Symbols to Know for Crosses

• a/a – a is the allele and / represents the two chromatids – there are two alleles for a diploid organism

• a b/a b – two different genes on the same chromosome

• a/a ; b/b – two different genes on different chromosomes ; designated separate chromosomes

• X – symbolizes mating between two different individuals

• X - symbolizes a self cross – when the hermaphrodite worms fertilize their own eggs

• + is the wild type or non-mutant form of a gene

Complementation – Cross 1 making the heterozygous males

Female Parent genotype

Male Parent genotype X

Male gametesFemale gametes

Progeny genotype

Progeny phenotypesand ratios

Complementation – mutations in different dpy genes

Female Parent genotype

Male Parent genotype X

Male gametesFemale gametes

Progeny genotype

Progeny phenotypesand ratios

WHY might there be some Dpy hermaphrodites?

Complementation – mutations in the same dpy gene

Female Parent genotype

Male Parent genotype X

Male gametesFemale gametes

Progeny genotype

Progeny phenotypesand ratios

Why are we looking for Dpy males when the mutations are in the same gene?