Gene Mutation and DNA Repair Flashcards

Flashcards about Gene Mutation and DNA Repair

Mutation

An altered DNA sequence that can give rise to variability between genes.

Somatic Mutations

Mutations that occur in body cells and cannot be passed to offspring.

Germ Cell Mutations

Mutations that occur in gametes or their stem cells and can be passed to offspring.

Spontaneous Mutations

Mutations that arise naturally from normal cellular processes.

Induced Mutations

Mutations that arise from the influence of exogenous factors.

Base Substitution

Change in a single base pair.

Missense Mutation

Mutation that changes a codon to a different amino acid.

Nonsense Mutation

Mutation that changes a codon to a stop codon, resulting in a shortened protein.

Silent Mutation

Mutation that changes a codon for the same amino acid, resulting in no change in the protein.

Frameshift Mutation

Insertions or deletions that alter the coding sequence of mRNA exons.

Loss of Function Mutation

Mutation that causes the mutated gene to lose or decrease its function or expression.

Gain of Function Mutation

Mutation that causes the mutated gene to increase its function, gain a new function, or increase its expression.

Spontaneous mutations

Arise naturally from normal cellular processes

Induced mutations

Arise from the influence of exogenous factors

Replication Errors

Errors made during DNA replication that can give rise to point mutations, insertions, or deletions.

Tautomeric Shift

Spontaneous repositioning of a hydrogen atom within a molecule, causing a change in the molecule’s structure and potentially leading to mispairing.

Depurination

When a purine base (adenine or guanine) is broken off from nucleotide, giving rise to an "apurinic site" in DNA.

Deamination

When an amino group is removed from a molecule, specifically cytosine, converting it to uracil.

Mutagens

Environmental factors that cause DNA mutations.

Alkylating agents

Add an alkyl group to nucleotides which alters their base-pairing.

Adduct-forming agents

Chemicals that covalently bond to nucleotides and block DNA replication and repair.

Pyrimidine Dimers

Covalent bond formation between pyrimidines.

DNA Repair

Identification and restoration of damaged DNA

Proofreading

DNA polymerase monitors whether it has placed the correct nucleotide in the growing DNA strand.

Mismatch Repair

Corrects mismatched base pairs that bypassed proofreading by DNA polymerase.

Base Excision Repair

Replaces irregular bases in DNA

Nucleotide Excision Repair

Main repair mechanism that fixes DNA damaged by UV radiation

Homology Directed Repair

Carried out when there’s a double-strand break in a chromosome

Ames test

A common method to test whether a chemical can mutate DNA.

Salmonella strain

Special strain of bacteria that requires the amino acid histidine to grow and lacks many DNA repair genes

Insertions

when an extra nucleotides are added to a gene

deletions

when nucleotides are removed from a gene.