Linkage Genes that are physically located on the same chromosome are said to be “linked”. Linked genes are said to be “mapped” to the same chromosome. When two genes are mapped to the same chromosome, the genes will not assort independently during meiosis.

Linked alleles tend to be inherited together.

Crossing over produces new allelic combinations.

Chiasmata are the sites of crossing over.

Crossing over is between chromatids, not chromosomes.

Multiple crossovers can include more than two chromatids.

Recombinants are produced by crossovers.

Independent assortment produces 50% recombinants.

For linked genes, recombinant frequencies are less than 50%.

Map distances are generally additive.

Longer regions have more crossovers and thus higher recombinant frequencies.