AP BIOLOGY

Detailed explanation-1: -T4 gp43 polymerase per se is a distributive enzyme with a dissociation rate constant of 6–8 sec-1 (18). Its processivity is greatly enhanced by the accessory proteins, gp45 and gp44/62 (2, 11).

Detailed explanation-2: -Multiple DNA polymerases have specialized roles in the DNA replication process. In E. coli, which replicates its entire genome from a single replication fork, the polymerase DNA Pol III is the enzyme primarily responsible for DNA replication and forms a replication complex with extremely high processivity.

Detailed explanation-3: -Most DNA polymerases are intrinsically low-processivity enzymes [9, 10] despite some noticeable exceptions, such as the phage 29 DNA polymerase [11]. Processivity is defined as the ability of DNA polymerase to carry out continuous DNA synthesis on a template DNA without frequent dissociation.

Detailed explanation-4: -The major replicative DNA polymerase in E. coli cells is DNA polymerase III holoenzyme (Pol III HE) able to synthesize DNA with high processivity (over 50 kb/binding event) (Yao et al., 2009) and with high speed (up to 1000 nucleotides per second).

Detailed explanation-5: -Polymerase Processivity “Processivity” is a term that refers to the number of nucleotides incorporated by a polymerase in a single binding event (before dissociation). Taq DNA polymerase adds approximately 50 nucleotides per binding event (8).