Homologous Recombination and DNA Repair

This flashcard set covers the mechanisms of homologous recombination in both meiosis and somatic cells, including key structures like Holliday Junctions and processes like gene conversion.

Holliday Junctions

The two junction points that form during meiosis when crossing-over occurs between two homologous chromosomes.

Heteroduplex

The region of DNA between two Holliday Junctions where two strands from homologous chromosomes are hydrogen-bonded together, potentially containing non-identical sequences.

Gene conversion

A process where a cell notices mismatches in a heteroduplex and corrects one strand to match the other, resulting in one allele being converted into the other.

Mendel’s first law (of segregation)

A genetic law violated during gene conversion because the resulting gametes carry the same allele instead of segregating into different ones.

Double-strand breaks

A form of DNA damage that triggers homologous recombination in somatic cells to repair the DNA molecule.

Spo11

A specific protein that intentionally creates double-strand breaks in DNA molecules during meiosis to initiate the crossing-over process.

Homologous chromosomes

The templates used during meiotic recombination to form a heteroduplex, which may contain different alleles at the same locus.

Sister chromatids

The templates used in somatic cell homologous recombination to form a heteroduplex, ensuring the DNA sequence is perfectly identical during repair.