Question

The epithelial cells in the skin of an animal have 48 chromatids in G2. How many chromosomes are present in the gametes of this animal?

Answer 1

The epithelial cells in the skin of an animal have 48 chromatids in G2 phase. We know, 1 chromosome contain 2 chromatids. Therefore, chromosome number in G2 phase = 48/2 = 24 chromosome. After fertilization, chromosome number in G1, S and G2 phase has no change. Only in S phase, amount of DNA doubled, but chromosome number remaining same. Therefore, after fertilization in zygote chromosome number is also 24. In zygote, half of the chromosome comes from parental gamete and remaining half of the chromosome comes from maternal gamete. Therefore, gametes of this animal contain 24/2 = 12 chromosomes.