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At what stage of the cell cycle are histone proteins synthesized in a eukaryotic cell -
A
During telophase
B
During S-phase
C
During G-2 stage of prophase
D
During entire prophase
Detailed Solution
The interphase of the cell cycle has three phases: $G_1$, S and $G_2$.
During the S (synthesis) phase, DNA replication takes place and the amount of DNA per cell doubles.
The newly replicated DNA must be packed into nucleosomes, so new histone proteins are needed at the same time.
Histone synthesis is therefore coupled with DNA replication and occurs mainly during the S phase.
During prophase and telophase the chromosomes condense and decondense, but histones are not synthesised in large amounts.
So histone proteins are synthesised during the S-phase.
During the S (synthesis) phase, DNA replication takes place and the amount of DNA per cell doubles.
The newly replicated DNA must be packed into nucleosomes, so new histone proteins are needed at the same time.
Histone synthesis is therefore coupled with DNA replication and occurs mainly during the S phase.
During prophase and telophase the chromosomes condense and decondense, but histones are not synthesised in large amounts.
So histone proteins are synthesised during the S-phase.