DNA Replication and Enzymology

Vocabulary flashcards covering the enzymes and mechanisms involved in DNA replication based on lecture notes.

Helicase

Unwinds and unzips the DNA molecule by breaking the hydrogen bonds between the bases, forming a replication bubble at the origins of replication.

Topoisomerase

Makes a transient double-stranded break in the DNA molecule ahead of the replication fork and then reseals it to prevent the formation of supercoils.

Single-stranded DNA binding protein

Binds to and stabilises separated DNA strands to prevent them from reannealing and degradation.

Primase

Catalyses the synthesis of an RNA primer by complementary base pairing to initiate the synthesis of a polynucleotide.

DNA polymerase III

Adds dNTPs to the RNA primer in the $5'$ to $3'$ direction by complementary base pairing, using an active site specific to the $3'$ OH end of nucleotides.

Phosphodiester bond formation

The process where DNA polymerase III links the $3'$ OH end of a growing DNA strand to the $5'$ phosphate group of an incoming dNTP.

Pyrophosphate

A group lost from an incoming dNTP during replication; the release of energy from this process is coupled to phosphodiester bond formation.

DNA polymerase I

Hydrolyzes the RNA primer and replaces it with deoxyribonucleotides by complementary base pairing.

DNA ligase

Catalyses the formation of phosphodiester bonds between the Okazaki fragments of the lagging strand.

Prokaryotic origin of replication

Due to a small genome size, prokaryotic cells require only one origin of replication.

Eukaryotic origin of replication

Because the DNA molecule is very large, many origins are present to increase the rate of DNA replication.

Semiconservative replication

The result of DNA replication where each daughter DNA molecule consists of one parental and one newly synthesised daughter strand.