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  4. In a mammalian cell, the longest and the most active phase of the cell cycle is

Q. In a mammalian cell, the longest and the most active phase of the cell cycle is

 1567  187 Cell Cycle and Cell Division Report Error

Solution:

For amammalian cell growing in culture with a generation time of 16 hours, the different periods would be as follows :
G1 = 5 hours, S= 7 hours, G2 = 3 hours, and mitosis = 1 hour.
So, S phase is the longest phase in a mammalian cell division. It is also the most active phase. In S-phase (synthetic phase), the chromosomes replicate, the DNA content doubles and duplicate set of genes are formed.A long with replication of DNA new chromatin fibres are formed which,however, remain attached in pairs and the number of chromosomes does not increase. Sub units of kinetochores are also synthesised.