Genetics and Mapping

Flashcards covering concepts of recombination, linkage, and three-point mapping.

Crossover

Crossover between non-sister chromatids during meiosis results in the exchange of genetic material.

Recombinant Gametes

Gametes that result from a crossover event where genes have been exchanged between chromosomes.

Double Crossovers

Multiple crossover events between genes where the location of the crossovers determines the effect on gene combinations.

Recombination Frequency

The frequency at which crossing over occurs between linked genes; measured in centimorgans or map units and represents the physical distance between genes on a chromosome.

Centimorgan

A unit of measure for genetic linkage; equivalent to 1% recombination frequency. Also referred to as map unit.

Independent Assortment

When genes are located on different chromosomes or are far apart on the same chromosome, they assort independently of each other during meiosis.

Three-Point Cross

A genetic cross involving three genes to determine the distances between genes and their order on a chromosome.

Pure Breeding Individuals

Individuals with a homozygous dominant or recessive trait

Test Cross

Cross between an organism with an unknown genotype and an organism that is homozygous recessive; used to determine the unknown genotype.

Linked Genes

The tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction

Interference

The phenomenon where one crossover event influences the likelihood of another crossover event in a nearby region of the chromosome.

Coefficient of Confidence

The ratio of observed double crossovers to expected double crossovers, indicating the degree of interference.