What is the number of chromosomes after meiosis 2?
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Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction. During reproduction, when the sperm and egg unite to form a single cell, the number of chromosomes is restored in the offspring. Show Meiosis begins with a parent cell that is diploid, meaning it has two copies of each chromosome. The parent cell undergoes one round of DNA replication followed by two separate cycles of nuclear division. The process results in four daughter cells that are haploid, which means they contain half the number of chromosomes of the diploid parent cell. Meiosis has both similarities to and differences from mitosis, which is a cell division process in which a parent cell produces two identical daughter cells. Meiosis begins following one round of DNA replication in cells in the male or female sex organs. The process is split into meiosis I and meiosis II, and both meiotic divisions have multiple phases. Meiosis I is a type of cell division unique to germ cells, while meiosis II is similar to mitosis. Meiosis I, the first meiotic division, begins with prophase I. During prophase I, the complex of DNA and protein known as chromatin condenses to form chromosomes. The pairs of replicated chromosomes are known as sister chromatids, and they remain joined at a central point called the centromere. A large structure called the meiotic spindle also forms from long proteins called microtubules on each side, or pole, of the cell. Between prophase I and metaphase I, the pairs of homologous chromosome form tetrads. Within the tetrad, any pair of chromatid arms can overlap and fuse in a process called crossing-over or recombination. Recombination is a process that breaks, recombines and rejoins sections of DNA to produce new combinations of genes. In metaphase I, the homologous pairs of chromosomes align on either side of the equatorial plate. Then, in anaphase I, the spindle fibers contract and pull the homologous pairs, each with two chromatids, away from each other and toward each pole of the cell. During telophase I, the chromosomes are enclosed in nuclei. The cell now undergoes a process called cytokinesis that divides the cytoplasm of the original cell into two daughter cells. Each daughter cell is haploid and has only one set of chromosomes, or half the total number of chromosomes of the original cell. Meiosis II is a mitotic division of each of the haploid cells produced in meiosis I. During prophase II, the chromosomes condense, and a new set of spindle fibers forms. The chromosomes begin moving toward the equator of the cell. During metaphase II, the centromeres of the paired chromatids align along the equatorial plate in both cells. Then in anaphase II, the chromosomes separate at the centromeres. The spindle fibers pull the separated chromosomes toward each pole of the cell. Finally, during telophase II, the chromosomes are enclosed in nuclear membranes. Cytokinesis follows, dividing the cytoplasm of the two cells. At the conclusion of meiosis, there are four haploid daughter cells that go on to develop into either sperm or egg cells. Meiosis IIChromosomal replication does not occur between meiosis I and meiosis II; meiosis I proceeds directly to meiosis II without going through interphase. The second part of the meiosis, meiosis II, resembles mitosis more than meiosis I. Chromosomal numbers, which have already been reduced to haploid (n) by the end of meiosis I, remain unchanged after this division. In meiosis II, the phases are, again, analogous to mitosis: prophase II, metaphase II, anaphase II, and telophase II (see figure below). As shown in the figure below, meiosis II begins with two haploid (n = 2) cells and ends with four haploid (n = 2) cells. Notice that these four meiocytes are genetically different from one another. In humans (2n = 46), who have 23 pairs of chromosomes, the number of chromosomes remains unchanged from the beginning till the end of meiosis II (n = 23). Prophase II Spindle fibers reform and attach to centromeres in prophase II. Metaphase II The chromosomes align on the metaphase plate during metaphase II in preparation for centromeres to divide in the next phase. Anaphase II In anaphase II, chromosomes divide at the centromeres (like in mitosis) and the resulting chromosomes, each with one chromatid, move toward opposite poles of the cell. Telophase II and Cytokinesis Four haploid nuclei (containing chromosomes with single chromatids) are formed in telophase II. Division of the cytoplasm during cytokinesis results in four haploid cells. Note that these four cells are not identical, as random arrangements of bivalents and crossing over in meiosis I leads to different genetic composition of these cells. In humans, meiosis produces genetically different haploid daughter cells, each with 23 chromosomes that consist of one chromatid. These haploid cells become unfertilized eggs in females and sperm in males. The genetic differences ensure siblings of the same parents are never entirely genetically identical. What happens to the chromosomes after meiosis 2?Meiosis I is followed by meiosis II, which resembles mitosis in that the sister chromatids separate and segregate to different daughter cells. Completion of meiosis II thus results in the production of four haploid daughter cells, each of which contains only one copy of each chromosome.
What is the number of chromosomes after meiosis 1?Each daughter cell will have half of the original 46 chromosomes, or 23 chromosomes. Each chromosome consists of 2 sister chromatids. The daughter cells now move in to the third and final phase of meiosis: meiosis II. At the end of meiosis I there are two haploid cells.
How many chromosomes are in the human cells after meiosis I and meiosis II?23 chromosomes are present in the human cell during meiosis. A typical diploid human cell contains 23 pairs of chromosomes; 46 total, half of maternal origin and half of paternal origin. Meiosis produces haploid gametes with one set of 23 chromosomes.
How many chromosomes are at the end of meiosis?Each daughter cell will have four chromosomes at the end of meiosis. The phase represented in the diagram is of Metaphase II of Meiosis II, during Anaphase II, sister chromatids are moved to opposite poles, with each pole/then the cell will have 4 chromatids/chromosomes.
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