This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?

Question

The two chromatids were formed by fertilization, bringing together maternal and paternal chromatids.
The two chromatids were formed by duplication of a chromosome.
The two chromatids were formed by synapsis and the formation of a synaptonemal complex.

Answer 1

The correct answer is: The two chromatids were formed by duplication of a chromosome.

During the cell cycle, specifically in the S phase (synthesis phase), each chromosome is duplicated, resulting in two identical copies called sister chromatids that are joined at the centromere. This is distinct from processes like fertilization or synapsis, which involve the combination or pairing of chromosomes rather than duplication.