Experiments 1 and 2: Genetics In order to define potential effects of the presen

Experiments 1 and 2: Genetics
In order to define potential effects of the presence/absence of the Itga7 protein on the
inheritance patterns a number of breedings were performed. The genotypes of the parents
were known and the genotypes of the litters (age: 14-16 days) were analysed by allele-specific
PCR reactions.Experiment 1:(Marks: 10)
In three parallel experiments (1.1 1.2 1.3) crossings of 5 wildtype males (Itga7+/+) with 10
heterozygous females (Itga7+/-) were started and all litters (Total number of mice) were
genotyped and the numbers of all possible genotypes are given in the following Table 1. All
mice tested appear normal and show no altered phenotype at the tested age.
Breeding: m(Itga7+/+) x f(Itga7+/- )
Table 1:
Experiment
1.1
1.2
1.3
Litters
Total number
42
68
70
Genotypes
Itga7+/+
20
32
31
Itga7+/-
22
36
39
Itga7-/-
0
0
0
Corrected version: 19. November 2012
Experiment 2:(Marks: 20)
In three parallel experiments (2.1 2.2 2.3) crossings of 5 heterozygous males (Itga7+/-) with 10
heterozygous females (Itga7+/-) from experiment 1 were started all litters were again
genotyped and the numbers of all possible genotypes are given in the following Table 2.
Breeding: m(Itga7+/-) x f(Itga7+/- )
Table 2:
Experiment
2.1
2.2
2.3
Sum (2.1-2.3)
Litters
Total
55
60
37
Genotypes
Itga7+/+
13
19
13
Itga7+/-
34
33
20
Itga7-/-
8
8
4
Questions to answer:
(A) Discuss briefly which type of genetic inheritance would be most adequate to describe the
distribution of genotypes?
(B) Does the distribution of genotypes (numbers of mice) in experiments 1 and 2 correspond to
the expected numbers according to Mendelian laws?
(C) Are there any further conclusions on phenotypes possible? If yes what could be possible
reasons?