Symbols to Know for Crosses

1. 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

2. Hermaphrodite Parent genotype Male Parent genotype X Creating a heterozygous male Female gametes Male gametes Progeny genotype Progeny phenotypes and ratios Which progeny are you continuing with? Why?

3. Linkage 1: Cross with Unlinked unc Hermaphrodite Parent genotype +/+ ; unc/unc Male Parent genotype X Female gametes Male gametes F1 Progeny genotype and ratios F1 Progeny phenotypes

4. Linkage 2: Selfing of hermaphrodite from unlinked cross hermaphrodite self cross X gametes Progeny genotype Progeny phenotypes and ratios

5. Linkage 1: Crossing with Linked unc Hermaphrodite Parent genotype Male Parent genotype + unc/+ unc X Female gametes Male gametes Progeny genotype Progeny phenotypes and ratios Which progeny are you continuing with? Why?

6. Linkage 2: Selfing of hermaphrodite from linked cross hermaphrodite self cross X gametes Progeny genotype Progeny phenotypes and ratios

7. Mapping 1: Making the double mutant hermaphrodite self cross X gametes Progeny genotype Progeny phenotypes and ratios What if the genotype of the parent was + unc/+ unc?

8. Mapping 2: Making heterozygotes for mapping Hermaphrodite Parent genotype Male Parent genotype X Female gametes Male gametes Progeny genotype Progeny phenotypes and ratios Why might you see Dpy Unc progeny?

9. Mapping 3: Test Cross Hermaphrodite Parent genotype Male Parent genotype X Parental Recombinant Female gametes Male gametes Progeny genotype Progeny phenotypes and ratios