Question

For a diploid human cell, state how many copies of each chromosome are present in each cell(or soon to be daughter cell)?a) start of meiosis b)end of mitosis c)start of meiosis d)end of meiosis II

Answer 1

Cell division is an important biological process that results in the formation of daughter cells giving rise to the next generation. Cell division is highly regulated and comprises cytoplasmic division and nuclear division.

Complete answer:
Nuclear division is of two kinds- mitosis and meiosis. Mitosis is the process during which a replicated chromosome gets equally segregated into two daughter cells. Mitosis comprises the following stages-prophase, prometaphase, metaphase, anaphase and telophase. During prophase the cell prepares to undergo division by condensing its chromosome and inducing mitotic spindle formation. During prometaphase microtubules start to assemble that are later used to separate the chromosome into chromatids. During metaphase the chromosomes are arranged on the equatorial plane which is located centrally between two centrosomes.

During anaphase due to shortening of the spindle fibers the chromosomes get pulled to chromatids. During telophase a new nuclear envelope forms and the chromosomes begin to decondense. Meiosis takes place in sexually reproducing organisms giving rise to gametes. Meiosis comprises meiosis I and meiosis II phases. Meiosis I is referred to as reductional division as the number of chromosomes becomes half. It comprises the same four phases of mitosis, difference lies in the prophase I phase during which crossover occurs resulting in chiasmata formation and also helps in stable pairing between chromosomes and efficient segregation. Meiosis II is exactly similar to mitosis and known as the equational division where the sister chromatids generated in meiosis I segregate forming four haploid daughter cells.

So for a diploid human cell copies of each chromosome present are-a) start of mitosis-46 b) end of mitosis-46 c) start of meiosis- 46 d)end of meiosis II- 23 .

Note: Both mitosis and meiosis are important cell division processes. Mitosis not only helps in generation of daughter cells for the next generation but also helps to replenish damaged cells. Meiosis helps in the production of the male and female gamete that ultimately help in reproduction and production of offspring.