AP BIOLOGY

Detailed explanation-1: -A DNA double helix is always anti-parallel; in other words, one strand runs in the 5’ to 3’ direction, while the other runs in the 3’ to 5’ direction.

Detailed explanation-2: -The nucleic acid sequences are complementary and parallel, but they go in opposite directions, hence the antiparallel designation. The antiparallel structure of DNA is important in DNA replication because it replicates the leading strand one way and the lagging strand the other way.

Detailed explanation-3: -DNA and RNA are synthesized in the 5′-to-3′ direction.

Detailed explanation-4: -The strands of a DNA double helix are said to be “antiparallel” because the have the same chemical structure, but are opposite in direction.

Detailed explanation-5: -The DNA strands have the opposite orientation: one strand is in the 5′ to 3′ direction with respect to the carbon atoms on the sugar (deoxyribose) and the complementary strand is in the 3′ to 5′ direction (Figure 1(a)).