Lecture 10 Flashcards
Principle of Segregation
Alleles separate during meiosis
Law of Independent Assortment
Alleles at one locus sort independently from alleles at another locus
Recombination
Alleles sort into new combinations
Crossing Over
Complete linkage of alleles leads to nonrecombinant gametes and nonrecombinant progeny; crossing over disrupts linked alleles and leads to recombinant gametes and recombinant progeny
How do you calculate recombination frequency?
Recombination Frequency = (# of recombinations /total # of progeny) x 100
Coupling Configuration (Cis Configuration) of Linked Genes
One chromosome contains both wild-type alleles, one chromosome contains both mutant alleles
Repulsion Configuration (Trans Configuration) of Linked Genes
Wild-type allele and mutant allele are found on the same chromosome
Coefficient of Coincidence
of observed double crossovers/# of expected double crossovers
Interference
1 - Coefficient of Coincidence
Haplotype
Set of DNA variations, or polymorphisms, that tend to be inherited together
Centimorgan
Unit for measuring genetic linkage; abbreviated as cM or map unit (m.u.)
Genetic Maps
Illustrate the arrangement of genes and DNA markers on a chromosome and the relative distances between positions are calculated using recombination frequencies
Physical Maps
Illustrate the arrangement of genes and DNA markers on a chromosome based on the actual number of nucleotide pairs between loci
What is somatic cell hybridization used for?
Used to determine which chromosome contains a gene of interest
What is deletion mapping used for?
Used to determine the chromosomal location of a gene; an individual homozygous for a recessive mutation in the gene of interest is crossed with an individual heterozygous for a deletion
What is fluorescence-in-situ hybridization used for?
Another technique used for determining the chromosomal location of a gene
Genome-wide Association Studies
Examine genetic (sequence) variants across the entire genome to find those that are associated with a trait or a disease; each individual differs by million of sequence variants scattered across the genome; usually identifies variants that are higher in proportion in the study group, so the next step is to establish biological relevance
Variants associated with a trait often occur in noncoding parts of the genome
