Question

In a diploid MATA / MATalpha  yeast strain, what would be the phenotype caused by a missense mutation that prevents the a1 protein from interacting with the alpha2 protein? (Select all that apply.)

A. ability to mate with MAT alpha cells

B. sterility – inability to mate with either cell type

C. ability to mate with MATA cells

D. haploid-specific genes would be expressed

Answer 1

MATa and MATA alpha are the genes which produce protein a and protein alpha respectively

this 2 protein interact with each other and haploid cell get fused to form a diploid cell

yeast cell can be haploid or diploid, the diploid cell has both MATa and MATA alpha are the genes

here the yeast cell is diploid

so it has MATa /MATalpha on MAT locus of homologous chromosome

if the missense mutation (is the point mutation by which the codon change for another amino acid) occurred then here the protein a 1 is defective but protein alpha is normal and the cell now will act as haploid cell even it has dipod set of chromosome

A. ability to mate with MAT alpha cells is this will not be the phenotype cause this cell will lose the ability to mate with MAT alpha cell as it having MAT alpha gene

B ability to mate with MAT alpha cells this will not be the phenotype cause this cell can act as a haploid cell having MAT alpha protein and can fuse with MATa cell

C. ability to mate with MATA cells this will be the phenotype this cell will mate with MATA cell cause it having MAT alpha gene

D. haploid-specific genes would be expressed this will be the phenotype as only MAT alpha gene will be expressed and the cell will act as a haloid cell