Template 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
Creating a heterozygous male
Hermaphrodite Parent genotype
Male Parent genotype
X
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
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
gametes
Progeny genotype
Progeny phenotypes and ratios
7
Mapping 1 Making the double mutant
hermaphrodite
self cross
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