Week 9 - Nonmendelian Genetics Flashcards
(26 cards)
Crossover
The exchange of genetic material between homologous chromosomes during meiosis, leading to genetic recombination.
Independent Assortment
The principle that different genes segregate independently of one another during meiosis, increasing genetic diversity.
Linkage
The tendency of genes located close together on the same chromosome to be inherited together because they do not assort independently.
Parental Allele Combinations
The allele combinations found in the original parent organisms that are passed down without being reshuffled by recombination.
Recombinant (Novel) Allele Combination
New allele combinations that result from crossing over, differing from those found in the parental generation.
Map Unit/Recombination Rate
A measure of genetic distance between loci, where 1 map unit (centimorgan) corresponds to a 1% recombination frequency.
Linkage Distance
The distance between two genes on a chromosome, usually expressed in map units; the greater the distance, the higher the likelihood of recombination.
Parental Generation (P Generation)
The first generation in a genetic cross, whose offspring form the F1 (first filial) generation.
Test Cross
A cross between an organism with an unknown genotype and a homozygous recessive organism to determine the unknown genotype.
Rate of Recombination
The frequency at which crossing over occurs between two linked genes, determining how often new allele combinations arise.
Unlinked Loci
Follow Mendelian independent assortment, with a 50% recombination frequency.
Linked Loci
Recombination frequency is less than 50%, depending on the genetic distance between loci.
Locus
The specific physical location of a gene on a chromosome.
Gene
A unit of hereditary information consisting of DNA that codes for a protein or functional RNA.
Trait
A characteristic or feature of an organism, determined by genetic and environmental factors.
Allele
A variant form of a gene that can lead to different traits (e.g., blue vs. brown eye color alleles).
Gene Interactions At One Locus (one trait)
How alleles at a single gene locus affect the expression of a trait.
Co-Dominance
A form of inheritance in which both alleles are fully expressed in a heterozygote (e.g., AB blood type).
Incomplete Dominance
A form of inheritance where the heterozygote has an intermediate phenotype between the two homozygous phenotypes (e.g., red and white flowers producing pink flowers).
Gene Interactions At Two Loci (one trait)
How genes at two different loci interact to influence a single trait.
Epistasis
A form of gene interaction where one gene masks or modifies the expression of another gene at a different locus.
Gene Interactions at Multiple Loci (one trait)
The influence of multiple genes in determining a single trait.
Polygenic Trait
A trait controlled by multiple genes, leading to continuous variation (e.g., height, skin color).
Role of the Environment
Environmental factors influence the expression of genetic traits (e.g., nutrition affecting height, temperature affecting fur color in animals).
