4 phases of mitosis. Stages (phases) of mitosis. What biological role does mitosis play?

Mitosis (indirect division) is the division of somatic cells (cells of the body). The biological significance of mitosis is the reproduction of somatic cells, the production of copy cells (with the same set of chromosomes, with exactly the same hereditary information). All somatic cells in the body are derived from a single parent cell (zygote) through mitosis.

1) Prophase

chromatin spirals (twists, condenses) into chromosomes
nucleoli disappear
the nuclear envelope disintegrates
Centrioles diverge to the cell poles, a spindle is formed

2) Metaphase- chromosomes line up along the equator of the cell, a metaphase plate is formed

3) Anaphase- daughter chromosomes separate from each other (chromatids become chromosomes) and move towards the poles

4) Telophase

chromosomes despiral (unwind, decondense) to the state of chromatin
the nucleus and nucleoli appear
spindle filaments are destroyed
cytokinesis occurs - the division of the cytoplasm of the mother cell into two daughter cells

The duration of mitosis is 1-2 hours.

Cell cycle

This is the period of a cell’s life from the moment of its formation through the division of the mother cell until its own division or death.

The cell cycle consists of two periods:

interphase(the state when the cell does NOT divide);
division (mitosis or).

Interphase consists of several phases:

presynthetic: the cell grows, active synthesis of RNA and proteins occurs in it, and the number of organelles increases; in addition, preparation for DNA doubling occurs (accumulation of nucleotides)
synthetic: doubling (replication, reduplication) of DNA occurs
postsynthetic: the cell prepares for division, synthesizes substances necessary for division, for example, spindle proteins.

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PART 2 ASSIGNMENTS:

Tests and assignments

Choose one, the most correct option. The process of reproduction of cells of organisms of different kingdoms of living nature is called
1) meiosis
2) mitosis
3) fertilization
4) crushing

Answer

1. All of the following features, except two, can be used to describe the processes of interphase of the cell cycle. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.
1) cell growth
2) divergence of homologous chromosomes
3) arrangement of chromosomes along the equator of the cell
4) DNA replication
5) synthesis of organic substances

Answer

2. All of the following features, except two, can be used to describe the processes occurring in interphase. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated in the table.
1) DNA replication
2) formation of the nuclear membrane
3) chromosome spiralization
4) ATP synthesis
5) synthesis of all types of RNA

Answer

3. The processes listed below, except two, are used to characterize interphase of the cell cycle. Identify two processes that “fall out” from the general list and write down the numbers under which they are indicated.
1) formation of the spindle
2) ATP synthesis
3) replication
4) cell growth
5) crossing over

Answer

Choose one, the most correct option. At what stage of life do chromosomes spiral into cells?
1) interphase
2) prophase
3) anaphase
4) metaphase

Answer

Choose three options. Which cell structures undergo the greatest changes during mitosis?
1) core
2) cytoplasm
3) ribosomes
4) lysosomes
5) cell center
6) chromosomes

Answer

1. Establish the sequence of processes occurring in a cell with chromosomes in interphase and subsequent mitosis
1) arrangement of chromosomes in the equatorial plane
2) DNA replication and formation of two-chromatid chromosomes
3) chromosome spiralization
4) divergence of sister chromosomes to the cell poles

Answer

2. Establish the sequence of processes occurring during interphase and mitosis. Write down the corresponding sequence of numbers.
1) spiralization of chromosomes, disappearance of the nuclear membrane
2) divergence of sister chromosomes to the cell poles
3) formation of two daughter cells
4) doubling of DNA molecules
5) placement of chromosomes in the plane of the cell equator

Answer

3. Establish the sequence of processes occurring in interphase and mitosis. Write down the corresponding sequence of numbers.
1) dissolution of the nuclear membrane
2) DNA replication
3) destruction of the fission spindle
4) divergence of single-chromatid chromosomes to the cell poles
5) formation of a metaphase plate

Answer

4. Establish the correct sequence of processes occurring during mitosis. Write down the numbers under which they are indicated.
1) decay of the nuclear shell
2) thickening and shortening of chromosomes
3) alignment of chromosomes in the central part of the cell
4) the beginning of the movement of chromosomes towards the center
5) divergence of chromatids to the cell poles
6) formation of new nuclear membranes

Answer

5. Establish the sequence of processes occurring during mitosis. Write down the corresponding sequence of numbers.
1) chromosome spiralization
2) chromatid divergence
3) formation of a fission spindle
4) despiralization of chromosomes
5) division of the cytoplasm
6) location of chromosomes at the equator of the cell

Answer

6. Establish the sequence of processes occurring during mitosis. Write down the corresponding sequence of numbers.
1) spindle threads are attached to each chromosome
2) the nuclear envelope is formed
3) doubling of centrioles occurs
4) protein synthesis, increase in the number of mitochondria
5) the centrioles of the cell center diverge to the cell poles
6) chromatids become independent chromosomes

Answer

FORMING 7:

4) disappearance of spindle threads

Choose one, the most correct option. When a cell divides, a spindle is formed in
1) prophase
2) telophase
3) metaphase
4) anaphase

Answer

Choose one, the most correct option. Mitosis does NOT occur in prophase
1) dissolution of the nuclear membrane
2) formation of the spindle
3) chromosome doubling
4) dissolution of nucleoli

Answer

Choose one, the most correct option. At what stage of life do chromatid cells become chromosomes?
1) interphase
2) prophase
3) metaphase
4) anaphase

Answer

Choose one, the most correct option. Unspiralization of chromosomes during cell division occurs in
1) prophase
2) metaphase
3) anaphase
4) telophase

Answer

Choose one, the most correct option. In what phase of mitosis are pairs of chromatids attached by their centromeres to the filaments of the spindle?
1) anaphase
2) telophase
3) prophase
4) metaphase

Answer

Establish a correspondence between the processes and phases of mitosis: 1) anaphase, 2) telophase. Write numbers 1 and 2 in the correct order.
A) the nuclear envelope is formed
B) sister chromosomes diverge to the poles of the cell
C) the spindle finally disappears
D) chromosomes despiral
D) chromosome centromeres separate

Answer

Establish a correspondence between the characteristics and phases of mitosis: 1) metaphase, 2) telophase. Write numbers 1 and 2 in the order corresponding to the letters.
A) Chromosomes consist of two chromatids.
B) Chromosomes despiral.
C) The spindle strands are attached to the centromere of the chromosomes.
D) The nuclear envelope is formed.
D) Chromosomes line up in the equatorial plane of the cell.
E) The division spindle disappears.

Answer

Establish a correspondence between the characteristics and phases of cell division: 1) anaphase, 2) metaphase, 3) telophase. Write numbers 1-3 in the order corresponding to the letters.
A) despiralization of chromosomes
B) number of chromosomes and DNA 4n4c
B) arrangement of chromosomes along the equator of the cell
D) divergence of chromosomes to the poles of the cell
E) connection of centromeres with spindle filaments
E) formation of the nuclear membrane

Answer

All but two of the characteristics listed below are used to describe the phase of mitosis shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) the nucleolus disappears
2) a fission spindle is formed
3) DNA molecules double
4) chromosomes are actively involved in protein biosynthesis
5) chromosomes spiral

Answer

Choose one, the most correct option. What is accompanied by the spiralization of chromosomes at the beginning of mitosis?
1) acquisition of a dichromatide structure
2) active participation of chromosomes in protein biosynthesis
3) doubling the DNA molecule
4) increased transcription

Answer

Establish a correspondence between the processes and periods of interphase: 1) postsynthetic, 2) presynthetic, 3) synthetic. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) cell growth
B) ATP synthesis for the fission process
B) ATP synthesis for the replication of DNA molecules
D) synthesis of proteins to build microtubules
D) DNA replication

Answer

1. All of the following features, except two, can be used to describe the process of mitosis. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) underlies asexual reproduction
2) indirect division
3) provides regeneration
4) reduction division
5) genetic diversity increases

Answer

2. All of the above characteristics, except two, can be used to describe the processes of mitosis. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) formation of bivalents
2) conjugation and crossing over
3) constancy of the number of chromosomes in cells
4) formation of two cells
5) preservation of chromosome structure

Answer

All of the signs listed below, except two, are used to describe the process shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) daughter cells have the same set of chromosomes as parent cells
2) uneven distribution of genetic material between daughter cells
3) provides growth
4) formation of two daughter cells
5) direct division

Answer

All but two of the processes listed below occur during indirect cell division. Identify two processes that “fall out” from the general list and write down the numbers under which they are indicated.
1) two diploid cells are formed
2) four haploid cells are formed
3) somatic cell division occurs
4) conjugation and crossing over of chromosomes occurs
5) cell division is preceded by one interphase

Answer

1. Establish a correspondence between the stages of the cell life cycle and processes. Occurring during them: 1) interphase, 2) mitosis. Write numbers 1 and 2 in the order corresponding to the letters.
A) the spindle is formed
B) the cell grows, active synthesis of RNA and proteins occurs in it
B) cytokinesis occurs
D) the number of DNA molecules doubles
D) chromosome spiralization occurs

Answer

2. Establish a correspondence between the processes and stages of the cell life cycle: 1) interphase, 2) mitosis. Write numbers 1 and 2 in the order corresponding to the letters.
A) chromosome spiralization
B) intensive metabolism
B) doubling of centrioles
D) divergence of sister chromatids to the cell poles
D) DNA reduplication
E) increase in the number of cell organelles

Answer

What processes occur in a cell during interphase?
1) protein synthesis in the cytoplasm
2) chromosome spiralization
3) synthesis of mRNA in the nucleus
4) reduplication of DNA molecules
5) dissolution of the nuclear membrane
6) divergence of the centrioles of the cell center to the cell poles

Answer

Determine the phase and type of division shown in the figure. Write two numbers in the order specified in the task, without separators (spaces, commas, etc.).
1) anaphase
2) metaphase
3) prophase
4) telophase
5) mitosis
6) meiosis I
7) meiosis II

Answer

All but two of the characteristics listed below are used to describe the stage of the cell life cycle shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) the spindle disappears
2) chromosomes form an equatorial plate
3) a nuclear membrane is formed around the chromosomes at each pole
4) separation of the cytoplasm occurs
5) chromosomes spiral and become clearly visible

Answer

Establish a correspondence between the processes and stages of cell division. Write numbers 1 and 2 in the order corresponding to the letters.
A) destruction of the nuclear membrane
B) chromosome spiralization
B) divergence of chromatids to the poles of the cell
D) formation of single chromatid chromosomes
D) divergence of centrioles to the cell poles

Answer

Look at the drawing. Indicate (A) the type of division, (B) the phase of division, (C) the amount of genetic material in the cell. For each letter, select the corresponding term from the list provided.
1) mitosis
2) meiosis II
3) metaphase
4) anaphase
5) telophase
6) 2n4c
7) 4n4c
8) n2c

Answer

All but two of the features listed below are used to describe the cellular structure shown in the figure. Identify two characteristics that “drop out” from the general list and write down the numbers under which they are indicated.
1) type of cell division - mitosis
2) phase of cell division - anaphase
3) chromosomes, consisting of two chromatids, are attached by their centromeres to the filaments of the spindle
4) chromosomes are located in the equatorial plane
5) crossing over occurs

Answer

In nature, there is a method of dividing eukaryotic cells, in which the process of doubling first occurs, and then the genetic material is evenly distributed between the resulting daughter cells. This division process is called mitosis in biology. In this article you will learn more about the main stages of this division process, and you will be able to see it in diagrams.

Phases of mitosis

The process of division of eukaryotes occurs in four stages:

Prophase;
Metaphase;
Anaphase;
Telophase.

Some scientists initially consider more phases. For example, prophase is preceded by preprophase (the so-called preparation for division), and before metaphase, prometaphase is distinguished. However, in most educational publications, all these additions are combined into a single prophase of mitosis.

Rice. 1. Stages of mitosis

The entire process of division occurs continuously, so each phase of mitosis is smoothly replaced by the next phase.

Let's look at each of them separately:

Prophase ;

At this stage, centrioles are clearly visible, which play an important role during the division of an animal cell.

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There are no centrioles in the nucleus of a plant cell, so mitosis diagrams mainly show the division of an animal cell. And all because the presence of centrioles makes the division process more visual.

Rice. 2. Scheme of mitosis

During prophase, the centrioles divide and move to the poles. Microtubules extend from them, which are the filaments of the spindle. It is this that regulates the divergence of chromosomes to different poles of a cell that is dividing. The spindle threads have different purposes: some are attached to the centromeres of chromosomes, others stretch from pole to pole.

At the end of prophase, the nuclear envelope dissolves, the nucleolus gradually disappears, and the chromosomes spiral, causing them to become shorter and thicker. At this stage they can be clearly seen under a light microscope.

Metaphase ;

At this stage, the spiral-shaped chromosomes are more clearly visible as they move towards the equator of the spindle. The chromatids are also clearly visible; each chromosome has two of them. During the metaphase of mitosis, you can see in a microscope that the chromatids have a constriction - a centromere. It is with its help that chromosomes are attached to the spindle. Once the centromere divides, each chromatid becomes an independent daughter chromosome.

Anaphase ;

It is the shortest phase, during which each already independent chromatid diverges to different poles.

Telophase ;

Now the chromosomes despiral again and take on their original appearance. A nuclear envelope with a nucleolus inside is formed around them. Ribosomes are formed in it. The spindle disappears, chromosomes are no longer visible in a light microscope. There is a uniform distribution of the cytoplasm and its organelles between the two daughter cells.

Result of mitosis

The entire division process takes up to two hours on average. However, it directly depends on external factors: temperature, availability of light and other indicators.

As a result, we get two cells from one cell, which have the same genetic information. In this way, a constant amount of DNA is maintained.

Mitosis provides:

body growth;
transmission of hereditary information;
the process of asexual reproduction is possible in some representatives of living nature;

An example of asexual reproduction is vegetative propagation of plants, hydra budding, etc.

Rice. 3. Methods of vegetative propagation of plants

restoration of tissue cells.

What have we learned?

The process of cell division that preserves genetic information is called mitosis. It occurs in four phases: prophase, metaphase, anaphase, telophase. Each of them has its own characteristics and meaning. As a result of division, two daughter cells with the same chromosome set are formed from one mother cell. Thanks to mitosis, the growth and development of the body, the restoration of tissue cells, asexual reproduction, and most importantly, the transmission of genetic code from generation to generation are possible.

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Mitosis- this is cell division in which daughter cells are genetically identical to the mother and to each other. That is, during mitosis, chromosomes are doubled and distributed between daughter cells so that each receives one chromatid of each chromosome.

There are several stages (phases) in mitosis. However, mitosis itself is preceded by a long interphase. Mitosis and interphase together constitute the cell cycle. During interphase, the cell grows, organelles are formed in it, and synthesis processes are actively underway. During the synthetic period of interphase, DNA is reduplicated, i.e., doubled.

After chromatid duplication, they remain connected in the region centromeres, i.e. the chromosome consists of two chromatids.

Mitosis itself usually has four main stages (sometimes more).

The first stage of mitosis is prophase. During this phase, chromosomes spiral and acquire a compact, twisted shape. Because of this, RNA synthesis processes become impossible. The nucleoli disappear, which means that ribosomes are also not formed, i.e., synthetic processes in the cell are suspended. The centrioles diverge to the poles (to different ends) of the cell, and a division spindle begins to form. At the end of prophase, the nuclear envelope disintegrates.

Prometaphase- This is a stage that is not always isolated separately. The processes occurring in it can be attributed to late prophase or early metaphase. In prometaphase, chromosomes find themselves in the cytoplasm and move randomly around the cell until they connect to the spindle thread in the centromere region.

The filament is a microtubule built from the protein tubulin. It grows by attaching new tubulin subunits. In this case, the chromosome moves away from the pole. From the side of the other pole, a spindle thread also attaches to it and also pushes it away from the pole.

Second stage of mitosis - metaphase. All chromosomes are located nearby in the equatorial region of the cell. Two filaments of the spindle are attached to their centromeres. In mitosis, metaphase is the longest stage.

The third stage of mitosis is anaphase. In this phase, the chromatids of each chromosome are separated from each other and, due to the filaments of the spindles pulling them, they move to different poles. Microtubules no longer grow, but disassemble. Anaphase is a fairly fast phase of mitosis. When chromosomes diverge, cell organelles in approximately equal quantities also diverge closer to the poles.

The fourth stage of mitosis is telophase- in many ways the opposite of prophase. Chromatids gather at the cell poles and unwind, i.e., despiral. Nuclear membranes form around them. Nucleoli are formed and RNA synthesis begins. The fission spindle begins to collapse. Next, the cytoplasm divides - cytokinesis. In animal cells, this occurs due to the invagination of the membrane and the formation of a constriction. In plant cells, the membrane begins to form internally in the equatorial plane and goes to the periphery.

Mitosis. Table

Phase	Processes
Prophase	Spiralization of chromosomes. Disappearance of nucleoli. Disintegration of the nuclear shell. Beginning of spindle formation.
Prometaphase	Attachment of chromosomes to spindle threads and their movement to the equatorial plane of the cell.
Metaphase	Each chromosome is stabilized in the equatorial plane by two strands coming from different poles.
Anaphase	Broken chromosome centromeres. Each chromatid becomes an independent chromosome. Sister chromatids move to different poles of the cell.
Telophase	Despiralization of chromosomes and resumption of synthetic processes in the cell. Formation of nucleoli and nuclear membrane. Destruction of the fission spindle. Centriole duplication. Cytokinesis is the division of the cell body in two.

Cell reproduction is one of the most important biological processes and is a necessary condition for the existence of all living things. Reproduction occurs by dividing the original cell.

Cell is the smallest morphological structural unit of any living organism, capable of self-production and self-regulation. The time of its existence from division to death or subsequent reproduction is called the cell cycle.

Tissues and organs consist of various cells that have their own period of existence. Each of them grows and develops to ensure the vital functions of the body. The duration of the mitotic period is different: blood and skin cells enter the process of division every 24 hours, and neurons are capable of reproduction only in newborns, and then completely lose their ability to reproduce.

There are 2 types of division - direct and indirect. Somatic cells reproduce indirectly; gametes or germ cells undergo meiosis (direct division).

Mitosis - indirect division

Mitotic cycle

The mitotic cycle includes 2 successive stages: interphase and mitotic division.

Interphase(resting stage) - preparation of the cell for further division, where the original material is duplicated, followed by its uniform distribution between the newly formed cells. It includes 3 periods:

- Presynthetic(G-1) G – from the English gar, that is, the gap, preparation is underway for subsequent DNA synthesis, the production of enzymes. Experimentally, inhibition of the first period was carried out, as a result of which the cell did not enter the next phase.
- Synthetic(S) is the basis of the cell cycle. Replication of chromosomes and centrioles of the cell center occurs. Only after this can the cell proceed to mitosis.
- Postsynthetic(G-2) or premitotic period - accumulation of mRNA occurs, which is necessary for the onset of the mitotic stage itself. In the G-2 period, proteins (tubulins) are synthesized - the main component of the mitotic spindle.

After the end of the premitotic period begins mitotic division. The process includes 4 phases:

Prophase– during this period, the nucleolus is destroyed, the nuclear membrane (nucleolem) dissolves, the centrioles are located at opposite poles, forming a division apparatus. Has two subphases:
- early- thread-like bodies (chromosomes) are visible, they are not yet clearly separated from each other;
- late- individual parts of chromosomes can be traced.
Metaphase– begins from the moment of destruction of the nucleolem, when the chromosomes lie chaotically in the cytoplasm and just begin to move towards the equatorial plane. All pairs of chromatids are connected to each other at the centromere.
Anaphase- at one moment all the chromosomes separate and move to opposite points of the cell. This is a short and very important phase because it is during this phase that the precise division of genetic material occurs.
Telophase- the chromosomes stop, the nuclear membrane and nucleolus are formed again. A constriction forms in the middle; it divides the body of the mother cell into two daughter cells, completing the mitotic process. In newly formed cells, the G-2 period begins again.

Meiosis - direct division

There is a special process of reproduction that occurs only in sex cells (gametes) - this is meiosis (direct division). A distinctive feature for it is the absence of interphase. Meiosis from one original cell produces four, with a haploid set of chromosomes. The entire process of direct division includes two successive stages, which consist of prophase, metaphase, anaphase and telophase.

Before the onset of prophase, the germ cells double their initial material, thus becoming tetraploid.

Prophase 1:

Leptotene- chromosomes are visible in the form of thin threads, they shorten.
Zygotene- the stage of conjugation of homologous chromosomes, as a result, bivalents are formed. Conjugation is an important moment of meiosis; chromosomes come as close as possible to each other in order to carry out crossing over.
Pachytena- chromosomes thicken, they become increasingly shortened, crossing over occurs (exchange of genetic information between homologous chromosomes, this is the basis of evolution and hereditary variability).
Diplotena– stage of doubled strands, the chromosomes of each bivalent diverge, maintaining connection only in the region of the cross (chiasma).
Diakinesis— The DNA begins to condense, the chromosomes become very short and separate.

Prophase ends with the destruction of the nucleolem and the formation of the spindle.

Metaphase 1: bivalents are located in the middle of the cell.

Anaphase 1: duplicated chromosomes move to opposite poles.

Telophase 1: the division process is completed, the cells receive 23 bivalents.

Without subsequent doubling of material, the cell enters second phase division.

Prophase 2: all the processes that were in prophase 1 are repeated again, namely the condensation of chromosomes, which are chaotically located between the organelles.

Metaphase 2: two chromatids connected at the crossover (univalents) are located in the equatorial plane, creating a plate called metaphase.

Anaphase 2:- the univalent is divided into separate chromatids or monads, and they are directed to different poles of the cell.

Telophase 2: The division process is completed, the nuclear envelope is formed, and each cell receives 23 chromatids.

Meiosis is an important mechanism in the life of all organisms. As a result of this division, we get 4 haploid cells that have half the required set of chromatids. During fertilization, two gametes form a full-fledged diploid cell, maintaining its inherent karyotype.

It is difficult to imagine our existence without meiotic division, otherwise all organisms would receive double sets of chromosomes with each subsequent generation.

What are mitosis and meiosis and what phases do they have? cells with some differences. During meiosis, four daughter nuclei are formed from the mother nucleus, in which the number of chromosomes is reduced by half. Mitosis also occurs, but in this type only two daughter cells are formed with the same chromosomes as the parents.

So is meiosis? These are biological division procedures that produce cells with specific chromosomes. Reproduction by mitosis occurs in multicellular, complex living organisms.

Stages

Mitosis occurs in two stages:

Doubling information at the gene level. Here, mother cells distribute genetic information among themselves. At this stage, chromosomes change.
Mitotic stage. It consists of time periods.

Cell formation occurs in several stages.

Phases

Mitosis is divided into several phases:

telophase;
anaphase;
metaphase;
prophase.

These phases occur in a certain sequence and have their own characteristics.

In any complex multicellular organism, mitosis most often involves cell division according to an undifferentiated type. During mitosis, the mother cell divides into daughter cells, usually two. One of them becomes a stem and continues division, and the second stops dividing.

Interphase

Interphase is the cell's preparation for division. Typically this stage lasts up to twenty hours. At this time, many different processes take place, during which cells prepare for mitosis.

During this period, protein division occurs and the number of organelles in the DNA structure increases. By the end of division, the genetic molecules double, but the number of chromosomes does not change. Identical DNAs are spliced and are two chromatids in one molecule. The resulting chromatids are identical and sister.

After the completion of interphase, mitosis proper begins. It consists of prophase, metaphase, anaphase and telophase.

Prophase

The first phase of mitosis is prophase. It lasts about an hour. It is conventionally divided into several stages. At the initial stage in the prophase of mitosis, the nucleolus enlarges, as a result of which molecules are formed. By the end of the phase, each chromosome already consists of two chromatids. The nucleoli and nuclear membranes dissolve, all the elements in the cell are in disarray. Further, in the prophase of mitosis, achromatin division is formed, some of the threads pass through the entire cell, and some are connected to the central elements. During this process, the content of the genetic code remains unchanged.

The number of chromosomes does not change in prophase of mitosis. What else happens? In the prophase of mitosis, the nuclear membrane disintegrates, as a result of which spiral chromosomes end up in the cytoplasm. Particles of the disintegrated nuclear membrane form small membrane vesicles.

In the prophase of mitosis, the following happens: the animal cell becomes round, but in plants it does not change shape.

Metaphase

After prophase comes metaphase. In this phase, chromosome spiralization reaches its peak. The shortened chromosomes begin to move towards the center of the cell. During movement, they are located equally in both parts. Here the metaphase plate is formed. When examining a cell, chromosomes are clearly visible. It is during metaphase that they are easy to count.

After the formation of the metaphase plate, the set of chromosomes inherent in this cell type is analyzed. This occurs by blocking chromosome segregation using alkaloids.

Each organism has its own set of chromosomes. For example, corn has 20, and garden strawberries have 56. The human body has fewer chromosomes than berries, only 46.

Anaphase

All processes occurring in prophase of mitosis end and anaphase begins. During this process, all chromosomal connections are broken and begin to move in opposite directions from each other. In anaphase, related chromosomes become independent. They end up in different cells.

The phase ends with the divergence of chromatids to the poles of the cell. Also here the distribution of hereditary information between daughter and mother cells occurs.

Telophase

Chromosomes are located at the poles. Under a microscope, they become difficult to see, as a nuclear shell forms around them. The fission spindle is completely destroyed.

In plants, the membrane forms in the center of the cell, gradually spreading to the poles. It divides the mother cell into two parts. Once the membrane has fully grown, a cellulose wall appears.

Features of mitosis

Cell division can be inhibited due to high temperatures, exposure to poisons, and radiation. When studying cell mitosis in various multicellular organisms, poisons can be used that inhibit mitosis at the metaphase stage. This allows you to study chromosomes in detail and carry out karyotoping.