Which cellular process does not initiate during the S phase?

Which cellular process does not initiate during the S phase?

• A. Cohesin activity
• B. Condensin activity
• C. Histone duplication
• D. Centrosome duplication

Answer: (B)

The S phase, or synthesizing phase, of the cell cycle is characterized by specific activities essential for DNA replication and preparation for cell division. During this phase, the primary focus is on DNA synthesis, which involves the replication of chromosomes. Cohesin activity is crucial in holding sister chromatids together after the DNA has been replicated. This is important for ensuring that the chromatids remain paired until they are ready to be separated during mitosis. Histone duplication also occurs in the S phase because histones are the proteins around which DNA wraps, and new histones are required to package the newly synthesized DNA into chromatin. Centrosome duplication happens during the S phase as well, as the centrosome is responsible for organizing the microtubules that will separate the chromosomes during mitosis. Each daughter cell needs a centrosome to properly organize its spindle apparatus. Condensin activity, however, typically does not begin until the prophase of mitosis. While condensins are essential for the proper condensation of chromatin into distinct chromosomes, they are activated later in the cell cycle and are not involved in the processes that occur during the S phase. Therefore, the correct answer indicates the cellular process that remains inactive during the S phase, aligning with the

The S phase, or synthesizing phase, of the cell cycle is characterized by specific activities essential for DNA replication and preparation for cell division. During this phase, the primary focus is on DNA synthesis, which involves the replication of chromosomes.

Cohesin activity is crucial in holding sister chromatids together after the DNA has been replicated. This is important for ensuring that the chromatids remain paired until they are ready to be separated during mitosis.

Histone duplication also occurs in the S phase because histones are the proteins around which DNA wraps, and new histones are required to package the newly synthesized DNA into chromatin.

Centrosome duplication happens during the S phase as well, as the centrosome is responsible for organizing the microtubules that will separate the chromosomes during mitosis. Each daughter cell needs a centrosome to properly organize its spindle apparatus.

Condensin activity, however, typically does not begin until the prophase of mitosis. While condensins are essential for the proper condensation of chromatin into distinct chromosomes, they are activated later in the cell cycle and are not involved in the processes that occur during the S phase. Therefore, the correct answer indicates the cellular process that remains inactive during the S phase, aligning with the