HL DNA Replication Guided Notes

DNA replication

The process of copying the genome within a cell to create two identical DNA molecules.

Semi-conservative replication

A type of DNA replication where each new double-stranded DNA has one strand from the original DNA.

Helicase

An enzyme that binds to the origin of replication and unzips the DNA double helix by breaking hydrogen bonds.

Replication fork

The region where the original DNA double helix splits into two strands.

Single strand binding proteins

Proteins that bind to single-stranded DNA to prevent the strands from rejoining by stopping hydrogen bonds from reforming.

Gyrase

An enzyme that moves in front of helicase to relieve tension ahead of the replication fork.

DNA Polymerase III

An enzyme that reads the template strand and synthesizes the complementary DNA strand in a 5’ to 3’ direction.

Primase

An enzyme that synthesizes a short RNA primer to provide a starting point for DNA Polymerase III.

Okazaki fragments

Short sections of DNA synthesized on the lagging strand during DNA replication away from the replication fork.

Ligase

An enzyme that catalyzes the formation of phosphodiester bonds between Okazaki fragments, creating a continuous DNA strand.

Polymerase Chain Reaction (PCR)

A technique used to amplify small fragments of DNA, effectively simulating DNA replication in a test tube.

Taq polymerase

A heat-stable DNA polymerase enzyme originally found in prokaryotes that live in hot springs, used in PCR.

Gel electrophoresis

A method for separating DNA fragments based on size using an electric current through a gel.

Restriction enzymes

Enzymes that cut DNA molecules at specific sequences to create manageable fragments for gel electrophoresis.

DNA fingerprints

Unique patterns created by restriction enzyme cut sites when DNA samples are run through a gel, used for identification.

Single nucleotide polymorphisms (SNPs)

Variations at a single nucleotide position in DNA that can change cut sites of restriction enzymes.