Question

The number of chromosomes in G${}_1$ phase of cell cycle is 24. What will be the number of chromosomes in the G${}_2$ phase?

• A. 24
• B. 12
• C. 48
• D. 6

Answer 1

The correct option is A 24

Cell undergoes cell cycle which includes a sequene of events during which the cell replicates its genetic material and then undergoes division. The cell cycle includes two phases - interphase and mitotic phase.

Interphase is a non dividing phase and includes G${}_1$, S and G${}_2$ phases in sequence. Cell divides during mitotic phase.

The DNA undergoes replication during S phase and after which the total content of DNA doubles. The chromosome will now have two chromatids but the chromosome number does not increase and will remain the same as in G${}_1$ phase.

After S phase, the cell enters into G${}_2$ phase and during this phase, proteins needed for cell division are synthesised but with respect to DNA no changes occur. Hence, the cell in G${}_2$ phase will have the same number of chromosomes as in G${}_1$ and S phase.

As per the question given here, the cell has 24 chromosomes in G${}_1$ phase and the number shall remain same during
G${}_2$ phase also. Hence, the cell at G${}_2$ phase will have 24 chromosomes.