Homologous chromosomes

Homologous chromosomes are a pair with corresponding genes at the same loci, one inherited from each parent. They may carry different alleles and pair during meiosis.

Meiosis: A type of cell division that produces haploid cells from a diploid cell. Homologous chromosomes pair and separate during its first division.
Chromosome: A DNA molecule packaged with proteins that carries genetic information in a cell. Homologues are corresponding members of this DNA-carrying structure.
Sister chromatids: Two nearly identical copies of a replicated chromosome joined at the centromere. They are replicated copies of one chromosome, unlike parental homologues.
Genetic recombination: The production of new genetic combinations through DNA exchange or reassortment. Crossing over between homologues is a major source of recombination.
Synapsis: The close pairing of homologous chromosomes during prophase I of meiosis. It aligns homologues so they can exchange DNA.
Gene: A DNA sequence that contributes to a functional product or regulates its production. Homologues carry corresponding genes at matching positions.
Non-sister chromatids: Chromatids belonging to different homologous chromosomes in a paired set. They are the chromatids that usually exchange DNA during crossing over.
Linkage disequilibrium: The nonrandom association of alleles at different loci in a population. Crossing over between homologues can break down associations between nearby alleles.
Crossing over: The exchange of corresponding DNA segments between chromosomes, commonly between homologues during meiosis. Exchange between paired homologues creates new combinations of alleles.
Locus: The physical position of a gene or other sequence on a chromosome. Matching loci define where corresponding genes occur on homologues.

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