If a cell has 20 chromosomes, what will be the chromosome number at each of the following stages:

Question

a.) interphase

b.) prophase

c.) metaphase

d.) anaphase

e.) telophase before cytoplasmic division

f.) telophase after cytoplasmic division

Answer 1

DNA replication during Interphase does not change the number of chromosomes, it just creates chromsomes that have a replicated half.

So, in G1 of Interphase it has 20 unreplicated chromsomes.  During S stage of Interphase, the chromosomes are replicated.  In G2 of Interphase there are still only 20 chromsomes, but they are replicated.

In Prophase and Metaphase the chromatids are still together and therefore you still have 20 chromsomes.  

In Anaphase, the chromatids are pulled apart, making two chromosomes for each one.  And, in Telophase before cytoplasmic division, you still have these 2 copies of each chromsome.  So, in these two stages, you have 40.

In Telophase after cytoplasmic division, each of the two new cells has 20 chromosomes.

Answer 2

40-in interphase after S phase.

40- in prophase & metaphase.

40-in early anaphase .

40- in telophase before cytoplasmic division.

20-in telophase after cytoplasmic division.