Drosophila and linkage mapping Flashcards
what is a wild-type allele
the most common allele for each trait in the wild populations
how do we show that something is a dominant mutant allele
starts with an uppercase letter
how do we show that something is a recessive mutant allele
start with a lowercase
how do we show if something was the wild-type allele
has a superscripted +
when we crossed a heterozygous fly with a doubly homozygous mutant fly did we get expected ratio
no, instead we got 90% parental phenotype and 10% recombinant
what did this new ratio/frequency show
that the alleles were connected, on the same chromosome
what is gene linkage
when two genes are close together on the same chromosome they are more likely to be crossed over and transmitted together
if genes are linked why did we get recombinant phenotypes
due to the crossover phase in prophase 1
what are parental gametes
gametes that maintain the original linkage of the alleles int eh chromosome of the parental generation
what are recombinant gametes
gametes where the original linkage is undone due to the exchange of chromosomal pieces
what is genetic recombiantion
a change in the combination of alleles in a given chromosome meiotic product or individual
what is a recombinant
an individual chromosome, meiotic product, or individual that possesses a new combination of alleles due to crossing over
how can we use recombinant frequencies to map the order of genes on chromosomes
the closer the genes are the lower the recombinant frequencies resulting in the testcross with the F1 dihybrid generation
what is one map unit
the distance along a chromosome within which crossing over happens 1% of the time (if it happens 0.107 times then it is 10.7 map units apart)
what happens when the genes are more than 50 map units apart
recombinant frequencies will suggest that the alleles are sorting independently of one another
