The Inheritance of Mutant Traits

1
The Inheritance of Mutant Traits
Drosophila Culturing
2
Objective
Determine the pattern of inheritance of mutant
traits in Drosophila melanogaster (fruit flies)

• The pattern of inheritance will either show...
• incomplete dominance or reveal the dominant
• and recesssive strains
• sex linkage or autosomal inheritence

3
Why Fruit Flies?
Produce numerous offspring
Takes up little space
Easy to Culture
Many genes to study experiment
New generation every 2 - 3 weeks
Low rate of mutations
4
adult female
adult male
Drosophila Life Cycle
Egg Larva Pupa Adult
5
Sex Determination in Drosophila
Comparing Abdomens
Female
Male
Females large pointed abdomen light
posterior generally larger no sex combs
Males smaller, rounder abdomen dark
posterior generally smaller sex combs
Male Sex Combs
Sex combs on front legs
6
Mutant
Normal
Apterous (mutant)
Winged (wild)
trait
ap apterous or wingless (mutant type)
normal wings (wild type)
alleles
7
P1 Cross
Wild males (normal wings)
Apterous (females) (wingless)
phenotypes
X

ap ap
X
genotypes
normal wings (wild type)
Ap apterous or wingless (mutant type)
8
F1 Cross
What is the dominant trait?
What is the recessive trait?
What of traits will be expressed in the F2?
9
More Mutant Traits
White eyes
Vestigial