BIOL 310 Genetic Chapter 7 Flashcards

A set of vocabulary flashcards covering the principles of genetic linkage, crossing over, and methods for genetic mapping based on the BIOL 310 Chapter 7 curriculum.

Gene linkage

Two or more genes that do not independently assort and are instead transmitted together because they are on the same chromosome and in close proximity to each other.

Linkage groups

A term used to describe chromosomes, as they contain a group of genes that are physically linked together.

Bateson and Punnett's Dihybrid Cross

An experiment involving flower color and pollen shape that showed $F_2$ ratios different from expected independent assortment proportions, leading to the discovery of linked genes.

Non-recombinant (parental) cells

Cells or gametes that have the same allele combination as the parents because crossing over did not occur between the genes.

Recombinant (non-parental) cells

Cells or gametes that possess a new combination of alleles different from the parents, resulting from a crossing over event.

Genetic mapping

The determination of the linear order and distance of separation among linked genes on the same chromosome.

Map distance formula

$$\text{Map distance} = \frac{\text{Number of recombinant offspring}}{\text{Total number of offspring}} \times 100$$

Map unit (mu)

The unit of measure for the distance between genes on a chromosome, calculated based on the frequency of recombinant offspring.

Distance and Crossing Over Likelihood

The principle that genes farther apart on the same chromosome are more likely to undergo crossing over, resulting in more recombinant offspring.

Three-factor cross

A test cross involving three genes (such as body color $y$, wing length $m$, and eye color $w$) used to uncover gene order and map distance.

Double crossover

Two crossover events occurring separately between three genes, which identifies which gene is located in the middle and occurs with the lowest frequency in offspring.

Parental phenotypes (linked assortment)

The phenotypes that occur most frequently in the offspring of a linkage cross.

Single crossover

A crossover event involving two genes that occurs at an "intermediate" frequency compared to parental and double crossover phenotypes.