AP BIOLOGY

Detailed explanation-1: -Recall that DNA is replicated during the S phase of the cell cycle. Thus during metaphase of mitosis, each chromosome (i.e., each chromatid pair) will contain two molecules of double stranded DNA (one molecule per sister chromatid).

Detailed explanation-2: -Answer and Explanation: Immediately after cell division, the chromosomes will be double stranded. Chromosomes are, in effect, never single stranded. Before a cell divides, it replicates its DNA, synthesizing new strands to complement each of the original two strands in a chromosome.

Detailed explanation-3: -Within cells, chromatin usually folds into characteristic formations called chromosomes. Each chromosome contains a single double-stranded piece of DNA along with the aforementioned packaging proteins. Figure 1: Chromatin condensation changes during the cell cycle.

Detailed explanation-4: -A chromatid is one of the two identical halves of a chromosome that has been replicated in preparation for cell division. The two “sister” chromatids are joined at a constricted region of the chromosome called the centromere.

Detailed explanation-5: -Chromosomes appear as long coiled structures at the beginning of prophase and appear as single-stranded. Each chromosome is actually double-stranded due to duplication of genetic material during interphase that precedes mitosis.