AP BIOLOGY

Detailed explanation-1: -One of the key molecules in DNA replication is the enzyme DNA polymerase. DNA polymerases are responsible for synthesizing DNA: they add nucleotides one by one to the growing DNA chain, incorporating only those that are complementary to the template.

Detailed explanation-2: -DNA polymerase enzymes cannot begin a new polynucleotide chain by linking two nucleoside triphosphates together. Instead, they absolutely require a base-paired 3′-OH end of a primer strand on which to add further nucleotides (see Figure 5-4).

Detailed explanation-3: -DNA polymerase is responsible for the process of DNA replication, during which a double-stranded DNA molecule is copied into two identical DNA molecules. Scientists have taken advantage of the power of DNA polymerase molecules to copy DNA molecules in test tubes via polymerase chain reaction, also known as PCR.

Detailed explanation-4: -The enzyme that synthesizes DNA, DNA polymerase, can only add nucleotides to an already existing strand or primer of DNA or RNA that is base paired with the template. An enzyme, DNA polymerase, is required for the covalent joining of the incoming nucleotide to the primer.

Detailed explanation-5: -After the primer is in place on a single, unwound polynucleotide strand, DNA polymerase wraps itself around that strand, and it attaches new nucleotides to the exposed nitrogenous bases. In this way, the polymerase assembles a new DNA strand on top of the existing one (Figure 3).