periods of the second division of meiosis? At what stage of meiosis do conjugation and crossing of chromosomes take place? In meiosis, the genetic material is recombined three times. When? What is the biological meaning of meiosis?

Task 8. Meiosis

Fill the table:

divisions of meiosis	ongoing processes	Number of chromosomes (n) and the amount of DNA (s)
Prophase-1 Metaphase-1 Anaphase-1 Telophase-1
Interphase
Prophase-2 Metaphase-2 Anaphase-2 Telophase-2

Task 9. Meiosis

Specify the correct answers:

Test 1 When does conjugation of homologous chromosomes occur during meiosis?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 2 What is the set of chromosomes and DNA at the end of the 1st division of meiosis?

1. 1n1c. 5. 2n4c.

2. 1n2c. 6.4n4c.

Test 3 What is the set of chromosomes and DNA at the end of the 2nd division of meiosis?

1. 1n1c. 5. 2n4c.

2. 1n2c. 6.4n4c.

Test 4 In what stages of meiosis is the set of chromosomes and DNA 1n4c?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 5 In what stages of meiosis is the set of chromosomes and DNA 2n4c?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 6 In what stages of meiosis is the set of chromosomes and DNA 1n2c?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 7 In what stages of meiosis is the set of chromosomes and DNA 2n2c?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 8 In what stages of meiosis is the set of chromosomes and DNA 1n1c?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

***Test 9. During what stages of meiosis does recombination of genetic material take place?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Test 10 During what stages of meiosis does crossing over occur?

1. Prophase Prophase 2.

2. MetaphaseMetaphase 2.

3. AnaphaseAnaphase 2.

4. TelophaseTelophase 2.

Task 10. Meiosis

Give answers to the questions:

1. What is the set of chromosomes and DNA before the first division of meiosis?

2. What is the set of chromosomes and DNA before the second division of meiosis?

3. What chromosomes are called homologous?

4. What processes occur in prophase-1 of meiosis?

5. In what phases of the first division of meiosis does the recombination of genetic material occur?

6. What is characteristic of the interphase between the first and second divisions of meiosis?

7. What is the set of chromosomes and DNA in prophase-2 and metaphase-2?

8. In what phase of the second meiotic division does the recombination of genetic material occur?

9. What is the set of chromosomes and DNA at the end of the second meiotic division?

10. How many cells are formed as a result of meiosis from one mother cell?

Task 11. Give definitions or expand concepts:

1. Homologous chromosomes. 2. Conjugation. 3. Crossing over. 4. Diploid set of chromosomes. 5. Haploid set of chromosomes. 6. Reduction division of meiosis. 7. Recombination to anaphaseRecombination to anaphaseBiological meaning of meiosis.

Topic: Asexual and sexual reproduction

Task 12. Various forms of asexual reproduction

Look at the picture and answer the questions:

What forms of asexual reproduction are indicated in the figure by numbers 1 - 6? What genetic material do the offspring have during asexual reproduction?

Task 13. Characteristics of various forms of asexual reproduction

Fill the table:

Forms of asexual

breeding

Characteristics

1. Asexual reproduction of bacteria

2. Binary division

3. Shizogony

4. Sporulation

5. Budding

6. Fragmentation

7. Vegetative propagation

8. Polyembryony

9. Cloning

Task 14. Comparison of asexual and sexual reproduction

Fill the table:

Comparable Features

asexual reproduction

sexual reproduction

1. The number of individuals involved in reproduction

2. Genetic material of offspring

3. Recombination of genetic material

4. Importance for selection

Task 15. Asexual and sexual reproduction

Specify the correct answers:

Test 1 What form of asexual reproduction is most typical for mosses and ferns?

Test 2 What form of asexual reproduction is most typical for hydra, yeast?

1. Binary division. 5. Cloning.

2. Shizogony. 6. Vegetative propagation.

3. Fragmentation. 7. Polyembryony.

4. Budding. 8. Sporulation.

Test 3 What form of asexual reproduction is used to propagate fruit and berry crops?

1. Binary division. 5. Cloning.

2. Shizogony. 6. Vegetative propagation.

3. Fragmentation. 7. Polyembryony.

4. Budding. 8. Sporulation.

Test 4 What natural form of asexual reproduction is known in humans?

1. Binary division. 5. Cloning.

2. Shizogony. 6. Vegetative propagation.

3. Fragmentation. 7. Polyembryony.

4. Budding. 8. Sporulation.

Test 5 What form of asexual reproduction is typical for planaria, some annelids?

1. Binary division. 5. Cloning.

2. Shizogony. 6. Vegetative propagation.

3. Fragmentation. 7. Polyembryony.

4. Budding. 8. Sporulation.

Test 6 What is characteristic of asexual reproduction?

1. The offspring has the genes of only one, the mother's organism.

2. Offspring are genetically different from parental organisms.

3. One individual participates in the formation of offspring.

4. Two individuals usually participate in the formation of offspring.

Test 7 What form of reproduction allows you to adapt to changing environmental conditions?

1. Asexual reproduction.

2. Sexual reproduction.

3. And asexual and sexual reproduction equally.

4. The form of reproduction does not matter.

**Test 8. Specify the correct statements:

1. Parthenogenesis is a special form of asexual reproduction.

2. Parthenogenesis is a special form of sexual reproduction.

3. Parthenogenetic development is known in aphids, bees, and daphnia.

4. Parthenogenetic development is known in humans.

**Test 9. Specify the correct statements:

1. Hermaphrodites - organisms that can form both male and female gametes.

2. Gametes have a haploid set of chromosomes, the zygote is diploid.

3. developed methods for targeted production of 100% individuals of the same sex.

4. Bacteria divide by mitosis.

**Test 10. Specify the correct statements:

1. Asexual reproduction has no advantages over sexual reproduction.

2. Gametes and zygote have a haploid set of chromosomes.

3. Two individuals always take part in sexual reproduction.

4. Sexual reproduction dramatically increases the hereditary variability of offspring.

Topic: The formation of germ cells and fertilization

Task 16. Gametogenesis

Look at the picture and answer the questions:

1. *** What is indicated in the figure by numbers 1 - 12?

2. What is the size of an egg in humans?

3. What is in the cytoplasm of the egg?

4. Where are the nucleus and mitochondria located in the spermatozoon?

Task 18. Gametogenesis. Fertilization

Specify the correct answers:

Test 1 What set of chromosomes do the precursors of gametes have in the breeding zone?

1. Diploid.

2. Haploid.

3. Spermatogonia are diploid, ovogonia are haploid.

4. Spermatogonia are haploid, ovogonia are diploid.

Test 2 What set of chromosomes do cells have in the maturation zone after the first division of meiosis?

Test 3 What set of chromosomes do gametes have?

Test 4 How many normal eggs are produced from one oocyte after two divisions of meiosis?

Test 5 How many normal spermatozoa are formed from one spermatocyte after two divisions of meiosis?

Test 6 Where is the Golgi complex located in the spermatozoon?

1. In the head.

2. In the neck.

3. In the intermediate department.

4. In the ponytail.

Test 7 Where are the mitochondria located in the sperm?

1. In the head.

2. In the neck.

3. In the intermediate department.

4. In the ponytail.

Test 8 Where are the centrioles located in the spermatozoon?

1. In the head.

2. In the neck.

3. In the intermediate department.

4. In the ponytail.

**Test 9. Specify the correct statements:

1. In the growth zone, the chromosome set is 2n.

2. In the zone of maturation, two divisions of meiosis occur - reduction and equational.

3. During oogenesis, four normal eggs are formed from one oocyte.

4. During oogenesis, one normal egg and four directional (polar) bodies are formed from one oocyte.

***Test 10. Specify the correct statements:

1. The human egg is about 0.1 mm in size.

2. Human eggs are formed at the embryonic stage.

3. The human egg has two shells - shiny and radiant.

4. There are no ribosomes and mitochondria in the human egg.

Topic: Individual development of organisms

Task 19. The main stages of embryogenesis

Look at the picture and answer the questions:

*** What is indicated in the figure by the numbers 1 - 10? What is formed as a result of zygote cleavage? *** What is further formed from the blastocoel? What is the name of the hole in the gastrula? What germ layer does the neural tube develop from? What is the name of an embryo with a formed axial complex? What happens if we take a portion of the ectoderm from which the nervous system is formed from one gastrula and transplant it under the abdominal ectoderm of another gastrula?

Task 20. Derivatives of germ layers

Fill the table:

germ layers	Derivatives of the germ layers
ectoderm
Endoderm
mesoderm

Task 21. Ontogeny

Specify the correct answers:

Test 1.What is formed as a result of complete crushing of the zygote?

1. Neirula.

2. Blastula.

3. Gastrula.

4. Morula.

Test 2. What is the name of the cavity inside the blastula?

1. Blastocoel.

2. Gastrocoel.

3. Secondary body cavity.

Test 3. What is the name of a two-layer embryo with germ layers: ectoderm and endoderm?

1. Gastrula.

2. Blastula.

3. Neirula.

4. Morula.

Test 4. What is the name of the cavity into which the primary mouth leads?

1. Blastocoel.

2. Gastrocoel.

3. Secondary body cavity.

4. Mixed body cavity (myxocoel).

Test 5. What organisms are classified as deuterostomes?

1. Coelenterates and sponges.

2. Flat and roundworms.

3. Mollusks and arthropods.

4. Echinoderms and chordates.

Test 6. What is the name of an embryo with an axial complex of organs?

1. Gastrula.

2. Blastula.

3. Neirula.

4. Morula.

Test 7. Specify derivatives of ectoderm:

Test 8. Specify derivatives of endoderm:

1. The epidermis of the skin. 6. Digestive system.

2. Epithelium of the digestive system. 7. Digestive glands.

3. Circulatory system. 8. Respiratory system.

4. Excretory system. 9. Reproductive system.

5. Nervous system. 10. Sense organs.

Test 9. Specify derivatives of mesoderm:

1. The epidermis of the skin. 6. Digestive system.

2. Epithelium of the digestive system. 7. Digestive glands.

3. Circulatory system. 8. Respiratory system.

4. Excretory system. 9. Reproductive system.

5. Nervous system. 10. Sense organs.

Test 10 Specify animals with indirect postembryonic development:

1. Mammals. 5. Butterflies.

2. Birds. 6. Locust.

3. Reptiles. 7. Spiders.

4. Amphibians. 8. Cockroaches.

Task 22. Ontogeny

Biological dictation:

1. What is the name of the individual development of the organism from the formation of a zygote to the end of life?

2. What is the name of the development of the organism from the zygote to birth or to release from the egg membranes?

3. What is the name of the period from birth to the end of life?

4. How does the crushing period end?

5. What is the name of an embryo with three germ layers: ectoderm, endoderm and mesoderm?

6. What organisms are deuterostomes?

7. What is the name of the embryo in which the axial complex of organs has formed?

8. What organ systems are formed from the ectoderm?

9. Specify endoderm derivatives.

10. Write down two types of animals with direct and indirect types of postembryonic development.

Task 23. Give definitions or expand concepts:

1. Fertilization. 2. Zygote. 3. Blastomeres. 4. Blastula. 5. Blastocoel (primary cavity). 6. Gastrula. 7. Mesoderm. 8. Secondary mouth. 9. Neirula. 10. Indirect postembryonic development.

Used materials, Honored School Teacher of the Russian Federation; , Ph.D.

Subject: Cell division. Mitosis Task 4.1 Structure of chromosomes

Task 4.2 Cell life cycle

Look at the picture and answer the questions:

What periods of interphase are indicated by numbers 1 - 3?

What is the set of chromosomes and DNA in different periods of interphase?

What periods of mitosis are indicated by numbers 4 - 7?

What is the set of chromosomes and DNA in different periods of mitosis?

Task 4.3. Mitotic cycle

Fill the table:

periods of interphase and mitosis

ongoing processes

Number of chromosomes (n)

and the amount of DNA (s)

Presynthetic (G 1)

Synthetic (S)

Postsynthetic (G 2)

metaphase

Telophase

Task 4.4. Mitotic cycle

Test 1 During what period of the mitotic cycle does the amount of DNA double?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 2 During what period does cell growth take place?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 3 At what period of the life cycle does a cell have a set of chromosomes and DNA 2n4c and is preparing for division?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 4 During what period of the mitotic cycle does the spiralization of chromosomes begin, the nuclear envelope dissolves?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 5 During what period of the mitotic cycle do chromosomes line up along the equator of the cell?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 6 During what period of the mitotic cycle do chromatids move away from each other and become independent chromosomes?

During the presynthetic period.

in the synthetic period.

in the post-synthetic period.

In metaphase.

Test 7 In what periods of mitosis is the number of chromosomes and DNA equal to 2n4c?

In prophase.

In metaphase.

In anaphase.

In telophase.

Test 8 At what period of mitosis is the number of chromosomes and DNA equal to 4n4c?

In prophase.

In metaphase.

In anaphase.

In telophase.

Test 9 What is the inactive part of DNA in a cell called?

Chromatin.

Euchromatin.

Heterochromatin.

All DNA in a cell is active.

Test 10 What are chromosomes called during interphase?

Chromatin.

Euchromatin.

Heterochromatin.

Chromosomes.

Task 4.5. Mitosis

Give answers to the questions:

What is a diploid set of chromosomes?

What is a haploid set of chromosomes?

What is the set of chromosomes and DNA in the presynthetic period of interphase?

What is the set of chromosomes and DNA in the postsynthetic period of interphase?

What is the set of chromosomes and DNA in the prophase and metaphase of mitosis?

What is the set of chromosomes and DNA in the anaphase of mitosis?

What is the set of chromosomes and DNA in the telophase of mitosis?

How many DNA molecules are in the nucleus of a human somatic cell before mitosis?

How many DNA molecules are in the nucleus of a human somatic cell after mitosis?

What are the chromosomes called during interphase?

Task 4.6. Give definitions or expand concepts:

1. Interphase. 2. Chromatin. 3. Chromosome. 4. Chromatids. 5. Centromere. 6. Prophase. 7. Metaphase. 8. Anaphase. 9. Telophase. 10. Diploid set of chromosomes.

Subject: Cell division. Meiosis Task 4.7. First and second divisions of meiosis

Look at the picture and answer the questions:

What is the set of chromosomes and DNA in cells before the first division of meiosis?

What is the set of chromosomes and DNA in cells at different periods of the first division of meiosis?

What is the set of chromosomes and DNA in cells before the second division of meiosis?

What is the set of chromosomes and DNA in cells at different periods of the second division of meiosis?

At what stage of meiosis do conjugation and crossing of chromosomes take place?

In meiosis, the genetic material is recombined three times. When?

What is the biological meaning of meiosis?

Task 4.8. Meiosis

Fill the table:

divisions of meiosis	ongoing processes	Number of chromosomes (n) and the amount of DNA (s)
Prophase-1 Metaphase-1 Anaphase-1 Telophase-1
Interphase
Prophase-2 Metaphase-2 Anaphase-2 Telophase-2

Task 4.9. Meiosis

Specify the correct answers:

Test 1 When does conjugation of homologous chromosomes occur during meiosis?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 2 What is the set of chromosomes and DNA at the end of the 1st division of meiosis?

Test 3 What is the set of chromosomes and DNA at the end of the 2nd division of meiosis?

Test 4 In what stages of meiosis is the set of chromosomes and DNA 1n4c?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 5 In what stages of meiosis is the set of chromosomes and DNA 2n4c?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 6 In what stages of meiosis is the set of chromosomes and DNA 1n2c?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 7 In what stages of meiosis is the set of chromosomes and DNA 2n2c?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 8 In what stages of meiosis is the set of chromosomes and DNA 1n1c?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

***Test 9. During what stages of meiosis does recombination of genetic material take place?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Test 10 During what stages of meiosis does crossing over occur?

Prophase 1. 5. Prophase 2.

Metaphase 1. 6. Metaphase 2.

Anaphase 1. 7. Anaphase 2.

Telophase 1. 8. Telophase 2.

Task 4.10. Meiosis

Give answers to the questions:

What is the set of chromosomes and DNA before the first division of meiosis?

What is the set of chromosomes and DNA before the second division of meiosis?

What chromosomes are called homologous?

What processes occur in prophase 1 of meiosis?

In what phases of the first division of meiosis does the recombination of genetic material occur?

What is the set of chromosomes and DNA in prophase-2 and metaphase-2?

In what phase of the second meiotic division does the recombination of genetic material take place?

What is the set of chromosomes and DNA at the end of the second meiotic division?

How many cells are formed as a result of meiosis from one parent cell?

Task 4.11. Give definitions or expand concepts:

1. Homologous chromosomes. 2. Conjugation. 3. Crossing over. 4. Diploid set of chromosomes. 5. Haploid set of chromosomes. 6. Reduction division of meiosis. 7. Recombination to anaphase-1. 8. Recombination to anaphase-2. 9. The biological meaning of meiosis.

Topic: Asexual and sexual reproduction Task 4.12. Various forms of asexual reproduction

Look at the picture and answer the questions:

What forms of asexual reproduction are indicated in the figure by numbers 1 - 6?

What genetic material do the offspring have during asexual reproduction?

Task 4.13. Characteristics of various forms of asexual reproduction

Fill the table:

Task 4.14. Comparison of asexual and sexual reproduction

Fill the table:

Comparable Features	asexual reproduction	sexual reproduction
The number of individuals involved in reproduction offspring genetic material Recombination of genetic material Selection value

Task 4.15. Asexual and sexual reproduction

Specify the correct answers:

Test 1 What form of asexual reproduction is most typical for mosses and ferns?

Test 2 What form of asexual reproduction is most typical for hydra, yeast?

binary division. 5. Cloning.

Schizogony. 6. Vegetative reproduction.

Fragmentation. 7. Polyembryony.

Budding. 8. Sporulation.

Test 3 What form of asexual reproduction is used to propagate fruit and berry crops?

binary division. 5. Cloning.

Schizogony. 6. Vegetative reproduction.

Fragmentation. 7. Polyembryony.

Budding. 8. Sporulation.

Test 4 What natural form of asexual reproduction is known in humans?

binary division. 5. Cloning.

Schizogony. 6. Vegetative reproduction.

Fragmentation. 7. Polyembryony.

Budding. 8. Sporulation.

Test 5 What form of asexual reproduction is typical for planaria, some annelids?

binary division. 5. Cloning.

Schizogony. 6. Vegetative reproduction.

Fragmentation. 7. Polyembryony.

Budding. 8. Sporulation.

Test 6

Offspring have the genes of only one, the mother's organism.

The offspring are genetically different from the parent organisms.

One individual participates in the formation of offspring.

Two individuals usually participate in the formation of offspring.

Test 7 What form of reproduction allows you to adapt to changing environmental conditions?

Asexual reproduction.

Sexual reproduction.

Both asexual and sexual reproduction equally.

The form of reproduction does not matter.

**Test 8. Specify the correct statements:

Parthenogenesis is a special form of asexual reproduction.

Parthenogenesis is a special form of sexual reproduction.

Parthenogenetic development is known in aphids, bees, and daphnia.

Parthenogenetic development is known in humans.

**Test 9. Specify the correct statements:

Hermaphrodites are organisms that can form both male and female gametes.

The gametes have a haploid set of chromosomes, the zygote is diploid.

B.L. Astaurov developed methods for the targeted production of 100% of individuals of the same sex.

Bacteria divide by mitosis.

**Test 10. Specify the correct statements:

Asexual reproduction has no advantages over sexual reproduction.

Gametes and zygote have a haploid set of chromosomes.

Two individuals always take part in sexual reproduction.

Sexual reproduction sharply increases the hereditary variability of offspring.

Topic: Formation of germ cells and fertilization Task 4.16. Gametogenesis

Look at the picture and answer the questions:

What is indicated in the figure by the numbers 1 - 6?

What is the set of chromosomes in the breeding zone, where the precursors of gametes divide mitotically?

What is the set of chromosomes in the growth zone before the first division of meiosis?

What is the set of chromosomes and DNA after the first division of meiosis? After the second division?

How many normal eggs are formed from one oocyte entering meiosis?

Task 4.17. The structure of germ cells

Look at the picture and answer the questions:

*** What is indicated in the figure by numbers 1 - 12?

What is the size of a human egg?

What is in the cytoplasm of the egg?

Where are the nucleus and mitochondria located in the spermatozoon?

Task 4.18. Gametogenesis. Fertilization

Specify the correct answers:

Test 1 What set of chromosomes do the precursors of gametes have in the breeding zone?

diploid.

Haploid.

Spermatogonia are diploid, ovogonia are haploid.

Spermatogonia are haploid, ovogonia are diploid.

Test 2 What set of chromosomes do cells have in the maturation zone after the first division of meiosis?

Test 3 What set of chromosomes do gametes have?

Test 4 How many normal eggs are produced from one oocyte after two divisions of meiosis?

Test 5 How many normal spermatozoa are formed from one spermatocyte after two divisions of meiosis?

Test 6 Where is the Golgi complex located in the spermatozoon?

In the head.

In the intermediate section.

In the ponytail.

Test 7 Where are the mitochondria located in the sperm?

In the head.

In the intermediate section.

In the ponytail.

Test 8 Where are the centrioles located in the spermatozoon?

In the head.

In the intermediate section.

In the ponytail.

**Test 9. Specify the correct statements:

In the growth zone, the chromosome set is 2n.

In the maturation zone, two divisions of meiosis occur - reduction and equational.

Oogenesis produces four normal eggs from one oocyte.

During oogenesis, one normal egg and four directional (polar) bodies are formed from one oocyte.

***Test 10. Specify the correct statements:

The human egg is about 0.1 mm in size.

Human eggs are formed at the embryonic stage.

The human egg has two shells - shiny and radiant.

The human egg lacks ribosomes and mitochondria.

Task 4.19. Double fertilization of flowering plants

Look at the picture and answer the questions:

*** What is indicated in the figure by the numbers 1 - 21?

Where are the microspores of flowering plants formed?

*** What is formed from integuments? From the walls of the ovary?

***Task 4.20. Double fertilization of flowering plants

Specify the correct answers:

Test 1 How many ovules can be in a pistil?

Always alone.

Usually equal to the number of seeds.

Usually equal to the number of fruits.

Equal to the number of pestles.

Test 2 A flower is an organ of asexual and sexual reproduction. What is asexual reproduction?

in the formation of seeds.

in fruit formation.

In the formation of dispute.

in the formation of gametes.

Test 3 What parts of a flower form a perianth?

A calyx of sepals.

A corolla of petals.

Cup and whisk.

Calyx, corolla, androecium and gynoecium.

Test 4 What is the male gametophyte of flowering plants?

A collection of stamens.

Pollen bag.

Microspore.

Pollen grain.

Test 5 What is the female gametophyte of flowering plants?

Pestle.

The ovary of the pestle.

Ovule.

Embryonic sac.

Test 6 What is produced from a fertilized egg?

The germ of the seed.

Endosperm.

Test 7 What is formed from the fertilized central cell?

The germ of the seed.

Endosperm.

Test 8 What is formed from integuments?

Pericarp.

Testa.

Endosperm.

Cotyledons.

Test 9 What is the pericarp formed from?

From integuments.

From the walls of the ovary.

From pestle.

From the flower bed.

Test 10 Who discovered double fertilization

S.G. Navashin.

I.V. Michurin.

N.I.Vavilov.

G. Mendel.

Task 4.21. Double fertilization of flowering plants

Give answers to the questions:

What is the set of chromosomes in the somatic cells of a flowering plant?

What is the male gametophyte of flowering plants?

How many cells are in a mature male gametophyte, what are they called?

What is the female gametophyte of flowering plants?

How many cells are in a mature female gametophyte, what are they called?

What is produced from a fertilized egg?

What is formed from the fertilized central cell?

What is formed from integuments (covers of the ovule)?

What is formed from the walls of the ovary?

What is formed from the ovule?

What is formed from the ovary of the pistil?

Who discovered double fertilization in flowering plants?

Task 4.22. Give definitions or expand concepts:

1. Sporophyte of flowering plants. 2. Flower. ***3. Androecium. ***four. Gynoecium. ***5. The male gametophyte of flowering plants. ***6. The female gametophyte of flowering plants. 7. Double fertilization of flowering plants. 8. Endosperm. 9. Seed germ. 10. Sperm. ***eleven. Integuments. 12. Micropyle. ***13. Nucellus. 14. Ovule.

Topic: Individual development of organisms Task 4.23. The main stages of embryogenesis

Look at the picture and answer the questions:

*** What is indicated in the figure by the numbers 1 - 10?

*** What is further formed from the blastocoel?

What is the name of the hole in the gastrula?

What germ layer does the neural tube develop from?

What is the name of an embryo with a formed axial complex?

What happens if we take a portion of the ectoderm from which the nervous system is formed from one gastrula and transplant it under the abdominal ectoderm of another gastrula?

Task 4.24.

Fill the table:

germ layers	Derivatives of the germ layers
ectoderm
Endoderm
mesoderm

Task 4.25. Ontogenesis

Specify the correct answers:

Test 1.What is formed as a result of complete crushing of the zygote?

Blastula.

Gastrula.

Test 2. What is the name of the cavity inside the blastula?

Blastocoel.

Gastrocel.

Secondary body cavity.

Test 3. What is the name of a two-layer embryo with germ layers: ectoderm and endoderm?

Gastrula.

Blastula.

Test 4. What is the name of the cavity into which the primary mouth leads?

Blastocoel.

Gastrocel.

Secondary body cavity.

Mixed body cavity (myxocoel).

Test 5. What organisms are classified as deuterostomes?

Coelenterates and sponges.

Flat and round worms.

Mollusks and arthropods.

Echinoderms and chordates.

Test 6. What is the name of an embryo with an axial complex of organs?

Gastrula.

Blastula.

Test 7. Specify derivatives of ectoderm:

Test 8. Specify derivatives of endoderm:

Skin epidermis. 6. Digestive system.

Epithelium of the digestive system. 7. Digestive glands.

Circulatory system. 8. Respiratory system.

excretory system. 9. Reproductive system.

Nervous system. 10. Sense organs.

Test 9. Specify derivatives of mesoderm:

Skin epidermis. 6. Digestive system.

Epithelium of the digestive system. 7. Digestive glands.

Circulatory system. 8. Respiratory system.

excretory system. 9. Reproductive system.

Nervous system. 10. Sense organs.

Test 10 Specify animals with indirect postembryonic development:

Mammals. 5. Butterflies.

Birds. 6. Locust.

Reptiles. 7. Spiders.

Amphibians. 8. Cockroaches.

Task 4.26. Ontogenesis

Biological dictation:

What is the name of the individual development of an organism from the formation of a zygote to the end of life?

What is the development of an organism from zygote to birth or to release from the egg membranes called?

What is the period from birth to the end of life called?

What is the end of the crushing period?

What is the name of an embryo with three germ layers: ectoderm, endoderm and mesoderm?

What organisms are classified as deuterostomes?

What is the name of the embryo in which the axial complex of organs has formed?

What organ systems are formed from the ectoderm?

Specify derivatives of endoderm.

Write down two types of animals with direct and indirect type of postembryonic development.

Task 4.27. Give definitions or expand concepts:

1. Fertilization. 2. Zygote. 3. Blastomeres. 4. Blastula. 5. Blastocoel (primary cavity). 6. Gastrula. 7. Mesoderm. 8. Secondary mouth. 9. Neirula. 10. Indirect postembryonic development.

Task 4.28. Questions to set off:

What is the name of the set of chromosomes characteristic of a species?

What is the set of chromosomes in somatic and germ cells?

How many chromosomes and DNA are there in different periods of interphase?

What are paired, identical chromosomes of a somatic cell called?

What is the name of the primary constriction and the ends of the chromosome?

How many chromosomes and DNA are there in a cell before mitosis and at the end of mitosis?

How many chromosomes and DNA are in prophase, metaphase and anaphase of mitosis?

What is the meaning of meiosis?

What are the first and second divisions of meiosis called?

What processes occur in the cell during prophase 1 of meiosis?

How many chromosomes and DNA before meiosis, after the first and second division?

What is the set of chromosomes and DNA in metaphase 1 and anaphase 1 of meiosis?

What is characteristic of interphase between the first and second divisions of meiosis?

What is the set of chromosomes and DNA in metaphase 2 and anaphase 2 of meiosis?

When does recombination of genetic material take place in meiosis?

List the phases of meiosis during which the chromosomes are bichromatid.

What is characteristic of asexual reproduction?

What is the name of the division in which multiple division of the nucleus occurs and several individuals are formed (in trypanosomes, malarial plasmodium)?

What is characteristic of the genotypes of daughter individuals in comparison with the maternal one during asexual reproduction?

What set of chromosomes do spores have?

What are the membranes of a mammalian egg called?

When does oogenesis begin in humans?

What is the name of reproduction, in which the development of a new organism comes from an unfertilized egg?

What is the set of chromosomes in gametogonia? Gametocytes of the 1st order? 2-order gametocytes?

What is formed after spermatogenesis from one spermatocyte?

What is formed after oogenesis from 1 oocyte?

Which organisms have external fertilization?

What are the male and female gametophytes of flowering plants?

What is formed from the integuments and the central cell of the embryo sac?

What is the pericarp formed from?

Who discovered double fertilization?

What are the stages of animal ontogeny?

What are the stages of animal embryogenesis?

What is formed as a result of zygote cleavage?

What is the name of the two-layer embryo of the lancelet?

What is formed from the ectoderm, endoderm and mesoderm of the neurula?

What germ layers form the spine, epidermis and lungs?

What animals are classified as deuterostomes?

Write three animals with direct postembryonic development.

Write three animals with indirect postembryonic development.

Answers on questions

Task 4.1.

1 - equal-arm (metacentric) chromosomes; 2 - uneven shoulders (submetacentric); 3 - sharply uneven shoulders (acrocentric); 4 - telocentric chromosomes, in which the primary constriction is in the telomere region; 5 - primary constriction, centromere; 6 - secondary constriction (nucleolar organizer); 7 - satellite; 8 - chromatids; 9 - telomeres.

Two chromatids, two DNA molecules.

during mitosis and meiosis.

2n - 46, n - 23.

Paired, identical chromosomes carrying the same genes.

***About 8 cm in the first chromosome.

***About 2 meters.

Task 4.2.

1 - presynthetic (G 1), 2 - postsynthetic (S), 3 - postsynthetic (G 2).

G 1 - 2n2c; at the end of the S-period - 2n4c; G2-2n4c.

4 - prophase, 5 - metaphase, 6 - anaphase, 7 - telophase.

Prophase - 2n4c, metaphase - 2n4c, anaphase - 4n4c, telophase - 2n2c.

Task 4.3.

periods of interphase and mitosis

ongoing processes

Number of chromosomes (n)

and the amount of DNA (s)

Presynthetic (G 1)

Synthetic (S)

Postsynthetic (G 2)

Active cell growth, synthesis of structural and functional proteins.

In mammalian cells, it lasts about 6-10 hours. DNA replication occurs. By the end of the period, each chromosome consists of two chromatids, two DNA molecules.

Mitochondria, plastids, centrioles double. Proteins and energy for division are accumulated.

metaphase

Telophase

DNA spiralization occurs, the chromosomes shorten and thicken, the nucleoli disappear, the centrioles diverge and the fission spindle is formed. The nuclear envelope breaks into fragments.

The chromatids are pulled apart to opposite poles, becoming independent chromosomes.

Chromosomes despiralize, the nuclear envelope is formed, the nucleolus appears, and the spindle microtubules disappear. There is a division of the cytoplasm, in animal cells by constriction, in plant cells a barrier is formed.

Task 4.4.

Test 1: 2. Test 2: 1. Test 3: 3. Test 4: 1. Test 5: 4. Test 6: 1. **Test 7: 1, 2.Test 8: 3. ***Test 9: 3. **Test 10: 3, 4, 5.

Task 4.5.

1. A double set of chromosomes is characteristic of somatic cells. 2. A single set of chromosomes, characteristic of germ cells. 3. 2n2c. 4. 2n4c. 5. 2n4c. 6.4n4c. 7. 2n2c. 8. 92 molecules. 9. 46. 10. Chromatin.

Task 4.6.

1. The period of time during which the cell is preparing for division. 2. Chromosomes in the interphase period. 3. Organelles of the cell nucleus, which are carriers of genes. 4. Structural elements of the chromosome, formed in the interphase as a result of DNA doubling. They are best seen during metaphase. 5. Part of the chromosome to which the microtubules of the division spindle are attached. 6. Initial period mitosis, in which the spiralization of chromosomes occurs, the dissolution of the nuclear membrane, the disappearance of the nucleolus, the divergence of centrioles and the formation of the division spindle. 7. The period of mitosis, during which the chromosomes line up in the plane of the equator of the cell, microtubules of the spindle are attached to the centromeres. 8. The period of mitosis, in which the chromatids diverge to the poles of the cell and become independent chromosomes. 9. During this period, the chromosomes decondense, nuclear membranes are formed and nucleoli appear, cytokinesis occurs - the division of the cytoplasm. 10. Double set of chromosomes.

Task 4.7.

1. 2n4c. 2. Prophase 1 - 2n4c, metaphase 1 - 2n4c, anaphase 1 - 2n4c, telophase 1 - n2c. 3.n2c. 4. Prophase 2 - n2c, metaphase 2 - n2c, anaphase 2 - 2n2c, telophase 2 - nc. 5. Into prophase 1. 6. Into prophase 1, into anaphase 1, into anaphase 2. 7. Reduction of the chromosome set to maintain the constancy of the number of chromosomes during generational change and recombination of genetic material.

Task 4.8.

divisions of meiosis	ongoing processes	Number of chromosomes (n) and the amount of DNA (s)
Prophase-1 Metaphase-1 Anaphase-1 Telophase-1	In addition to the usual processes characteristic of prophase, there is conjugation of homologous chromosomes and crossing over - an exchange of sections of homologous chromosomes. Homologous chromosomes remain connected in some areas and are located in the plane of the equator of the cell. Spindle microtubules are attached to the centromeres. Homologous chromosomes, consisting of two chromatids, are pulled apart to opposite poles, each pole has a haploid set of chromosomes. Secondary recombination of genetic material occurs. Chromosomes despiralize, a nuclear envelope is formed, and the cytoplasm divides.
Interphase	Short, no S-period.
Prophase-2 Metaphase-2 Anaphase-2 Telophase-2	Chromosomes shorten and thicken, centrioles diverge and the spindle is formed. The nuclear envelope is destroyed. Chromosomes are located in the plane of the equator of the cell. Spindle microtubules are attached to the centromeres. The chromatids are pulled apart to opposite poles, becoming independent chromosomes. Third recombination of genetic material. Chromosomes despiralize, the nuclear envelope is formed, the nucleolus appears, and the spindle microtubules disappear. The division of the cytoplasm takes place.

Task 4.9.

Test 1: 1. Test 2: 2. Test 3: 1. **Test 4: 1, 2, 3,. Test 5: 8. **Test 6: 4, 5, 6. Test 7: 7.Test 8: 8. Test 9: 1, 3, 7. Test 10: 1.

Task 4.10.

1. 2n4c. 2.n2c. 3. Paired, identical chromosomes carrying the same genes. 4. Conjugation and crossing over. 5. In prophase and anaphase. 6. There is no S-period. 7.n2c. 8. Anaphase 2. 9. nc. 10. Four.

Task 4.11.

1. Paired chromosomes, identical in size, shape, composition and order of genes. 2. The process of close approach of homologous chromosomes. 3. Exchange of sections of homologous chromosomes. 4. Double set of chromosomes. 5. Single set of chromosomes. 6. The first division of meiosis, which results in a reduction in the number of chromosomes. 7. Occurs as a result of the divergence of homologous chromosomes to different poles of the cell. At each pole, a random combination of paternal and maternal chromosomes is assembled. 8. As a result of crossing over, the chromatids in the chromosome began to differ from each other; as a result of anaphase, chromosomes that are unique in terms of the set of genes are assembled at each pole. 9. Reduction of the chromosome set to maintain the constancy of the number of chromosomes during the change of generations and recombination of genetic material during the formation of gametes or spores.

Task 4.12.

1 - binary division; 2 - schizogony, multiple division; 3 - budding; 4 - fragmentation; 5 - vegetative reproduction; 6 - reproduction by spores.

Usually identical to the genetic material of the parent.

They won't, each spore formed as a result of meiosis has a unique set of genes.

Task 4.13.

Forms of asexual reproduction

Characteristics

asexual reproduction of bacteria

Binary division

schizogony

sporulation

budding

Fragmentation

Vegetative propagation

Polyembryony

Cloning

Bisection, not mitosis, under favorable conditions occurs after 20 minutes.

mitotic division. Characteristic of protozoa and somatic cells of multicellular organisms.

Multiple division. Typical for protozoa and some algae.

Spores can be formed mitotically (for example, in mosses) and meiotically (for example, in ferns). In the second case, the disputes are genetically unequal.

It is characteristic of some fungi (for example, yeast), animals (for example, for freshwater hydra), some plants.

Reproduction, in which the body is divided into fragments, each of which regenerates the missing organs.

Propagation of plants by vegetative organs (root, leaves, shoots).

Development of several embryos from one zygote.

The ability to grow a genetically identical individual by transplanting a nucleus from a somatic cell into an egg from which the nucleus has previously been removed.

Task 4.14.

Comparable Features

asexual reproduction

sexual reproduction

1. The number of individuals involved in reproduction

2. Genetic material of offspring

3. Recombination of genetic material

4. Importance for selection

Offspring have the genes of only one, the mother's organism. The genetic material is usually the same as that of the parent.

Usually absent. Occurs if, for example, spores are formed as a result of meiosis.

Leads to a rapid increase in the number of genetically identical offspring.

Differs from the genetic material of the parent organisms.

Occurs during the formation of gametes and their random combination.

Provides genetically heterogeneous material for natural selection.

Task 4.15.

Test 1: 8. Test 2: 4. Test 3: 6. Test 4: 7. Test 5: 3. **Test 6: 1, 3. Test 7: 2.**Test 8: 2, 3. **Test 9: 1, 2, 3. Test 10: 4.

Task 4.16.

***1 - ovogonia; 2 - oocytes of the 1st order; 3 - oocytes of the 2nd order; 4 - the first guide body; 5 - egg; 6 - guide bodies of the 2nd order.

After the first division n2с, after the second - nс..

Task 4.17.

1 - chromosomes at the stage of metaphase 2. 2 - zona pellucida. 3 - radiant shell. 4 - the first guide body. 5 - the head of the spermatozoon. 6 - acrosome. 7 - core. 8 - centrioles. 9 - neck. 10 - mitochondria. 11 - intermediate department. 12 - flagellum.

About 0.1mm.

Even before birth, at the stage of the embryo.

The nucleus in the head, mitochondria in the intermediate section of the spermatozoon.

Task 4.18.

Test 1: 1. Test 2: 3. Test 3: 4. **Test 4: 1, 2, 4, 5. Test 5: 4. Test 6: 1. Test 7: 3.Test 8: 2. **Test 9: 1, 2, 4. **Test 10: 1, 2, 3.

Task 4.19.

***1 - peduncle; 2 - receptacle; 3 - sepals; 4 - corolla petals; 5 - filament; 6 - pollen bag; 7 - ovary of the pistil; 8 - ovules; 9 - integuments; 10 - micropyle; 11 - placenta; 12 - seed stalk; 13 - nucellus; 14 - egg; 15 - synergides; 16 - central cell; 17 - antipodes; 18 - chalaza; 19 - microsporangia; 20 - exine; 21 - intina; 22 - vegetative cell; 23 - generative cell; 24 - two sperm.

In microsporangia, in anther nests.

Pollen grain.

Embryonic sac.

The germ of the seed.

triploid endosperm.

From the integuments - the peel of the seed, from the walls of the ovary - the pericarp.

Task 4.20.

Test 1: 2. Test 2: 3. Test 3: 3. Test 4: 4. Test 5: 4. Test 6: 3. Test 7: 4.Test 8: 2. Test 9: 2. Test 10: 1.

Task 4.21.

1. Diploid. 2. Pollen grain. 3. Vegetative cell and two sperm. 4. Embryo sac. 5. Seven cells: an egg and two cells - synergids, a central cell and three cells - antipodes. 6. Seed germ. 7. Endosperm. 8. Seed rind. 9. Pericarp. 10. Seed. 11. Fruit. 12. S.G. Navashin.

Task 4.22.

1. The flowering plant itself. 2. A modified shoot adapted for sexual reproduction. 3. The totality of stamens in a flower. 4. The set of pistils in a flower. 5. Pollen grain. 6. Embryo sac. 7. Fusion of one sperm with the egg, the second with the central cell. 8. Nutrient tissue of the seed. 9. Covers of the ovule. 10. The structure from which the seed subsequently develops.

Task 4.23.

***1 - blastocoel; 2 - blastoderm; 3 - blastopore, primary mouth; 4 - ectoderm; 5 - endoderm; 6 - gastrocoel; 7 - mesoderm; 8 - neural tube; 9 - chord; 10 - transplantation of a section of ectoderm from the dorsal side of one gastrula to the ventral side of the other; 11 - formation of an additional axial complex.

Blastula.

*** Primary body cavity.

Blastopore, primary mouth.

From the ectoderm.

An additional embryo will form.

Task 4.24.

germ layers	Derivatives of the germ layers
ectoderm	The epidermis of the skin, hair, nails, sweat, sebaceous and mammary glands. From the neural plate - the nervous system, components of the organs of vision, hearing, smell, tooth enamel, epithelium of the oral cavity and rectum.
Endoderm	Intestines, liver, pancreas and lungs.
mesoderm	Cartilage and bone skeleton, connective tissue layer of the skin, skeletal muscles, excretory, circulatory and reproductive systems.

Task 4.25.

Test 1: 2. Test 2: 1. Test 3: 1. Test 4: 2. Test 5: 4. Test 6: 3. **Test 7: 1, 2, 5.**Test 8: 6, 7, 8, 10. **Test 9: 3, 4, 8, 9. **Test 10: 4, 5, 6, 8.

Task 4.26.

1. Ontogeny. 2. Embryonic development. 3. Postembryonic development. 4. Blastula formation. 5. Gastrula. 6. Echinoderms and chordates. 7. Neirula. 8. The epidermis of the skin, hair, nails, sweat, sebaceous and mammary glands. From the neural plate - the nervous system, components of the organs of vision, hearing, smell, tooth enamel, epithelium of the oral cavity and rectum. 9. Intestines, liver, pancreas and lungs. 10. With direct - birds and spiders, with indirect - frogs and butterflies.

Task 4.27.

1. Fusion of germ cells. 2. Fertilized egg. 3. Cells resulting from the first divisions of the zygote. 4. An embryo with a primary cavity inside. 5. Cavity inside the blastula, primary cavity. 6. An embryo in which germ layers are formed: ectoderm, endoderm and mesoderm. 7. Third germ layer. 8. A hole formed when the cells of its wall are pushed into the cavity of the blastula. It later becomes the anus. 9. An embryo in which an axial complex of organs has formed. 10. Development with the larval stage.

Task 4.28.

1. Karyotype. 2. In somatic cells of organisms with a diploid set of chromosomes, the chromosome set is diploid, in gametes it is haploid; in somatic cells of an organism with a haploid set of chromosomes, the chromosome set is haploid, gametes are formed mitotically and have a haploid set of chromosomes. 3. G 1 - 2n2c, at the end of the S-period - 2n4c, G 2 - 2n4c. 4. Homologous. 5. The primary constriction is the centromere, the ends of the chromosome are telomeres. 6. Before mitosis 2n4c, after mitosis 2n2c. 7. In prophase - 2n4c, in metaphase - 2n4c, in anaphase -4n4c. 8. Recombination of genetic material and reduction of the chromosome set in germ cells. 9. Reduction and equational. 10. DNA replication ends, conjugation, crossing-over occurs and the same processes occur as in the prophase of mitosis. 11. Before meiosis - 2n4c, after the first division - n2c, after the second - nc. 12. In metaphase 1 and anaphase 1 - 2n4c. 13. Short, no S-period. 14. In metaphase 2 - n2c, in anaphase 2 - 2n2c. 15. Into prophase 1, into anaphase 1, into anaphase 2. 16. Prophase 1, metaphase 1, anaphase 1, telophase 1, interphase 2, prophase 2, metaphase 2. 17. Daughter organisms have the genes of only one, the mother organism. 18. Shizogony. 19. If spores are formed as a result of mitosis, then they have the same chromosome set as the cells of the mother organism; if their formation is preceded by meiosis, the chromosome set is reduced and the genetic material is recombined. 20. In flowering plants, spores are haploid. Some groups of organisms may have a diploid set of chromosomes. 21. Two layers of cells, called the brilliant and radiant membranes. 22. At the third month of embryogenesis. 23. Parthenogenesis. 24. Gametogonia - 2n, gametocytes of the 1st order 2n4c, gametocytes of the 2nd order n2c. 25. Four spermatozoa. 26. One egg and three polar (direction) bodies. 27. Most fish and amphibians. 28. Male gametophyte - pollen grain, female gametophyte - embryo sac. 29. From integuments - seed coat, from the central cell - triploid endosperm. 30. From the walls of the ovary. 31. S.G. Navashin. 32. Embryogenesis and postembryonic development. 33. Cleavage (blastulation), gastrulation and organogenesis. 34. Blastula. 35. Gastrula. 36. From the ectoderm: the epidermis of the skin and its derivatives, the nervous system, the sense organs and the posterior pituitary gland. From the endoderm: the digestive and respiratory systems, the anterior pituitary gland and the thyroid gland. From the mesoderm: skeleton, musculature, genital, excretory and circulatory system. 37. The spine - from the mesoderm, the epidermis of the skin - from the ectoderm, the lungs - from the endoderm. 38. Echinoderms and chordates. 39. Reptiles, birds, mammals. 40. Amphibians, insects, bony fish.

The period of existence of a cell from the moment of its formation by division of the mother cell (including division itself) to its own division or death is called life (cell) cycle.

The duration of the life cycle in different cells of a multicellular organism is different. Thus, the cells of the nervous tissue after the completion of the embryonic period cease to divide and function throughout the life of the organism, and then die. The cells of the embryo at the stage of crushing, having completed one division, immediately proceed to the next, bypassing all other phases.

Mitosis- indirect division of somatic cells, as a result of which doubling first occurs, and then a uniform distribution of hereditary material between daughter cells.

biological significance Mitosis: As a result of mitosis, two cells are formed, each of which contains the same number of chromosomes as there were in the mother. Daughter cells are genetically identical to the parent. As a result of mitosis, the number of cells in the body increases, which is one of the main mechanisms of growth. Many plant and animal species reproduce asexually by mitotic cell division alone, thus mitosis is the basis of reproduction. . Mitosis ensures the regeneration of lost parts and cell replacement, which occurs to one degree or another in all multicellular organisms.

Mitotic cycle-consists of interphase and mitosis. The duration of the mitotic cycle varies greatly in different organisms. Direct cell division usually takes 1-3 hours, that is, the main part of the cell's life is in interphase.

Interphase called the interval between two cell divisions. The duration of interphase, as a rule, is up to 90% of the entire cell cycle. Consists of three periods: presynthetic, or G 1 ; synthetic, or S, postsynthetic, or G 2 .

The initial segment of the interphase - presynthetic period(2n2c, where n is the number of chromosomes, c is the amount of DNA), period of growth beginning immediately after mitosis. synthetic period. The duration of the synthetic period is different: from several minutes in bacteria to 6-12 hours in mammalian cells. During the synthetic period, the most important event of interphase occurs - the duplication of DNA molecules. Each chromosome becomes two-chromatid, and the number of chromosomes does not change (2n4c).

post-synthetic period. Provides preparation of the cell for division and is also characterized by intensive processes of protein synthesis that make up the chromosomes; enzymes and energy substances necessary to ensure the process of cell division are synthesized.

Mitosis. For the convenience of studying the events occurring during division, mitosis is artificially divided into four stages: prophase, metaphase, anaphase, telophase.

Prophase(2n4c). As a result of spiralization, the chromosomes are compacted and shortened. In late prophase, it is clearly seen that each chromosome consists of two chromatids connected by a centromere. Chromosomes begin to move towards the cell equator. The spindle is formed, the nuclear membrane disappears, and the chromosomes are freely located in the cytoplasm. The nucleolus usually disappears a little earlier.

metaphase(2n4c). Chromosomes line up in the plane of the equator, forming the so-called metaphase plate. The centromeres of chromosomes lie strictly in the plane of the equator. The spindle threads are attached to the centromeres of the chromosomes, some threads pass from pole to pole of the cell without attaching to the chromosomes.

Anaphase(4n4c). It begins with the division of the centromeres of all chromosomes, as a result of which the chromatids turn into two completely separate, independent daughter chromosomes. Then the daughter chromosomes begin to diverge towards the poles of the cell.

Telophase(2n2c). Chromosomes are concentrated at the poles of the cell and despiralized. The spindle of division is destroyed. A shell of the nuclei of daughter cells is formed around the chromosomes, then the division of the cytoplasm of the cell (or cytokinesis) occurs.

When animal cells divide, a furrow appears on their surface in the equatorial plane, which, gradually deepening, divides the mother cell into two daughter cells. In plants, division occurs by the formation of a so-called cell plate that separates the cytoplasm. It arises in the equatorial region of the spindle, and then grows in all directions, reaching the cell wall.

Lesson 2. Meiosis

Tasks. To form knowledge about the features of the formation of germ cells with a haploid set of chromosomes, about the uniqueness of gametes and the mechanisms of recombination of genetic material during meiosis, about the similarities and differences between meiosis and mitosis, about the need to protect the natural environment from pollution by mutagens.

Repeat the morphology of chromosomes, the mitotic cycle and the processes occurring in different periods of the mitotic cycle, the significance of mitosis.

Equipment. Demo material: tables by general biology, filmstrip "Cell division", codogram.

During the classes:

Written work with cards for 10 min.

1. Characteristics of the interphase.

2. Characteristics of mitosis.

3. Morphology of chromosomes.

Working with a card at the blackboard: Appendix 2.

Computer testing: appendix 3.

oral repetition.

1. The first division of meiosis.

Meiosis is the main stage in the formation of germ cells. During meiosis, there is not one (as in mitosis), but two successive cell divisions. The first meiotic division is preceded by interphase I - the phase of cell preparation for division, at which time the same processes occur as in the interphase of mitosis.

The first meiotic division is called reduction, since it is during this division that a decrease in the number of chromosomes occurs, two cells are formed with a haploid set of chromosomes, but the chromosomes remain two-chromatid. Immediately after the first division of meiosis, the second division takes place - according to the type of ordinary mitosis. This division is called equational, since during this division, the chromosomes become single chromatid.

The biological significance of meiosis: due to meiosis, a reduction in the number of chromosomes occurs. From one diploid cell, 4 haploid cells are formed. Thanks to meiosis, genetically different gametes are formed, because. in the process of meiosis, the recombination of genetic material occurs three times: due to crossing over; random and independent divergence of homologous chromosomes, and then chromatids. Meiosis maintains the constancy of the diploid set of chromosomes in somatic cells.

I and II divisions of meiosis consist of the same phases as mitosis, but the essence of changes in the hereditary apparatus is different.

Prophase I.(2n4c). The longest and most complex phase of meiosis. Consists of a number of successive stages. Homologous chromosomes begin to be attracted to each other by similar regions and conjugate. conjugation called the process of close convergence of homologous chromosomes. A pair of conjugating chromosomes is called bivalent. Bivalents continue to shorten and thicken. Each bivalent is formed by four chromatids. Therefore it is called tetrad. major event is crossing over- exchange of parts of chromosomes. Crossing over leads to the first recombination of genes during meiosis. At the end of prophase I, the nuclear envelope and nucleolus disappear. Bivalents move to the equatorial plane. Centrioles (if any) move to the poles of the cell, and the spindle is formed.

Metaphase I(2n; 4s). The formation of the fission spindle is completed. Spiralization of chromosomes is maximum. Bivalents are located in the plane of the equator. Moreover, the centromeres of homologous chromosomes are facing different poles of the cell. The location of bivalents in the equatorial plane is equally probable and random, that is, each of the paternal and maternal chromosomes can be turned towards one or the other pole. This creates prerequisites for the second gene recombination during meiosis. The spindle fibers are attached to the centromeres of chromosomes.

Anaphase I(2n; 4s). Whole chromosomes diverge to the poles, not chromatids, as in mitosis. Each pole has half of the chromosome set. Moreover, pairs of chromosomes diverge as they were located in the plane of the equator during metaphase. As a result, a wide variety of combinations of paternal and maternal chromosomes arise, and a second recombination of genetic material occurs.

Telophase I(1n; 2s). In animals and some plants, the chromatids despiralize and a nuclear membrane forms around them. Then the cytoplasm divides (in animals) or a separating cell wall is formed (in plants). In many plants, a cell from anaphase I immediately transitions to prophase II.

2. The second division of meiosis.

Interphase II(1n; 2s). It is characteristic only for animal cells. DNA replication does not occur.

The second stage of meiosis also includes prophase, metaphase, anaphase, and telophase. It proceeds in the same way as normal mitosis.

Prophase II(1n; 2s). Chromosomes spiralize, the nuclear membrane and nucleoli are destroyed, centrioles, if any, move to the poles of the cell, and a division spindle is formed.

Metaphase II(1n; 2s). The metaphase plate and spindle are formed, and the filaments of the spindle are attached to the centromeres.

Anaphase II(2n; 2s). The centromeres of the chromosomes divide, the chromatids become independent chromosomes, and the spindle fibers stretch them to the poles of the cell. The number of chromosomes in a cell becomes diploid, but a haploid set is formed at each pole. Since in metaphase II the chromatids of chromosomes are randomly located in the plane of the equator, the third recombination of the genetic material of the cell occurs in anaphase, since as a result of crossing over the chromatids began to differ from each other and daughter chromatids move to the poles, but different from each other.

Telophase II(1n; 1s). The fission spindle threads disappear, the chromosomes despiralize, the nuclear envelope around them is restored, and the cytoplasm divides. Thus, as a result of two successive divisions of meiosis, a diploid cell gives rise to four daughter cells, genetically various cells with a haploid set of chromosomes.

Appendix 1. Codegram. Appendix 2 Cards at the blackboard.

Appendix 3. Computer testing.

Task 14. "Mitosis".

Test 1. Doubles the amount of DNA in a cell:

1. In the presynthetic period.

2. In the synthetic period.

4. In metaphase.

Test 2 Active cell growth occurs:

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 3. The cell has a set of chromosomes and 2n4c DNA and is preparing to divide:

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

Test 4 Chromosome spiralization begins, the nuclear envelope dissolves:

1. In anaphase.

2. In prophase.

3. In telophase.

4. In metaphase.

Test 5 Chromosomes line up along the equator of the cell.

Lesson time- 90 min.

Location- classroom

Class type- seminar session

Lesson objectives:

Tutorial:

Summarize the knowledge of students on the studied material, skills, abilities; assess the level of knowledge; to control knowledge, skills, abilities; organize knowledge.

Developing:

To teach to analyze, highlight the main thing, develop professional skills

Educational:

Education of perseverance and determination in achieving the goal, confidence in knowledge, develop the ability to think; fostering a culture of communication, curiosity, objectivity.

methodical

Activate cognitive activity students by solving the tasks assigned to them.

Tasks:

1. The development of the student's speech, logical thinking and attention, the ability to analyze, compare, highlight the main thing.

2. education of a value attitude to life, the value of practical knowledge.

3. deepening students' knowledge of this material, enhancing cognitive activity.

Work form: individual, group.

Qualifications

To knowledge:

Students should know the material on the topics: "Properties of living organisms", "Cell", "Cell division", "Mitosis", "Meiosis".

For skills:

Students should be able to freely navigate the material of the topics studied.

Compare knowledge and find solutions.

Draw conclusions, conclusions, justify your point of view.

Interdisciplinary connections:Anatomy, psychology, medicine.

Internal connections: Topics: "Properties of living organisms", "Cell", "Cell division", "Mitosis", "Meiosis", "Fertilization", "Forms of reproduction of organisms"

Equipment: illustrative material, video program, multimedia complex, light microscopes, magnetic board, micropreparations "Mitosis in an onion root", "Ovum division".

Equipment:

multimedia complex
Didactic material: cards

Literature:

Main literature

Internet resources:

1. Russian state library[Electronic resource] / Center inform. RSL technologies; ed. Vlasenko T.V. ; Web-master Kozlova N.V. — Electron. Dan. — M.: Ros. state library, 1997—access mode: http://www.rsl.ru, free. — Zagl. from the screen. - Yaz. Russian, English

2. A selection of Internet materials for biology teachers in various biological disciplines [Electronic resource] / NPB im. K.D. Ushinsky RAO - Access mode: http://www.gnpbu.ru

3. A single collection of digital educational resources [Electronic resource] / 2006-2012 FGAU GNII ITT "Informika"
Mass media registration certificate El No. FS 77 - 47492 dated November 25, 2011 - Access mode: http://school-collection.edu.ru, free. - Zagl. From the screen. - Yaz. Russian

4. Site for teachers of students [Electronic resource] / Publishing House "First of September" - Access mode: http://1september.ru, free. - Zagl. From the screen. - Yaz. Russian

5. Personal website of biology teacher Kapshuchenko A.N. [Electronic resource] free. - Zagl. From the screen. - Yaz. Russian

Rationale for the topic

The topic "Mitosis" is one of the key topics of biology. It links most sections of biology into a single whole. It is the key to the study of such topics as "Fertilization", "Embryonic development", "Ontogeny", "Patterns of inheritance of traits", "Variability" and others. The topic is directly related to the study of a number of medical sciences Key words: obstetrics, gynecology, anatomy, physiology, medical genetics, psychology.

Allows you to consider a number of social aspects, prospects and achievements modern science. Aim students to study subsequent biology topics. Determine interdisciplinary connections.

Lesson plan

№	Lesson stage	Time		Activity
№	Lesson stage	Time		teacher	student
	Organizational		Announcement of the topic, objectives of the lesson	Greets students, organizes attention, communicates the topic and purpose of the lesson.	Greet the teacher
			Assessing the readiness of the audience and students	Checks those present	Participate in roll call
			Description of the order of the seminar.	Explains the procedure for conducting a seminar, the evaluation criteria for a practical lesson. Clarifies the issues that caused difficulties, gives explanations	Listen carefully and ask questions
	Systematization of knowledge		Frontal survey	Asking questions	Answer questions
	Control of knowledge and skills.		Characteristics of the procedure practical work	Explains the order of tasks, controls the implementation, gives explanations, individual consultations	Do the job
	The final stage		Generalization, conclusions	Analysis of the achievement of the goal. Evaluation of students' work.	Listen, analyze, evaluate their work
	The final stage		Answers to students' questions	Answers students' questions, gives necessary explanations	Asking questions, listening to answers
	Total

Attachment 1.

Questions for frontal survey

What are the types of cell division?
How is amitosis different from other types of cell division?
What is mitosis? What is its biological meaning?
What processes take place in the nucleus during interphase?
Why do chromosomes consist of two chromatins at the beginning of mitosis?
What changes occur during the prophase of mitosis in the nucleus?
What part of the chromosome is attached to the spindle thread?
What is characteristic of the metaphase of mitosis?
Why is telophase called "prophase in reverse"?
What chromosomes diverge to the poles of the cell in anaphase?
What are the chromosomes at the beginning of interphase?
How many cells and with what set of chromosomes are formed as a result of mitosis?
What cells are characterized by mitosis?
What chromosomes are called homologous?
What is characteristic of prophase?
How many cells result from mitosis?
What is the difference between mitosis and meiosis?

Appendix 2

Repetition of the material covered. The following terms are written on the board:

Centriole
replication
cell cycle
Chromatin
Chromatids
Chromosomes
Centromere
Interphase

Students are asked to answer next questions and choose the correct answer by writing it in the form of a digital option:

What is the name of the complex consisting of DNA and proteins - histones?
What is the name of the structure formed before nuclear fission?
What is the period before nuclear fission called?
What is the name of the site where the spindle fibers are attached?
What is the name of the structure of the cell center?
What is the process of duplicating a DNA molecule called?
What is the period in the life of a cell from its formation to division into daughter cells called?
What is the name of one of the two nucleoprotein filaments formed when chromosomes are duplicated?

Appendix 3

Determining the time and place of mitosis in the cell cycle.

On the magnetic board there is an image of the cell cycle, the "mitosis" section is highlighted, the average time is determined: interphase lasts 10 - 20 hours, mitosis 1 - 2 hours. It is also possible to determine the genetic material before division. Mitosis is followed by cytokinesis.

Definition of mitosis

“mitosis (from gr. - mitosis - thread) is an indirect division of the cell nucleus and its body, during which each of the two emerging cells receives genetic material identical to the original cell.” Synonyms for nuclear fission is - karyokinesis (translated from gr. karyon - nut, nut kernel, kinesis - movement)

Phases of mitosis: prophase, metaphase, anaphase, telophase, and then cytokinesis follows (work in a notebook)

Appendix 4

Student laboratory work. Task: each group receives an envelope containing information about each phase of mitosis, in addition to illustrated material. Considering micropreparations, find a certain phase according to the description, add a certain text from the fragments, stick it on a sheet of paper.

1 group. Prophase.

Chromatids shorten and thicken. The chromatids are clearly visible. Centromeres are not detected. The centrioles move apart at the poles. A microtubule star begins to form. The nucleoli are reduced. By the end of prophase, the nuclear membrane disintegrates and the spindle is formed.

2 group. Metaphase.

Pairs of chromatids are attached by their centromeres to the filaments of the spindle of division and move up and down the spindle until their centromeres line up along the equator of the cell.

3rd group. Anaphase.

Short stage. Each centromere splits into two, and the spindle filaments pull off the daughter centromeres with the opposite pole. Centromeres pull the chromatids separated from each other, now called chromosomes.

4 group. Telophase.

Chromosomes reach the poles of the cell, despiralize, elongate, indistinguishable spindle threads are destroyed, centrioles replicate. A nuclear membrane forms around the chromosomes. The nucleolus appears.

5 group. Cytokinesis.

Following telophase and leading to the first period of interphase, the organelles are distributed among the daughter cells. As a result, two cells are formed with a set of chromosomes identical to the parent.

Students present their work on the board and show the phase of mitosis on the screen of the multimedia complex.
Interactive part (computer program)
Illustrated material for the video.

Mitosis underlies the growth, regeneration, and vegetative reproduction of all eukaryotic organisms. Further, we will see how this happens at the moment of crushing a fertilized egg - the process that underlies the formation of a multicellular embryo (demonstration of a micropreparation "crushing an egg" on an electron and light microscope).

Demonstration of the video fragment "Mitosis"
Mitosis is a very significant process, a lot of effort and time has been spent by scientists to understand all the features of this process. For example, it was found that mitosis in plant and animal cells proceeds with certain differences, that there are factors that adversely affect its course. In addition, in the literature you can see another form of division - direct or amitosis. Work with additional literature.

Group 1: task "Amitosis"

Select "reference" points from the text, i.e. in 4-5 positions indicate the main signs of amitosis. “Mitosis is the most common, but not the only type of cell division. Almost all eukaryotes have the so-called direct nuclear fission, or amitosis. During amitosis, there is no condensation of chromosomes and no spindle is formed, and the nucleus is divided by constriction or fragmentation, remaining in the interphase state. Cytokinesis always follows nuclear division, resulting in the formation of a multinucleated cell. Amitotic division is typical for cells that complete development: dying epithelial, follicular cells of the ovaries ... Amitosis also occurs in pathological processes: inflammation, malignant neoplasm ... after it, cells are not capable of mitotic division.

Group 2: task "violation of mitosis"

Make logical pairs: type of impact - consequences.

“The correct course of mitosis can be disturbed by various external factors: high doses of radiation, certain chemicals. For example, under the influence of X-rays, the DNA of the chromosome can break, and the chromosomes also break. Such chromosomes are not able to move, for example, in anaphase. Some chemicals that are not characteristic of living organisms (alcohols, phenols) disrupt the coordination of mitotic processes. Some chromosomes move faster, others slower. Some of them may not be included in child kernels at all. There are substances that prevent the formation of fission spindle filaments. They are called cytostatics, for example, colchicine and colcemide. By acting on the cell, division can be stopped at the prometaphase stage. As a result of such an impact, a double set of chromosomes appears in the nucleus.

Group 3: task:

Restore the chronological sequence of studying the cell, including the processes of mitosis. Answer in the form of a table:

“The study of the cell began with the invention of the microscope. The first to appreciate the great importance of this device was the English physicist and botanist Robert Hooke. He introduced the term "cell" (1665). Ideas about the self-reproduction of cells developed among biologists by the middle of the 19th century. In 1838-39, the botanist Schleiden and the zoologist Schwann combined the ideas of various scientists and formed cell theory, which postulated "the basic unit of structure and function of living organisms is the cell" Somewhat earlier, the nucleus was discovered by Robert Brown, he described this structure as a characteristic spherical body found in plant cells. In 1868, Haeckel established that the nucleus carries out the storage and transmission of hereditary traits. Ten years earlier, Rudolf Virchow had expanded cell theory by proclaiming "every cell is from a cell." In 1879, Boveri and Fleming described events occurring in a cell that resulted in the formation of two identical cells.

4 group. Task: "The difference between mitosis in plants and animals."

After analyzing the text, find the differences in the course of mitosis in plants and animals. Fill the table.

The most important event that occurs during mitosis is the even distribution of duplicated chromosomes between two daughter cells. Mitosis in plant and animal cells proceeds almost in the same way, but there are still differences. So, for example, in plant cells there are no centrioles. At the end of the telophase in plant cells, a phragmoplast is formed from the fission spindle filaments in the equatorial part, and ribosomes, mitochondria, and EPS move to the same area. All this leads to the formation of a cell plate, which subsequently divides the cell in two. This process is not observed in animals. There are also differences in cytokinesis, for example, constriction is formed only in animals. Mitoses in animals occur in various tissues and parts of the body, which cannot be said about plants. There, mitosis occurs in strictly defined places where the educational tissue is located, that is, in the meristems. For example, at the tips of the root (growth zone), in the kidney (growth cone), cambium.

5 group. Task: create a symbolic sign that would fit the topic of our lesson. Work in a notebook and on a sheet of paper using colored pencils.

Student performances.
Conclusions.

Today the lesson was devoted to the most important process - mitosis. We devoted enough time to the process itself, its features and problems. Most importantly, this process ensures the genetic stability of the species, as well as the processes of regeneration, growth, and asexual (vegetative) reproduction. The process is complex, multistage and very sensitive to environmental factors.

Annex 5

Brainstorming (consolidating the studied material)

№	The cell and its phases	total weight all DNA molecules	Number of chromosomes
	In one non-dividing somatic cell	*610-9mg**	46
	In one somatic cell at the end of interphase, before prophase
	In the maternal somatic cell in its prophase and metaphase of mitosis
	Maternal somatic cell in anaphase
	In one daughter somatic cell at the end of the telophase of mitosis
	In two daughter somatic cells (sum) at the end of the telophase of mitosis

Annex 5

Testing: "Mitosis"

1. During what period of the mitotic cycle does the amount of DNA double?

2. In the synthetic period.

4. In metaphase.

2. During what period does active cell growth occur?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

3. At what period of the life cycle does a cell have a set of chromosomes and 2n4c DNA and is preparing for division?

1. In the presynthetic period.

2. In the synthetic period.

3. In the post-synthetic period.

4. In metaphase.

4. During what period of mitosis does the spiralization of chromosomes begin, does the nuclear membrane dissolve?

1. In anaphase.

2. In prophase.

3. In telophase.

4. In metaphase.

5. During what period of mitosis do chromosomes line up along the equator of the cell?

1. In prophase.

2. In metaphase.

3. In anaphase.

4. In telophase.

6. During what period of mitosis do chromatids move away from each other and become independent chromosomes?

1. In prophase.

2. In metaphase.

3. In anaphase.

4. In telophase.

*7. In what periods of mitosis is the number of chromosomes and DNA equal to 2n4c?

1. In prophase.

2. In metaphase.

3. In anaphase.

4. In telophase.

8. In what period of mitosis is the number of chromosomes and DNA equal to 4n4c?

1. In prophase.

2. In metaphase.

3. In anaphase.

4. In telophase.

9. What is the name of the inactive part of DNA in a cell?

1. Chromatin.

2. Euchromatin.

3. Heterochromatin.

4. All DNA in the cell is active.

*ten. At what periods of the cell cycle is the number of chromosomes and DNA in a cell equal to 2n4c?

1. In the presynthetic period.

2. At the end of the synthetic period.

3. In the post-synthetic period.

4. In prophase.

5. In metaphase.

6. In anaphase.

7. In telophase.

There are several correct answers to the question.

Answers on the topic "Mitosis":

Test 1. 2.

Test 2. 1.

Test 3. 3.

Test 4. 2.

Test 5. 2.

Test 6. 3.

*Test 7. 1, 2.

Test 8.3.

Test 9.3.

*Test 10. 2, 3, 4, 5.