Genetic Linkage Flashcards
how can genes on the same chromosome appear to assort independently from each other during gamete formation
they will assort independently when they are far apart from each other
define syntany
genes on the same chromosome that are located so close together that they can not assort independently(linked genes)
define linkage
proximity of 2 or more genes on a chromosome
T/F linked genes can be located on different chromosomes
FALSE
whats the difference between complete linkage and linkage with recombination
complete linkage: no crossover(recombination) occurs between linked genes, the more linked the less recombinance
T/F frequency of genetic exchange between two genes depends on their chromosomal location
TRUE
who constructed the first linkage map? what was the model organism?
Alfred Sturtevant used drosophila
how does distance between 2 loci influence crossing over frequency
as distance increases so does crossing over frequency
what is the recombination frequency equation
R= # of recombinants/total number of progeny
differences between gametes of dihybrid cross of unlinked and linked genes
completely linked dihybrids form only 2 types of gametes with a 1:1 ratio
unlinked can have any combination of genes
can you construct a genetic linkage map using male drosophila? explain?
No, males exhibit complete linkage and have no crossing over
what are criteria for the construction of a genetic linkage map
-all considered loci must be heterozygous
-genotype of all gametes can be determined by phenotypes of offspring
-large number of offspring must be produced to recover all crossover classes
how does map unit(mu) correlate to recombination frequency
1 MU equals 1% recombinancy
what types of markers should should one use for generating linkage maps
DNA markers relative to each other
what is interference in relation to crossing over
reduces expected number of crossovers
-1-C
what is the main cellular/biological event on which linkage map depends
genetic recombination during meiosis
equation for coefficient of coincidence
observed DCOs/expected DCOs
