CH 5 Linkage, Recombination and the Mapping of Genes on Chromosomes

These flashcards cover essential terms and concepts related to gene linkage, recombination, and mapping in genetics.

Gene Linkage

The tendency of genes located close to each other on a chromosome to be inherited together.

Recombination

The process by which linked genes are separated by the exchange of genetic material during meiosis.

Parental Gametes

Gametes that carry the same combination of alleles as the parents.

Recombinant Gametes

Gametes that have new combinations of alleles due to recombination.

Test Cross

A breeding experiment used to determine the genotype of an organism by crossing it with a homozygous recessive individual.

Linkage Analysis

A method used to determine the distance between genes on a chromosome based on the frequency of recombination.

Chiasmata

The points where homologous chromosomes crossover during meiosis.

Recombination Frequency

The percentage of recombinant offspring produced in a genetic cross, used to estimate the distance between genes.

CentiMorgan (cM)

A unit of measure for genetic linkage, defined as a 1% recombination frequency.

Tetrad Analysis

The examination of tetrads (groups of four spores) produced by meiosis in fungi to study inheritance patterns.

Syntenic Genes

Genes located on the same chromosome.

Independent Assortment

The random distribution of alleles during gamete formation.

Dihybrid Cross

A genetic cross that considers two traits, involving parents that differ in two characters.

Parental Ditype (PD)

A tetrad in which all spores have parental configurations.

Nonparental Ditype (NPD)

A tetrad where all spores have recombined configurations.

Tetratype (T) Tetrads

Tetrads that contain two parental and two recombinant spores.

Chi-Square Test

A statistical test used to determine if observed progeny ratios differ from expected ratios.

Linkage Group

A group of genes located on the same chromosome and inherited together.

Double Crossovers

Two crossover events that occur in close proximity, which can complicate mapping.

Interference

The phenomenon where a crossover event decreases the likelihood of a second crossover occurring nearby.

Mapping Genes

The process of determining the relative positions of genes on a chromosome.

Three-Point Cross

A genetic cross that includes three genes, allowing for faster and more accurate mapping.

Ordered Tetrads

Tetrads in which the arrangement of spores can indicate the order of genes.

Mendelian Ratio

The ratio of phenotypes expected from a genetic cross, typically 9:3:3:1 for a dihybrid cross.

Autosomal Genes

Genes located on non-sex chromosomes.

Phenotypic Classes

Categories based on observable traits resulting from genetic crosses.

Haploid Organisms

Organisms that have a single set of chromosomes, such as many fungi.

Ascus

A sac-like structure where spores are contained, typically in fungi.

Meiotic Recombination

The process of exchanging genetic material during meiosis, resulting in varied genetic combinations.

Genetic Map

A representation of the arrangement of genes on a chromosome.

Parental and Recombinant Phenotypes

The visible traits (phenotypes) that indicate whether offspring are of parental or recombinant type.

Base Pair

The building blocks of DNA, comprising pairs of nitrogenous bases (adenine-thymine and guanine-cytosine).

Genetic Mosaicism

Presence of genetically different cells in the same organism due to mitotic recombination.