2 - "Non" Mendelian Genetics - Codominance, Incomplete Dominance, etc., and Linkage

Linkage

The physical association of two or more genes found on the same

chromosome

Linked genes

Predicted to always be transmitted together during gamete formation and should violate the principle of independent assortment

Recombination

Breaking and rejoining of DNA

Crossing over occurs between…

Non-sister chromatids

Linkage mapping

Genetic technique used to determine the relative positions of genes on a chromosome based on how frequently they are inherited together.

Greater physical distance between genes…

Increases the chance that crossing over will occur between them

How far apart do genes have to be to assort independently?

50 or more map units apart on the same chromosome

Dominant alleles

It can determine the organism's phenotype (observable trait) even if only one copy is present; does not necessarily confer high fitness, AND they are not necessarily more common than recessive alleles

Incomplete dominance

Neither allele is completely dominant over the other, resulting in a blended or INtermediate phenotype in the heterozygous individual

Codominance

Both alleles in a heterozygous individual are fully and equally expressed, without blending; both traits appear side by side

Epistasis

One gene affects the action of another gene. In many cases, the alleles at one gene mask or reduce the effects of alleles at a different gene