In the metaphase chromosomes are built on the equator of the cell, forming. Equational division of phase characteristics, chromosome location
Mitosis - The method of indirect division of somatic cells.
Prophase. Chromatin condenses, nucleolo disappears, the centrioles will disappear to the poles of the cell, and the achromatine spindle (spindle divisions) from microtubule begins to form. At the end of the opposite, the nuclear shell disintegrates on separate bubbles.
Metafase. Chromosomes are built up to the equator.
Anaphase. DNA replication in centromers and discrepancy chromatide to cell poles.
Bulfase. Daughter chromosomes are collected on the poles and despirate. Nuclear shells are formed, nuclei have nuclei in the nuclei. After dividing the nucleus, cytoplasm is divided - cytokinesis, during which there is a more or less uniform distribution of all organides of the maternal cell.
Thus, as a result of mitosis, two subsidiaries are formed from one maternal cell, each of which is a genetic copy of the maternal (2N2C). In patients, damaged, aging cells and specialized tissues of the body, a somewhat different division of the division can occur. Amitosis They refer direct division of eukaryotic cells, at which there is no formation of genetically equivalent cells, since the cellular components are dissolved unevenly.
Meiosis - The process that occurs during the formation of weights, genital cells (sperm and egg). As a result, it turns out like nuclei, the merger of which in fertilization (the education of the zygota) leads to the restoration of the diploid number chromosomes. Provides preservation in a number of generations of a constant amount of chromosomes.
Meiosis consists of two consecutive cell divisions (MEIOS 1 and MEIZ 2), each of which is preceded by interfac.
Interfaz 1. It is characterized by the active synthesis of DNA and proteins. Preparation for division.
Meiosis 1.. Unlike mitosis in pROFAZ 1. Maizia occurs conjugation and cross hinge.
Conjugation - This is the process of fusion of homologous (pair) chromosomes along the entire length (the pairs are preserved to the end of metafase 1).
Cross Hopeer - Exchange of homologous sections of homologous chromosomes. As a result of the chromosome crosslinker, obtained by the body from both parents, acquire new combinations of genes, which causes the emergence of genetically diverse offspring.
Completion of Profase 1, as well as the subsequent phases of the first meiotic division (metaphase 1, anatherapy 1, BELFAZ 1) flow around the clusters of chromosomes in the cell poles is similar to the mitosis phases.
Meiosis 2.. The second division of meyosis should be directly behind the EPRA, without expressed interphase, since there is no S-period and does not replicauia DNA. In PROFARE 2, the same processes flow as in Proofase 1, with the exception of conjugation and crosslinker.
IN metafhase 2. Chromosome are located along the cell equator.
IN anafase 2. Chromosomes are split in centroma and chromatids stretch to the poles.
IN bulfase 2. Around the clusters of subsidiaries of chromosomes, nuclear shells and nuclei are formed.
After cytokinesis 2, the genetic formula of all four daughter cells is 1N1C, but they all have a different set of genes, which is the result of a crosslinker and a random combination of chromosome of maternal and paternal organisms in subsidiaries.
Comparison of mitosis and meiosis
"Biology of the structure of the cell" - diffusion. Find out the transport mechanisms of substances through the cell membrane. The topic of the educational project: the structural organization of the cell. Problem questions: Annotation of the project. Features of plant, animal, mushroom cells. Teach to use different sources of information. Integration of the project with the educational topic "The foundations of molecular-kinetic theory.
"The structure of prokaryotic cell" - make a cluster. Sponework. Breathing bacteria. What is the value of bacteria. Features of bacteria. Comparison of pricing cells and eukaryotes. Check and actualization of knowledge. Water. Consolidation of knowledge. Consider carefully pictures. Anthony van Levenguk. Reproduction. When prokaryotic organisms arose.
"Cytoplasm" - supports the turgor (volume) of cells, maintain temperature. EPS functions. Glycolic, synthesis of fatty acids, nucleotides and other substances flows in cytosol. Endoplasmic reticulum. The chemical composition of the cytoplasm is diverse. Cytoplasm. Galioplasma / cytosol. The structure of the animal cell. Alkaline reaction.
"The cell and its structure" - the phases and periods of muscle contraction, b - muscle contraction modes arising from different frequency of muscle stimulation. Movement diagram in muscle miofibrill. The change in the length of the muscle is shown in blue, the potential of the action in the muscle is red, muscle excitability - purple. Transmission of excitation in electrical synapse.
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Cells of multicellular organisms usually have a double, or diploid (2 N), a set of chromosomes, as in the zygota (an egg from which the body develops) as a result of fertilization from each parent falls on a single chromosome set. Therefore, all chromosomes of dialing pairs, homologous - one from the father, the other from the mother. In cells, this set is kept constant due to mitosis.
Sex cells (gamets) - egg cells and spermatozoa (or sperm in plants) - have a single, or haploid, a set of chromosomes (N). This set of gamets is obtained thanks to Mieozu (from the Greek word Meiosis - a decrease). In the process of MEIOS, one doubling of chromosomes and two divisions are taken. - Reducing and equation (equal). Each of them consists of a number of phases: interphalazes, proofased, metaphase, anaphases and elephant (Fig. 1).
In Interfase I (first division), doubling is reduction - chromosomes. Each chromosome after that consists of two identical chromatids connected by one centromer. In PROFARE I, MEIOS, there is a pairing (conjugation) of doubted homologous chromosomes, which form bivalents consisting of four chromatids. At this time, spiralization, shortening and thickening with chromosomes occurs. In the metaphase I, paired chromosomes-homologs are built on the cell equator, in Anafase I, they differ in its different poles, in the body I cell is divided. In each of the two cells after the first division, only one double chromosome falls from each pair of homologous chromosomes, i.e., a decrease (reduction) of the chromosome chromosome is doubled.
After the first division in the cells, short interphase II (second division) is underway without doubling chromosomes. The second division goes like mitosis. In metaphase II chromosomes, consisting of two chromatids, are built on the cell equator. In Anafase II, chromatids diverge to the poles. In Kelofase II, both cells are divided. It has been established that there is a direct relationship between a set of chromosomes in the kernel (2 n or n) and the number of DNA in it (denoted by the letter C). In the DNA diploid cell twice (2c) than in the haploid (C). In an interfass, the diploid cell before preparations for its division, DNA replication occurs, its quantity doubles and becomes equal to 4C. After the first division, the amount of DNA in subsidiaries decreases to 2C, after the second division - to 1C, which corresponds to the chromosome a haploid set.
The biological meaning of Maiz is as follows. First of all, in a number of generations, a set of chromosomes is preserved, which is peculiar to this form, since the fertilization is merged with haploid grounds and the diploid set of chromosomes is restored.
In addition, processes occur in MEIOSE, providing the implementation of the basic laws of heredity: first, due to the conjugation and compulsory subsequent discrepancy of homologous chromosomes, the law of purity of Games is carried out - only one chromosome from a pair of homologues and, therefore, only one allele from the pair - a or a, in or b.
Secondly, the random divergence of non-homologous chromosomes in the first division provides an independent inheritance of signs controlled by genes located in different chromosomes, and leads to the formation of new combinations of chromosome and genes (Fig. 2).
Thirdly, genes located in one chromosome are shipped inheritance. However, they can be combined and forging new combinations of genes as a result of crosslinker - sharing areas between homologous chromosomes, which is carried out with their conjugation in the first division profhae (Fig. 3).
Thus, two mechanisms for the formation of new combinations (genetic recombination) can be distinguished in meyosis: the random discrepancy between the non-homologous chromosomes and the crosslinker.
Mitosis (indirect division) is dividing somatic cells (body cells). The biological value of mitosis is the reproduction of somatic cells, receiving copies (with the same set of chromosomes, with exactly the same hereditary information). All somatic cells of the body are obtained from one source cell (zygotes) by mitosis.
1) PROFADA
- chromatin spiral (twisted, condensed) to the state of chromosomes
- nucleoli disappear
- nuclear shell decay
- centrioles are diverted to the poles of the cell, the spindle divisions are formed
2) metafasa - chromosomes are built on the cell equator, the metaphase plate is formed.
3) Anphasis - Chromosome subsidiaries are separated from each other (chromatids become chromosomes) and diverge to the poles
4) Bulfasa
- chromosomes are despondent (spinning, deconentially) to the state of chromatin
- core and nuclei appear
- filaments spindle division are destroyed
- cytokines occurs - separation of the cytoplasm of the mother cell into two subsidiaries
The duration of mitosis is 1-2 hours.
Cell cycle
This is the period of cell life from the moment of its formation by dividing the maternal cell to its own division or death.
The cell cycle consists of two periods:
- interfhaza (condition when the cell is not divided);
- division (mitosis or).
Interphase consists of several phases:
- pREDITTICAL: Cell grows, it takes active synthesis of RNA and proteins, the number of organoids increases; In addition, there is preparation for DNA doubling (accumulation of nucleotides)
- synthetic: Doubling (replication, reduction) DNA
- postsynthetic: the cell is prepared for division, synthesizes the substance necessary for dividing, such as proteins of the separation of division.
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Tests and tasks
Select one, the most correct option. The process of breeding cells of organisms of different kingdoms of wildlife is called
1) Meiosis
2) Mitozom
3) fertilization
4) fraction
Answer
1. All features below, besides two, can be used to describe the interphase processes of the cell cycle. Determine the two features, "dropping" from the general list, and write down the numbers in the table, under which they are indicated.
1) cell growth
2) the discrepancy of homologous chromosomes
3) Location chromosome by equator cell
4) DNA replication
5) synthesis of organic substances
Answer
2. All features below, except two, can be used to describe the processes occurring in the interfax. Determine the two features, "dropping" from the general list, and write down the numbers in the table, under which they are indicated.
1) DNA replication
2) the formation of a nuclear shell
3) chromosome spiralization
4) Synthesis ATP
5) Synthesis of all types of RNA
Answer
3. The processes listed below, except for two, are used to characterize the cell cycle interphase. Determine two processes, "dropping" from the general list, and write down the numbers under which they are specified.
1) the formation of spindlers
2) Synthesis ATP
3) Replication
4) cell growth
5) Crossinchinger
Answer
Select one, the most correct option. At what stage of the life of the chromosome cells spiral
1) Interfhaza
2) PROFADA
3) Anphasis
4) Metafaza
Answer
Select three options. What cellular structures undergo the greatest changes in the mitosis process?
1) kernel
2) cytoplasm
3) Ribosomes
4) lysosomes
5) Cell Center
6) Chromosomes
Answer
1. Install the sequence of processes occurring in a cell with chromosomes in an interfass and subsequent mitosis
1) Location of chromosomes in the equatorial plane
2) DNA replication and formation of two-sized chromosomes
3) chromosome spiralization
4) the discrepancy between the nursing chromosomes to the poles of the cell
Answer
2. Install the sequence of processes occurring during interphase and mitosis. Record the appropriate sequence of numbers.
1) chromosome spiralization, disappearance of a nuclear shell
2) the discrepancy between the nursing chromosomes to the poles of the cell
3) the formation of two subsidiaries
4) doubling DNA molecules
5) Placing chromosomes in the plane of the equator cell
Answer
3. Install the sequence of processes occurring in the interfax and in mitosis. Record the appropriate sequence of numbers.
1) dissolving the nuclear membrane
2) DNA replication
3) destruction of spindle
4) discrepancy to the poles of single chromosomes cells
5) Education of the metaphase plate
Answer
4. Set the correct sequence of processes occurring during mitosis. Record the numbers under which they are indicated.
1) Disintegration of the nuclear shell
2) thickening and shortening chromosomes
3) Building chromosomes in the central part of the cell
4) the beginning of the movement of chromosomes to the center
5) the discrepancy of chromatide to the poles of the cell
6) Formation of new nuclear shells
Answer
5. Install the sequence of processes occurring during mitosis. Record the appropriate sequence of numbers.
1) chromosome spiralization
2) Chromatide discrepancy
3) the formation of spindle separation
4) Despioralization of chromosomes
5) division of cytoplasm
6) Location of chromosomes at the cell equator
Answer
6. Install the sequence of processes occurring during mitosis. Record the appropriate sequence of numbers.
1) the filaments of the separation of division are attached to each chromosome
2) a nuclear sheath is formed
3) a doubling of centrioles
4) protein synthesis, increase in the number of mitochondria
5) Cellular Center Centrioles Dissolve To Cell Poles
6) chromatids become independent chromosomes
Answer
We form 7:
4) disappearance of filaments spindle division
Select one, the most correct option. When dividing the cells, the formation of the separation of division in
1) PROFADE
2) Bulfase
3) metafhase
4) Anafase
Answer
Select one, the most correct option. In the opposition mitosis does not happen
1) the dissolution of the nuclear shell
2) formation of spindle division
3) doubling chromosomes
4) dissolving nucleols
Answer
Select one, the most correct option. At what stage of the life of chromatide cells become chromosomes
1) Interfhaza
2) PROFADA
3) metafas
4) Anphasis
Answer
Select one, the most correct option. Despioralization of chromosomes when dividing the cell occurs in
1) PROFADE
2) metafhase
3) Anafhase
4) Bulfase
Answer
Select one, the most correct option. In which mitosis phase, the chromatide pair is attached to their center meters to the threads of the separation
1) Anafase
2) Bulfase
3) Profase
4) metafuz
Answer
Set the correspondence between the processes and the mitosis phases: 1) anAphase, 2) of the tiphase. Write down the numbers 1 and 2 in the correct order.
A) a nuclear sheath is formed
B) Nursing chromosomes diverge to the poles of the cell
C) spindle divisions finally disappears
D) chromosomes despirate
E) chromosome centermen disconnected
Answer
Set the correspondence between the characteristics and phases of mitosis: 1) metaphase, 2) of the belly. Record the numbers 1 and 2 in the order corresponding to the letters.
A) chromosome consist of two chromatids.
B) chromosomes are despirate.
C) the filaments of the separation of division are attached to the center of chromosomes.
D) a nuclear shell is formed.
E) chromosomes are built in the equatorial plane of the cell.
E) disappearance disappearance occurs.
Answer
Set the correspondence between the characteristics and phases of the division of the cell: 1) anAphase, 2) metaphase, 3) of the belly. Write down the numbers 1-3 in the order corresponding to the letters.
A) Despiracy of chromosomes
B) number chromosome and DNA 4N4C
C) location chromosome by equator cell
D) discrepancy chromosome to cell poles
E) Connection Center with threads of spindle fission
E) the formation of a nuclear membrane
Answer
All listed features except two are used to describe the mitosis phase shown in the figure. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) disappears nuclear
2) the spindle divisions are formed
3) DNA molecules doubling
4) Chromosomes are actively involved in protein biosynthesis
5) chromosome spirals
Answer
Select one, the most correct option. What is accompanied by chromosome spiralization at the beginning of mitosis
1) the acquisition of a two-terrification structure
2) active participation of chromosomes in protein biosynthesis
3) doubling DNA molecule
4) enhanced transcription
Answer
Install the correspondence between the processes and periods of the interphase: 1) postsynthetic, 2) pretenttical, 3) synthetic. Write down the numbers 1, 2, 3 in the order corresponding to the letters.
A) cell growth
B) Synthesis ATP for the division process
C) Synthesis ATF for replication of DNA molecules
D) proteins synthesis for the construction of microtubule
E) DNA replication
Answer
1. All features listed below, except for two, can be used to describe the mitosis process. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) underlies the cull breeding
2) indirect division
3) Provides regeneration
4) reduction division
5) increasing genetic diversity
Answer
2. All listed features, except for two, can be used to describe mitosis processes. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) Bivalent Education
2) conjugation and crossing
3) the invariability of the number chromosomes in cells
4) the formation of two cells
5) Conservation of the structure of chromosomes
Answer
All listed features except two are used to describe the process shown in the figure. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) Subsidiaries have the same chromosomes with parent cells
2) uneven distribution of genetic material between subsidiaries
3) provides growth
4) the formation of two subsidiaries
5) Direct division
Answer
All the processes listed below, except for two, occur in the process of indirect cell division. Determine two processes, "dropping" from the general list, and write down the numbers under which they are specified.
1) two diploid cells are formed
2) Four haploid cells are formed
3) the division of somatic cells
4) There is a conjugation and crosslinker chromosomes
5) cell division is preceded by one interfacia
Answer
1. Install the correspondence between the stages of the cell life cycle and processes. What is happening during them: 1) interfac, 2) mitosis. Record the numbers 1 and 2 in the order corresponding to the letters.
A) formed spine divisions
B) the cell grows, there is an active synthesis of RNA and proteins.
C) cytokines
D) the number of DNA molecules doubles
E) chromosome spiralization
Answer
2. Install the correspondence between the processes and stages of the cell life cycle: 1) interfac, 2) mitosis. Record the numbers 1 and 2 in the order corresponding to the letters.
A) chromosome spiralization
B) intensive metabolism
C) doubling centrioles
D) the discrepancy between the nursing chromatide to the poles of the cell
E) DNA reduction
E) an increase in the number of organoid cells
Answer
What processes occur in the cell during the interphase period?
1) proteins synthesis in cytoplasm
2) chromosome spiralization
3) Synthesis IRNA in the core
4) Reducing DNA Molecules
5) dissolution of the nuclear shell
6) the discrepancy of the central cell center to the poles of the cell
Answer
Determine the phase and the type of division shown in the picture. Write down the two numbers in the order specified in the task, without separators (gaps, commas, etc.).
1) Anphasis
2) metafasa
3) PROFAZ
4) Bulfasa
5) Mitosis
6) Meiosis I
7) Meiosis II
Answer
All listed signs, except for two, are used to describe the cell life cycle shown in the figure. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) disappears spine divisions
2) chromosome form an equatorial plate
3) A nuclear sheath is formed around chromosomes of each pole
4) the cytoplasm division occurs
5) chromosome spirals and become well visible
Answer
Set the correspondence between the processes and stages of cellular division. Record the numbers 1 and 2 in the order corresponding to the letters.
A) the destruction of the nuclear shell
B) chromosome spiralization
C) the discrepancy of chromatide to the poles of the cell
D) the formation of single chromosomes
E) the discrepancy between the centers to the poles of the cell
Answer
Consider the drawing. Specify (a) the type of division, (b) the division phase, (c) the amount of genetic material in the cell. For each letter, select the appropriate term from the proposed list.
1) Mitz
2) Meiosis II
3) metafas
4) Anphasis
5) Bulfasa
6) 2N4C.
7) 4n4c.
8) N2c.
Answer
All listed features except two are used to describe the cellular structure shown in the figure. Determine the two signs, "dropping" from the general list, and write down the numbers under which they are indicated.
1) Cell division type - Mitosis
2) Cage division phase - Anphase
3) chromosomes consisting of two chromatids are attached to their centromeres to the threads of the separation of division
4) chromosomes are located in the equatorial plane
5) Crossinchinger occurs
Answer
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In the nuclei of immature sex cells as well as the kernels of somatic cells, all chromosomes are paired, a set of chromosomes double (2 N), diploid. In the process of ripening genital cells, a reduction division (meyosis) occurs, in which the number of chromosomes decreases, becomes single (N), haploid. Meiosis (from Greek. Meiosis - Reduction) occurs during gametogenesis.
This process is accomplished during the two following one after another divisions of the ripening period, called the first and second meiotic division, respectively. Each of these divisions has phases similar to mitosis.
Schematically, these phases can be depicted as follows:
Interfaz I.
Proofase I.
Meiosis division first Prometofase I
Metafaza I.
Anphase I.
Bulfase I.
Interfaz II - IN - PROFAZ II
terokinesis metaphase II.
Division second Anphasis II
Bulfase II.
In Interfase I (apparently, during the growth period), the amount of chromosomal material is doubted by the reduction of DNA molecules.
Of all the phases are the most extended and complex according to the processes of Proofase I flowing in it. It distinguishes 5 consecutive stages. Leptonema - the stage of long, thin, weakly spiralized chromosomes, on which the thickening are visible - chromomers.
Zigong - stage of the pairwise compound of homologous chromosomes, in which chromomers of one homologous chromosome are accurately applied to the corresponding chromomers of the other (this phenomenon is called conjugation, or synapse).
Pakhoryema - stage of thick threads. Homologous chromosomes are connected to pairs - bivalent. The number of bivalents corresponds to a chromosome haploid set. At this stage, each of the chromosomes included in the Bivalent consists of two chromatids, so each bivalent includes four chromatids.
At this time, the conjugating chromosomes are intertwined, which leads to the exchange of sections with chromosomes (the so-called crossover is happening, or cross hinge).
Diplonem - stage, when homologous chromosomes begin to repel apart from each other, but in a number of areas where cross hinge, they continue to be still connected.
Diacines - a stage on which the repulsion of homologous chromosomes continues, but they still remain connected to bivalent by their ends, forming characteristic figures - rings and crosses. At this stage, chromosomes are cooled as much as possible, shorten and thickened. Immediately after diakinosis, the nuclear shell dissolves.
In Prometafase I, chromosomes spiralization achieves the greatest extent. They move in the equator area.
In the metaphase I, the bivalents are located on the equator, so that the centering rooms of homologous chromosomes are addressed to the opposite poles and repel each other.
In Anafase, I begin to diverge to the poles not chromatids, but the whole homologous chromosomes of each pair, since, in contrast to mitosis, the centromer is not divided and chromatids are not disconnected. This, the first meiotic division is fundamentally different from mitosis. The division ends with Bulphasis I.
Thus, during the first meiotic division, the discrepancy between homologous chromosomes occurs.
Each subsidiary has a haploid number of chromosomes, but the DNA content is still equal to their diploid set. Following the short interfaz, during which the synthesis of DNA does not occur, the cells enter into a second mastic division.
Proofase II lasts long. During metaphase II chromosomes are built up to the equator, the centrners are divided. In Anafase II, nursing chromatids are sent to the opposite poles. The division ends with Balphase II. After this division of chromatids, which fell into the nucleus of subsidiaries is called chromosomes.
So, during MEIOSE, homologous chromosomes are connected to pairs, then at the end of the first meiotic division, one in the subsidiaries cells are diverted.
During the eventually meiotic division, homologous chromosomes are split and disagree in new subsidiaries. Consequently, as a result of two consecutive meiotic divisions from one cell with a diploid set of chromosomes, four cells with a haploid set of chromosomes are formed. In mature gates, the amount of DNA is twice as smaller than somatic cells.
When forming both male and female sex cells, the same processes occur, although they differ somewhat in the details.
Meaning of meiotic division in the following:
This is the mechanism that is ensured by maintaining the constancy of the number of chromosomes. If there were no reduction of the chromosome number during Gametogenesis, then their number would increase from generation to generation and one of the essential signs of each type would be lost - the constancy of the chromosome number. Genetics spermatogenesis reproduction
With meyosis, a large number of various new combinations of non-homologous chromosomes are formed. After all, in the diploid set, they are double origin: in every homologous pair one of the chromosomes from his father, the other - from the mother.
What happens during meyosis? In the nuclei there are spermatogonia and Ovogony, chromosomes of paternal and maternal origin.
In sperm and egg cells, they form new combinations, and such combinations even with the same number of chromosomes (three pairs) will turn out to be more than depicted.
Consequently, thanks to this mechanism, a large number of new combinations of hereditary information are achieved, namely 2, where n is the number of pairs of chromosomes. Consequently, the body having three pairs of chromosomes, these combinations will be 2, i.e.8; Drosophila with 4 pairs of chromosomes will be 2, i.e.6, and in humans 2, which is 8388608.
In the crossinchinger process, the recombination of genetic material also occurs. Almost all chromosomes entering the grounds have sections occurring both from the initial paternal and originally maternal chromosomes. This achieves an even greater degree of recombination of hereditary material. This is one of the causes of the body's variability, which gives material for selection.
