Question

The starting cell must duplicate its Chromosomes in interphase before mitosis can being? Does this change the number of chromosomes? Chromatids? both? how many of each would you expect in a human cell after interphase

Answer 1

Answer:

The correct answer is both.

Explanation:

• Each chromosome is made up of a pair of sister chromatids which remain attached to each other at the centromere.
• During DNA replication the DNA duplicates, which means that if initially in the parent cell 'n' chromosomes were present then, after duplication, the number of chromosomes in the cell will be '2n'.
• As mentioned above, each chromosome has a pair of sister chromatids, that is, two chromatids per chromosome. So, 'n' chromosomes will have '2n' chromatids. Hence, '2n' chromosomes will have '4n' chromatids.
• In a parent cell,

1. Before duplication, number of chromosome = n, number of chromatid = 2n.
2. After duplication, number of chromosome = 2n, number of chromatid = 4n.

• The cell cycle proceeds as, G0, G1, S, G2, M.
• G0 represents the interphase. It occurs before replication or duplication of the chromosomes, which occurs in the S phase.
• So, in G0 phase, the chromosome number is 'n' and chromatid number is '2n'.