Question

You mate a haploid yeast with a slow growth phenotype due to a cellular metabolic defect with a haploid wild-type yeast, resulting in a diploid cell. Without knowing the genome sequence of the yeast, or the sequence of the mutations, how might you determine if the mutation is in the nuclear or mitochondrial genome

Answer 1

As we all know that yeast is a unicellular organism (a fungus) which has a asexual mode of reproduction and that through mitosis hence resulting in the production of two identical daughter cells.

Now, it can enter a meiotic pathway and thus form either spores or haploid cells providing the mother cell is diploid. The two haploid cells can mate and become diploid.

Now according to the question, if there is a mutation in yeast cell it will result in the exclusion of protein needed for biosynthesis which can no longer survive in growth medium.

1 gene co-relates to 1 protien and the genotype is often shown in its phenotype, find mutants which do not detect odour/ smell.

Lets provide a simple example here.

As we look at arginine biosynthesis yeast model:

• we mutaginize these cells in liquid
• do replica plating
• screening
• selecting the desired colonies
• Now take the Master Plate and use a sterile transfer device to make a replica plate and incubate it.
• Store the master plate in clean enviroment to avoid contamination.
• Do the Test of recessivity
• Do the test of complementation
• Do the test of epistasis in order to detect whether the mutation is in nuclear genome or mitochondrial genome.