Homework 8

These flashcards cover key concepts related to the initiation, elongation, and termination phases of DNA replication in both E. coli and eukaryotic cells, including the proteins involved and their functions.

Initiation Phase

The phase where DNA replication begins at the origin of replication, involving initiator proteins like DnaA and DnaB.

Origin of Replication (OriC)

The specific site in E. coli where DNA replication initiates.

DnaA

The primary replication initiator protein that signals the start of DNA replication.

DnaB

The helicase enzyme that unwinds the DNA strands at the replication fork.

DnaC

A protein that helps guide DnaB helicase in loading onto DNA.

Elongation Phase

The phase of DNA replication where nucleotides are added to the new DNA strand by DNA polymerase.

Leading Strand

The continuously synthesized DNA strand during replication, where DNA polymerase III adds nucleotides.

Lagging Strand

The discontinuously synthesized DNA strand consisting of short RNA Okazaki fragments.

Beta Clamp

A protein that clamps DNA polymerase to the DNA, facilitating continuous synthesis.

DNA Polymerase I

The enzyme that replaces RNA primers with DNA during replication.

Termination Phase

The phase of DNA replication in E. coli where replication stops at specific termination sites.

Tus Protein

The protein that binds to termination sites in E. coli and halts the progression of replication forks.

Topoisomerase

An enzyme that alleviates supercoiling in the DNA ahead of the replication fork by breaking and rejoining DNA strands.

Eukaryotic Replication

Involves multiple origins of replication on each chromosome, unique initiation proteins, and elongation by different polymerases.

DNA Polymerase Alpha

The enzyme in eukaryotes responsible for creating primers during replication.

End-Replication Problem

A phenomenon where DNA polymerase cannot fully replicate the ends of linear chromosomes, leading to DNA loss over time.

Archaeal Replication

Similar to eukaryotic replication but features unique initiation mechanisms and often polyploid chromosomes.

Polymerase Epsilon

A DNA polymerase in archaea that elongates primers on the leading strand.

Polymerase Delta

A DNA polymerase in archaea that elongates primers on the lagging strand.