Genetic linkage

TASK 1:

What genotypes can we expect in gametes, if there is incomplete linkage of genes A and B in gametogony with genotype AaBb?

TASK 2:

What is the phenotype ratio in B1 generation resulting from crossing:

AB x ab
ab ab

Genetic linkage p(AB) = 16.6 cM and number of offspring n = 1152.

TASK 3:

In hens, feathery legs are dominant over featherless (gene A), pea comb over simple (gene B) and white color over dark (gene C). What is the order of genes ABC and power of linkage between neighbouring genes based on genetic analysis of offspring (n = 2500) resulted from test crossing: AaBbCc x aabbcc. Draw chromosome map.

Test crossing:

ABC x abc
abc abc
Phenotypes
ABC
abc
ABc
abC
Abc
aBC
AbC
aBc
Frequency in offspring (%) 80.9 3.9 14.6 0.6

TASK 4:

What is the order of the four genes K, L, N and S and power of linkage (distance) between neighbouring genes located on 5. chromosome of tomato? (K-red color, k-yellow; L-rounded shape, l-sharp; N-pilous stalk, n-bare; S-straight leaf, s-curly). Phenotype frequencies (%) of offspring resulted from test crossing are in tables. Use three-point cross and draw chromosome map of all four genes.

Phenotypes
NKS
nks
NkS
nKs
Nks
nKS
nkS
NKs
% 67.8 29.2 2.2 0.8
Phenotypes
KSL
ksl
kSl
KsL
KSl
ksL
Ksl
kSL
% 49.6 21.4 20.4 8.6