How is the number of chromosomes maintained ?

Question

Answer

In a human body cell there is total 23 pairs of chromosomes in which 22 pairs are autosomes and 1 pair is the germ cell or the sexosomes

when there is a interbreeding the chromosomes of human cell goes meiosis which helps in the distribution of 46 chromosomes in 23 only only 23 chromosomes from the male body is allowed to go in the female body and same happens in the female body the chromosomes gets divided and only 23 chromosomes mix with the male chromosomes thus the 46 chromosomes are completed and a perfect human cell is designed thus the number of chromosomes is
maintained

that is 23 from male and 23 from female

Answer

The reproductive organs of sexually reproducing organisms produce gametes (sex cells) by a special type of cell division. In this cell division the chromosome number is halved. That is, the diploid mother cell produces haploid sex cells (gametes) containing only half the number of chromosomes. During fertiuisation, when the haploid male and female gametes Rise, they form a diploid zygote. Thus, the full number of chromosomes is reestablished and the specific chromosome number of a species is maintalned.

i hope it's helpful for us

Answer

Introduction:
The number of chromosomes is maintained through a process known as cell division. During cell division, the chromosomes are replicated and distributed equally to the daughter cells. This ensures that each new cell receives the correct number of chromosomes.

Cell division:
Cell division occurs in two main stages: interphase and mitosis or meiosis.

Interphase:
During interphase, the cell grows, carries out its normal functions, and replicates its DNA. The DNA replication process ensures that each chromosome is duplicated, resulting in two identical sister chromatids held together by a centromere.

Mitosis:
Mitosis is a type of cell division that produces two genetically identical daughter cells. It consists of several phases:

1. Prophase: The chromosomes condense and become visible. The nuclear envelope breaks down, and the spindle fibers form.

2. Metaphase: The chromosomes align at the center of the cell, known as the metaphase plate. The spindle fibers attach to the centromeres of each chromosome.

3. Anaphase: The sister chromatids separate and are pulled towards opposite ends of the cell by the spindle fibers.

4. Telophase: The chromosomes reach the opposite poles of the cell, and new nuclear envelopes form around them. The chromosomes decondense, and the cell begins to divide.

5. Cytokinesis: The cytoplasm divides, resulting in two separate daughter cells, each with an identical set of chromosomes.

Meiosis:
Meiosis is a specialized form of cell division that occurs in reproductive cells to produce gametes (sperm and eggs). It involves two rounds of division, known as meiosis I and meiosis II, and results in the production of four genetically diverse daughter cells.

1. Meiosis I: The chromosomes condense, homologous chromosomes pair up, and crossing over occurs, leading to genetic recombination. The homologous chromosomes separate during anaphase I, resulting in two cells with half the number of chromosomes.

2. Meiosis II: The sister chromatids separate during anaphase II, resulting in four haploid daughter cells, each containing half the number of chromosomes as the parent cell.

Maintaining the correct chromosome number:
To maintain the correct number of chromosomes, several mechanisms are in place:

1. DNA replication: Prior to cell division, the DNA is accurately replicated to ensure that each chromosome has an identical copy.

2. Checkpoints: Throughout the cell cycle, checkpoints monitor the integrity and accuracy of DNA replication, chromosome alignment, and spindle fiber attachment. If any errors or abnormalities are detected, the cell cycle can be paused or halted to allow for repair or apoptosis (cell death).

3. Homologous pairing and segregation: During meiosis, homologous chromosomes pair up and segregate independently, ensuring the distribution of a unique combination of chromosomes to each gamete.

4. Fertilization: When sperm and egg cells fuse during fertilization, the resulting zygote restores the diploid chromosome number by combining the haploid sets from each parent.

Conclusion:
The number of chromosomes is maintained through the processes of DNA replication, accurate chromosome segregation during cell division, and the restoration of the diploid number through fertilization. These mechanisms ensure the stability and integrity of the genome, allowing for proper development and functioning of organisms.

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