Question

genetics peoblem. need help with a-c drawing are helpful too

Question 9) You isolated 7 mutations (m1 through m7) that cause yeast to be defective in synthesizing the amino acid Lysine. By performing complementation tests, epistasis tests, and feeding experiments, you determined that the compounds ASP, THD, and DAP are converted to Lysine by enzymes G, A, and E, and you assigned your mutations to genes. Your results are shown here: THDDAPLysine 2 mutations (m1 and m3) are in the G gene. 3 mutations (m2, m6, and m7) are in the A gene. 2 mutations (m4, m5) are in the E gene. a) (7 points) Fill in the white squares in the complementation table that provided evidence for assigning the 7 mutations to 3 genes. Use+for complementation, and for failure to complement. m1 m2 m3 m4 m5m6 m1 m2 m3 Im m5 m6 b) (6 points) Fill in the epistasis results that provided evidence for the order of genes in the pathway Circle 1: ASP or THD or DAP or Lys ASP or THD or DAP or Lys ASP or THD or DAP or Lys m1 m2 double mutants accumulate m1 m4 double mutants accumulate m2 m4 double mutants accumulate c) (6 points) Fill in the feeding results that confirmed the order of genes in the pathway Circle all compounds that can feed the mutant ASP THD DAP Lys ASP THD DAP Lys ASP THD DAP Lys m1 mutant cells can be fed by m2 mutant cells can be fed by m4 mutant cells can be fed by

Answer 1

a) Complementation test

If you look at the mutations that are specific for a gene you can get the groups of complementarity

so the three groups are

group A with m1 and m3

group B with m2, m6 and m7

group c with m4 and m5

so mutations of the same group will not complement each other (-) and a mutant phenotype will be expressed

while mutations in the different group can complement each other (+) to give a normal phenotype

      m1 m2 m3 m4   m5 m6 m7

m1 -       +     -     +     +     +    +

m2          -     +     +    +     -     -

m3                -       +    +     +   +

m4                        -     -      +    +

m5                              -      +     +

m6                                     -       -

m7                                             -

The epistatic test results

m1 m2 double mutant cannotproduce THD or DAP however it can produce Lysine by using the split products available in the exogenous environment

thus similarly m1 m4 double mutant can produce DAP

m2 m4 double mutant can produce THD

Feeding test results

m1 mutant can be crossfed by THD, DAP and Lys but not with ASP

m2 mutant cn be fed with DAP and Lys

m4 mutant can be fed with Lys only