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. This makes it necessary for the two new strands, which are also antiparallel to their templates, to be made in slightly different ways.

Detailed explanation-2: -DNA is always synthesized in the 5’-to-3’ direction, meaning that nucleotides are added only to the 3’ end of the growing strand. As shown in Figure 2, the 5’-phosphate group of the new nucleotide binds to the 3’-OH group of the last nucleotide of the growing strand.

Detailed explanation-3: -DNA replication goes in the 5’ to 3’ direction because DNA polymerase acts on the 3’-OH of the existing strand for adding free nucleotides.

Detailed explanation-4: -Specifically, RNA polymerase builds an RNA strand in the 5’ to 3’ direction, adding each new nucleotide to the 3’ end of the strand. RNA polymerase synthesizes an RNA strand complementary to a template DNA strand.

Detailed explanation-5: -Each end of DNA molecule has a number. One end is referred to as 5’ (five prime) and the other end is referred to as 3’ (three prime). The 5’ and 3’ designations refer to the number of carbon atom in a deoxyribose sugar molecule to which a phosphate group bonds.