M1: Linkage and Sex Determination Flashcards
Genes located in the same chromosome (linear order)
Linked Genes
Produces only parental gametes in equal proportions
Complete Linkage
Evidence of linkage to one another
Linkage group
Estimation of distance between two genes or loci along the chromosome.
Chromosome Mapping
Percent Recombination and Crossing Over
Directly Proportional
Estimates the genetic distance between genes
Genetic Map
Specifies the physical location and distance between genes
Physical Map
Chromosomes are distinguish between banding patterns and sizes
Cytological Map
Significance of Chromosome Mapping
- difference between species
- understanding segregation and inheritance of genes
- insight to gene function
They developed “crossing over as basis of distance between genes”
Thomas Hunt Morgan & Alfred Sturtevant
Similar to parents or parental gamete
Non-Crossingover Gametes
Exchange between non-sister chromatids in a single tetrad
Single Crossover
Two or more exchanges between non-sister chromatids in a single tetrad
Multiple Crossover
Two separate and independent exchanges must occur simultaneously
Double Crossovers
Conditions for Three-Point Mapping
- Heterozygous in all loci
- Phenotypes of resulting offspring must be observed
- Number of offspring must represent crossover classes