Ch. 7 Linkage, Recombination, & Eukaryotic Gene Mapping Flashcards
linked genes
genes located close together on the same chromosome
linkage group
a group of linked genes
nonrecombinant (parental) gamete
gamete that contains only the original combinations of alleles present in the parents
nonrecombinant (parental) progeny
progeny that possess only the original combinations of traits possessed by the parents
recombinant gamete
gamete that possesses new combinations of alleles
recombinant progeny
progeny formed from recombinant gametes that possess new combinations of traits
recombination frequency
proportion of recombinant progeny produced in a cross
coupling (cis) configuration
arrangement of linked genes in which the wild-type alleles of two or more genes are on one chromosome and their mutant alleles are on the homologous chromosome
repulsion (trans) configuration
arrangement of two linked genes in which each of a homologous pair of chromosomes contains one wild-type (dominant) allele and one mutant (recessive) allele
genetic map
map of the relative distances between genetic loci, markers, or other chromosome regions determined by rates of recombination; measured in recombination frequencies or map units
physical map
map of physical distances between loci, genetic markers, or other chromosome segments; measured in base pairs
map unit (m.u)
unit of measure for distances on a genetic map; also called a centiMorgan. 1 map unit equals a recombination frequency of 1%
centiMorgan (cM)
a map unit
two-point testcross
cross between an individual heterozygous at two loci and an individual homozygous for recessive alleles at those loci
three-point testcross
cross between an individual heterozygous at three loci and an individual homozygous for recessive alleles at those loci
interference
degree to which one crossover interferes with additional crossovers
coefficient of coincidence
ratio of observed double crossovers to expected double crossovers
mapping function
mathematical function that relates recombination frequencies to actual physical distances between genes
lod (logarithm of odds) score
logarithm of the ratio of the probability of obtaining a set of observations, assuming a specified degree of linkage, to the probability of obtaining the same set of observations with independent assortment; used to assess the likelihood of linkage between genes from pedigree data
genetic marker
any gene or DNA sequence used to identify a location on a genetic or physical map
linkage analysis
gene mapping based on the detection of physical linkage between genes, as measured by the rate of recombination in the progeny of a cross
genome-wide association study
a study that looks for nonrandom associations between the presence of a trait and alleles at many different loci scattered across a genome - that is, for associations between traits and particular suites of alleles in a population
haplotype
a specific set of linked genetic variants or alleles on a single chromosome or on part of a chromosome
linkage disequilibrium
nonrandom association between genetic variants within a haplotype
single-nucleotide polymorphism (SNP)
a single-base-pair difference in DNA sequence between individual members of a species
somatic-cell hybridization
fusion of somatic cells of different types
cell line
genetically identical cells that divide indefinitely and can be cultured in the laboratory
heterokaryon
cell possessing two nuclei derived from different cells through cell fusion
deletion mapping
technique for determining the chromosomal location of a gene by studying the association of its phenotype or product with particular chromosome deletions
