What is Meiosis? Functions, Stages, and Examples of Meiosis

What is Meiosis
What is Meiosis

What is Meiosis? Functions, Stages, and Examples of Meiosis

MEIOSIS

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What is Meiosis?

Meiosis is a process in eukaryotic, sex-breeding animals that reduces the number of chromosomes in a cell before reproduction. Many organisms package these cells into gametes such as eggs and sperm. The gametes can later mate during breeding and form a new zygote. As the number of alleles decreases during meiosis, combining the two gametes will give the zygote the same number of alleles to the parent. In diploid organisms, it is two copies of each gene.

Meiosis is the process by which a cell divides twice to form four cells that contain half of the genetic information. These cells are our sex cells – sperm in men and eggs in women.

 

What are the functions of meiosis?

What are the functions of meiosis?

Many sexually reproductive animals, like their parents, require meiosis to ensure equal numbers of chromosomes in their offspring. In the process of fertilization, the two cells form a new pair. If the number of pairs of each gene in zygotic producing gametes is not less than 1, then the offspring will have 4 copies of each gene. It can give rise to developmental disorders in many animals.

Among other organisms, polyploidy is common, surviving with multiple copies of the same gene. However, if the organism is polymorphic and cannot survive, then meiosis must occur before reproduction. Meiosis occurs in two different divisions, each in different stages.

 

How many stages of meiosis?

How many stages of meiosis?

Meiosis can be divided into nine stages. When the cell first divides its called meiosis I and then divides a second time it’s called meiosis II:

Meiosis I

  1. Interface:
  • DNA is copied into the cell, resulting in two identical complete chromosomes.
  • Outside the nucleus? There are two centrosomes, each containing a pair of centrioles, are these structures important for the cell division process?
  • During the interface, microtubules extend from these centers.
  1. Prophase I:
  • The copied chromosomes are compressed into X-shaped structures that can be easily observed under a microscope.
  • Each chromosome has two genetic chromatics
  • Because chromosomes are coupled, two copies of chromosome 1 together, and two copies of chromosome 2 together, and so on.
  • The pair of chromosomes can then move bits of DNA in a process called recombination or crossover.
  • At the end of profile I, the membrane surrounding the nucleus of the cell dissolves and leaves the chromosome.
  • The meiosis spindle, which contains microtubules and other proteins, extends between the centrioles throughout the cell.
  1. Metaphase I:
  • At the center of the cell (equator), the chromosome pairs align with each other.
  • The centrioles are now at opposite poles of the cell from which the myotic spindle extends.
  • The fibers are attached to the meiosis spindle in the chromosome of each pair.
  1. Anaphase I:
  • The pair of chromosomes is separated using a myotic axis, which draws one chromosome to one pole of the cell and the other to the opposite pole.
  • In meiosis, I have sister chromatids standing together. This is different from what happens in mitosis and meiosis II.
  1. Telophase I and cytokinesis:
  • The chromosomes carry out motions at opposite poles of the cell.
  • At each pole of the cell, a group of chromosomes converge.
  • A membrane is formed on each chromosome to form two new nuclei.
  • A single cell is pinned in the middle to form two separate daughter cells, each containing a set of chromosomes within a nucleus. This process is called cytokines.

Meiosis II

  1. Prophase II:
  • Now, it has two daughter cells, each with 23 chromosomes (23 pairs of chromatids).
  • In each of the two daughter cells, the chromosomes shrink back into visible X-shaped structures that can be easily viewed under a microscope.
  • Membrane chromosomes are released around the nucleus in each daughter’s cell.
  • Duplicate of centrioles.
  • The meiosis axis re-forms.
  1. Metaphase II:
  • In two daughter cells, chromosomes (paired sister chromatics) line up from end to end along the equator of the cell.
  • The centrioles are now opposite the poles in each daughter’s cell.
  • The fibers in the meiosis spindle at each pole of the cell bind to each sister chromatids.
  1. Anaphase II:
  • The sister pulls the chromatid to the opposite poles due to the action of the myotic spindle.
  • Isolated chromatids are now individual chromosomes.
  1. Telophase II and cytokinesis:
  • Chromosomes complete their movement at the opposite poles of the cell.
  • A set of chromosomes attaches to each pole of the cell.
  • A membrane is formed around each new chromosome and two new cell nuclei are formed.
  • Although cell division is not complete without another round of cytokines, this is the final stage of meiosis.
  • After the completion of cytokines, there are four grandchildren, each containing half a set (haploid) chromosomes:
  • In males, all four of these cells are sperm.
  • In females, one of the cells is an egg cell and the other three are polar objects (small cells that do not develop into eggs).

 

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What are the examples of meiosis?

  • Human meiosis

Human meiosis occurs in the genitals. The male testicles produce sperm and the female ovaries produce eggs. However, before these games can be made, the DNA must be reduced. Humans have 23 different chromosomes, 46 chromosomes in homologous pairs between maternal and paternal DNA. Prior to meiosis, DNA replicates in the cell and produces 46 chromosomes in 92 sister chromatids. Each pair of sister chromatids has a corresponding (maternal or ancestral) sister chromosome. These pairs are called homologous chromosomes. During meiosis I, they divide and divide into homologous chromosomes. It leaves 23 chromosomes in each cell, with sister chromosomes on each chromosome. These chromatids can no longer be the same because I may have undergone meiosis during metaphase I, and eventually, meiosis II occurs, and the sister chromatids divide into individual cells. It leaves 4 cells, each containing 23 chromosomes or 4 haploid cells.

  • Fruit flies

Fruit bees have 4 pairs of chromosomes or 8 chromosomes in normal cells. Before meiosis occurs, each chromosome repeats, leaving 8 chromosomes and 16 sister chromosomes. There is meiosis, and there are 2 cells, each with only 4 chromosomes. Each chromosome is still joined by sister chromatids, and some crossing may occur during metaphase I. Meiosis II now occurs in those two cells. In total, 4 cells regenerate. However, these cells have 4 chromosomes. The two gametes combine to form a new fruit fly, with the resulting zygote having 4 pairs and 8 pairs of sister chromosomes, 4 from each parent.

 

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