Linkage, Recombination, and Eukaryotic Gene Mapping

These flashcards cover key concepts related to linkage, recombination, and gene mapping in eukaryotic genetics.

Linked Genes

Genes that are located close to each other on the same chromosome and do not assort independently during meiosis.

Independent Assortment

The principle that alleles at different loci segregate independently of one another during gamete formation.

Recombination

The process by which alleles are shuffled into new combinations during meiosis.

Non-recombinant Gametes

Gametes that have the same combinations of alleles as the parents.

Recombinant Gametes

Gametes that have new combinations of alleles due to crossing over.

Principle of Segregation

The principle stating that alleles segregate independently of each other during the formation of gametes.

Crossing Over

A process that occurs during meiosis where homologous chromosomes exchange segments, leading to genetic variation.

Bateson-Saunders-Punnett Experiment

An experiment showing non-independent assortment of traits in sweet peas, producing unexpected ratios.

Complete Linkage

A situation where genes are so close together on a chromosome that no recombination occurs.

Crossover Frequency

The rate at which crossing over occurs between linked genes, affecting the recombination frequency.

Coupling Configuration

A genetic configuration where both wild-type alleles are on one chromosome and both mutant alleles are on the other.

Repulsion Configuration

A configuration where one chromosome has a wild-type allele and a mutant allele.

Three-Point Testcross

A method used to map three linked genes by analyzing the offspring of a testcross.

Recombination Frequency Calculation

(Number of recombinant progeny / Total number of progeny) x 100%.

Map Units (cM)

A unit of measurement for genetic distance equal to a 1% recombination frequency.

Double Crossovers

A rare event where two crossover events occur in the same region between two genes.

Somatic-Cell Hybridization

A method used to determine which chromosome carries a gene of interest by fusing different cell types.

Deletion Mapping

A genetic mapping technique used to identify the location of genes on chromosomes through loss of function.

Fluorescence In Situ Hybridization (FISH)

A molecular technique used to locate specific DNA sequences on chromosomes using labeled probes.

Coefficient of Coincidence

The ratio of observed double crossovers to expected double crossovers.

Interference

The phenomenon where the occurrence of one crossover event reduces the likelihood of another event occurring nearby.

Gametes

Reproductive cells (sperm and eggs) that carry genetic information from each parent.

Testcross

A cross between an individual with an unknown genotype and a homozygous recessive individual.

Homologous Chromosomes

Chromosome pairs, one from each parent, that are similar in shape, size, and gene content.

Genetic Map

A representation showing the arrangement of genes on a chromosome based on recombination frequencies.

Physical Map

A representation of the physical distances (nucleotide distances) between genes on a chromosome.

Crossover

The exchange of genetic material between homologous chromosomes during meiosis.

Pleiotropy

A situation where a single gene influences multiple phenotypic traits.

Genotype

The genetic constitution of an individual, typically referring to the alleles present.

Phenotype

The observable characteristics or traits of an individual resulting from the interaction of genotype and environment.

Sex-linked Genes

Genes located on sex chromosomes, often showing different inheritance patterns in males and females.

Centromere

The region of a chromosome where the two sister chromatids are joined together.

Eukaryotic Gene Mapping

The process of determining the locations of genes on chromosomes in eukaryotic organisms.