Question

If a parental cell that is 2n=20; 6pg of DNA

How many chromosomes does it have in

G1

S phase

G2

Metaphase

Anaphase

Also what is the genetic content for all the 5 phases

Please explain your answer !

Thank you

Answer 1

Stage	number of chromosomes	genetic content
G1	20	6
S	40	12
G2	40	12
Metaphase	40	12
Anaphase	80	12

See the difference between unreplicated and replicated chromosomes -

CHROMOSOME chromatids sister chromatids DUPLICATED CHROMOSOME centromere

1 chromosome is either 1 chromatid (unreplicated chromosome) or 2 chromatids (replicated chromosome).

The amount of DNA in G1 phase is 6 pg. After DNA replication in S phase it will be doubled to 12 pg. It will remain equal to 12 pg till cytokinesis is achieved and the cell divides to give rise to two daughter cell each having 6 pg DNA.

Similarly, initially the cell is having 60 chromosomes. All chromosomes contain single chromatid. After DNA replication each chromosome will contain two chromatids but there will be 60 chromosomes only. This will remain 60, till metaphase. In anaphase sister chromatids separate and there will be two sets of 60 chromosomes on each of the opposite poles. Now each pole contains 60 chromosomes and after cytokinesis daughter cells with 60 unreplicated chromosomes will be formed.

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