linkage, mapping, and sex determination

recombinant

new combinations from parental

unlinked genes

will show 50/50 for parental and recombinant genes

test cross for linkage

crossing heterozygous and homozygous recessive for linkage

coupling

dominant alleles for different genes stay together in parentals

repulsion

dominant alleles for different genes stay apart in parentals

rules of genetic mapping

test cross can only measure up to 50 cM between 2 linked genes but smaller distances can be added

sequential hermaphroditism

both female and male sex

psuedo autosomal regions

only places xy chromosomes can cross over because the sequence is similar enough

xy chromosomes

females are homogametic with XX, males are heterogametic with XY

SRY gene

male determination, normally found on y chromosome

sex determination in drosophila

1:2 ratio of x chromosome to haploid is male, 2:2 ratio is female

XX/X0

females are diploid, males are haploid

ZW chromosomes

females are heterogametic, males are homogametic

reciprocal cross

cross 2 individuals with opposite phenotypes in parental