Question

In a certain organism, a 2n somatic cell that is in G2 phase of the cell cycle contains 64 picograms of DNA. How much DNA would you expect to find in gamete cell from this organism?

Answer 1

2n-diploid cell(somatic cell)

n-haploid cell(gamete)

Mitosis-the number of chromosomes remains the same(2n), during meiosis chromosomes divide into half to produce two gametes(n).

After the S phase (synthesis phase), the number of chromosomes remains the same as the amount of DNA is doubled. During mitotic division, G2(second gap phase) comes after the S phase, at this stage the DNA has doubled, so the somatic cell of this organism(2n) will have half the amount of DNA=64/2=32 picogram of DNA without any change in the number of chromosomes.

Gamete formation occurs after meiotic division wherein chromosome becomes half as well as DNA amount is half of that in a somatic cell. Therefore DNA in gamete = 32/2=16 picogram.