DNA Mutation and Repair

A comprehensive set of flashcards covering key concepts related to DNA mutation and repair.

Mutation

Any change made to the DNA sequence or chromosome structure.

Somatic mutations

Mutations that arise in the DNA of somatic cells, which are not passed to the next generation.

Germ-line mutations

Mutations that arise in the DNA of germ tissue, which are transmitted to offspring.

Lethal mutations

Mutations that are incompatible with life, leading to prenatal death.

Conditioned mutations

Mutations that produce an effect only under certain environmental conditions.

Reversion mutation

A mutation that reverses the effect of a previous mutation.

Base-pair substitutions

Small gene mutations where one nucleotide is changed to a different nucleotide.

Silent mutation

A mutation that has no effect on the amino acid sequence, often occurring at the third nucleotide of a codon.

Missense mutation

A change that causes the wrong amino acid to be inserted into a protein.

Nonsense mutation

A mutation that changes a codon into a stop codon, truncating the polypeptide.

Frameshift mutation

A mutation that involves insertions or deletions, causing a shift in the reading frame.

Expansion of trinucleotide repeats (TNRE)

An abnormal increase in the number of trinucleotide repeats adjacent to or within a gene, often leading to disease.

Lesion

Damage to the structure of a nucleotide.

Apurinic site

A site in DNA where a purine base has been lost, leaving the sugar-phosphate backbone intact.

Deamination

The spontaneous removal of an amino group from a nucleotide base, altering base pairing.

Tautomeric shifts

Temporary shifts in the chemical forms of nitrogenous bases that can lead to improper base pairing.

Free radicals

Atoms or groups of atoms that have unpaired electrons, making them highly reactive and capable of damaging DNA.

Transposons

Genetic elements that can move within a genome and disrupt gene function.

Ames test

A test used to evaluate whether a chemical can cause mutations and potentially lead to cancer.

Direct repair

Repair mechanisms that reverse alterations without cutting or replacing nucleotides.

Excision repair

A type of DNA repair that removes altered bases and replaces them with correct nucleotides.

Mismatch repair

A repair system that fixes mismatches of DNA that appear otherwise normal.

Homologous recombination repair

A repair process that uses a homologous chromosome to repair double-stranded breaks.

Non-homologous end joining

A repair pathway that directly joins two broken DNA ends without the use of a homologous template.

Translesion synthesis

A repair mechanism that allows DNA replication to continue past lesions using specialized DNA polymerases.