DNA replication outcome in G2 phase

Steps:

• In G1 phase, each chromosome consists of one chromatid with a single DNA molecule.
• During S phase, DNA replication occurs, duplicating each chromatid into two sister chromatids.
• Each sister chromatid contains one identical DNA molecule.
• By the end of G2 phase, each chromosome has two sister chromatids, thus two DNA molecules.

Why C is correct:

• DNA replication in S phase produces two identical DNA molecules per chromosome, forming sister chromatids that persist through G2, as defined by the cell cycle's synthesis phase.

Why the others are wrong:

• A: Centrioles are microtubule-organizing centers in the cytoplasm, not components of chromosomes.
• B: Each chromosome has only one centromere, which joins the two sister chromatids.
• D: Each chromosome always has two telomeres (one at each end), unchanged by replication.

Final answer: C