Synthesis of Histone Proteins

Histones are the highly alkaline proteins found in the eukaryotic cell nucleus. They are the basic structural units of chromatin, which is the complex of DNA and histones that make up chromosomes.

Synthesis of histone proteins occurs during the S phase of interphase, which is the phase of the cell cycle when DNA replication occurs. Therefore, the correct answer is option B.

Interphase

Interphase is the longest phase of the cell cycle, accounting for about 90% of the total time. It is divided into three sub-phases: G1 phase, S phase, and G2 phase.

During the G1 phase, the cell grows and prepares for DNA replication. The S phase is when DNA replication occurs, and the G2 phase is when the cell prepares for cell division.

Histone Synthesis

Histones are synthesized during the S phase of interphase, along with DNA replication. The synthesis of histones is tightly regulated, as the ratio of histones to DNA must be maintained for proper chromatin structure and function.

Histone genes are transcribed by RNA polymerase II, and the resulting mRNAs are translated on ribosomes. The newly synthesized histones are then assembled into nucleosomes, which are the basic building blocks of chromatin.

In addition to their role in chromatin structure, histones also play a role in gene regulation, DNA repair, and other cellular processes. Therefore, proper synthesis and regulation of histone proteins are crucial for cell survival and function.