1. Consider a hypothetical locus for tuberculosis resistance/susceptibility with

Question

1. Consider a hypothetical locus for tuberculosis resistance/susceptibility with alleles Tr (resistant) and Ts (susceptible). When exposed to the tuberculosis pathogen, TrTr individuals survive 80% of the time, and TsTs individuals survive 20% of the time. What is the value for survival percentage of TrTs individuals if the locus exhibits:
                  a. additive gene action?
                  b. complete dominance and Tr is the dominant allele?
                  c. complete dominance and Ts is the dominant allele?
                  d. partial dominance and Tr is the dominant allele?
                  e. overdominance and Ts is the dominant allele?

Explanation / Answer

a.In case of TrTr individuals,survival percentage=80%=0.8 so,frequency of Tr gene=0.8/2=0.4

TsTs individuals,survival percentage=20%=0.2 so,frequency of Ts gene=0.2/2=0.1

In case of additive gene action,both genes are working together and exert their effects against pathogen(tuberculosis)=0.4+0.1=0.5=50% is survival percentage.

b.In case of complete dominance,Tr is dominant allele and Ts is suppressed.so, survival percentage of TrTs individuals is 0.4 which is the frequency of Tr gene i.e.40%

c.In case of complete dominance, Ts is dominant allele and Tr is suppressed.so, survival percentage of TrTs individuals is 0.1 which is the frequency of Ts gene i.e.10%

d.In case of partial dominance, Both genes are responsible for survive against that pathogen.so,the survival percentage is 0.5 i.e.=50%

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