DNA Replication Flashcards

Vocabulary flashcards for DNA Replication lecture.

Topoisomerase

An enzyme that changes the number of times the two strands in a closed DNA molecule cross each other by cutting, passing DNA through the break, and resealing the DNA.

Replisome

The multiprotein structure that assembles at the bacterial replication fork to undertake synthesis of DNA, containing DNA polymerase and other enzymes.

Conditional lethal

A mutation that is lethal under one set of conditions, but not lethal under a second set of conditions, such as temperature.

dna mutants

Temperature-sensitive replication mutants in E. coli that identify a set of loci called the dna genes.

Repair synthesis

Replaces a short stretch of one strand of DNA containing a damaged base.

5’–3’ exonuclease activity

A unique activity of DNA polymerase I that can be combined with DNA synthesis to perform nick translation. It acts as a 5′–3′ exonuclease.

Nick translation

Replaces part of a pre-existing strand of duplex DNA with newly synthesized material.

Processivity

The ability of an enzyme to perform multiple catalytic cycles with a single template instead of dissociating after each cycle.

Semidiscontinuous replication

The mode of replication in which one new strand is synthesized continuously while the other is synthesized discontinuously.

Helicase

Separates the strands of DNA using energy provided by hydrolysis of ATP.

Single-stranded DNA binding protein

Required to maintain separated DNA strands during replication.

Primase

Synthesizes an RNA chain that provides the priming end for DNA replication.

DnaB

Unwinds DNA for replication in E. coli.

Clamp loader

Places the processivity subunits on DNA, where they form a circular clamp around the nucleic acid.

DNA ligase

Makes the bond that connects the 3′ end of one Okazaki fragment to the 5′ beginning of the next fragment.