DNA REPLICATION AND DNA REPAIR AND RECOMBINATION

DNA Replication

The process of copying DNA molecules with high fidelity and very few errors.

Semi-Conservative Replication

A mechanism of DNA replication where the two strands separate, and each original strand serves as a template for a new strand.

DNA Polymerase

The enzyme responsible for synthesizing new DNA strands during replication.

Helicases

Enzymes that break hydrogen bonds between the two strands of DNA to facilitate replication.

Topoisomerase

An enzyme that relieves supercoiling in DNA as it is being pulled apart during replication.

Single-Strand DNA Binding Proteins

Proteins that stabilize single-stranded DNA during replication and prevent it from re-annealing.

Mutations

Changes in DNA sequence that can occur due to various factors including environmental influences.

Non-Homologous End Joining

A DNA repair mechanism that can fix double-strand breaks without needing homologous sequences.

Recombinant DNA

DNA that has been formed artificially by combining constituents from different organisms.

Base Modifications

Alterations to nucleotide bases, often caused by agents like alkylating agents or radiation.

Translesion DNA Polymerase

A specialized enzyme used for DNA repair that lacks exonuclease activity and can bypass damaged sites.

Deamination

The removal of an amine group from a nucleotide, which can lead to point mutations.

DNA Repair Mechanisms

Processes that correct damage to the DNA structure to maintain genomic integrity.

Alkylating Agents

Chemical compounds that can cause DNA damage by adding alkyl groups to nucleotides.

Pyrimidine Dimer

A form of DNA damage caused by UV radiation where two adjacent pyrimidines bond together.

Sliding Clamp

attaches to DNA polymerase and holds the enzyme onto the DNAstrand

Clamp Loader

Loads clamp onto DNA

What are the causes of DNA changes

1. heat

2. metabolic accidents

3. exposure of radiation

4. exposed to different substances in environment

What is the job for exonuclease?

Exonuclease helps to proof read and decrease DNA polymerase error rate to 1 nucleotide for 10^9 nucleotides synthesized

What are some examples of DNA damage?

1. Base modification- caused by alkylating agents

2. Pyrimidine dimer- caused by UV radiation

3. Deamination to point mutation

4. Depurination

5. Methylation