Question

Part A.
During interphase, chromosomes look a bit different than they do during mitosis. Why is that?

What happens during S-phase of the cell cycle and What happens during the G2 phase of the cell cycle to prepare a cell for mitosis. After reviewing, how many chromosomes are present in this cell during G2?

Answer 1

Interphase is the prepratory phase cell cycle where DNA replicates and formation of essential proteins for the m phase. Interphase is the intermediate phase between two mitotic phase. The main difference between interphase and M phase chromosome is the interphase chromosome are are less condensed as compared to M phase because in interphase DNA has to replicate and transcription translation has to take place so to make it easier enzymes for access to chromosome easily so that protein expression can take place the main function of M phase is is to to divide nuclei into 2 functional daughter nucleus following cytokinesis .

S phase/synthetic phase

This is the second phase of interphase . It is characterized by replication of DNA Or duplication of DNA synthesis of histone proteins. Euchromatin part of chromosome replicate early and heterochromatin part replicate late.

Duplication of centriole pair occurs and new pair of centriole is formed.

Amount of DNA get double in Sphase of cell cycle.

2C---------->4C

Where Cvalue=DNA amount

While change occur only in DNA amount but no change in chromosome number.

Chromosome number remain2 n throughtout mitotis.

G2 phase:

This is characterized by increase in volume of the cell. Mitochondria and plastids undergo division and synthesis of RNA and protein take place for the next phase of cell cycle. Particularly this phase involves the synthesis of tubulin protein for the organisation of spindle fibre.

After G2 phase chromosome number of cell is 2n.

Throughout mitosis chromosome number remain constant.