Question

a cell in g2 of the cell division cycle contains 20 chromatids. how many centromeres are present in this cell? ○ 10 ○ 20 ○ 30 ○ 40 ○ 80

Explanation:

Step1: Recall the relationship between chromatids and centromeres

In a cell, each chromosome has one centromere. In the G2 phase of the cell cycle, DNA replication has occurred. Each chromosome consists of two sister chromatids attached to a single centromere.

Step2: Calculate the number of centromeres

If there are 20 chromatids, and since each chromosome (with its centromere) has 2 chromatids in G2 (after DNA replication), the number of chromosomes (and thus centromeres) is \( \frac{20}{2}=10\).

Answer:

10