Two yeast cells, one of type a and the other of type α, are in proximity to each other. The a yeast cell has a mutation in the gene for the α factor receptor protein such that the receptor does not translocate to the plasma membrane of the a cell. If both cells secrete their respective a and α factors, which of the following outcomes is most likely to occur?
A) The a and α cells will grow toward each other.
B) The a cell will grow towards the α cell, but the α cell will not grow toward the a cell.
C) The α cell will grow toward the a cell, but the a cell will not grow towards the α cell.
D) The a and α cells will not grow toward each other at all.

Question

Quizplus · Accepted Answer

In yeast, the α factor binds to its receptor on a yeast cell with the a mating type and triggers a signaling cascade that induces growth towards the α cell. Similarly, the a factor binds to its receptor on a yeast cell with the α mating type and triggers growth towards the a cell. The mutation in the gene for the α factor receptor protein in the a yeast cell prevents it from responding to the α factor and growing towards the α cell. However, the α cell can still respond to the a factor and grow towards the a cell. Therefore, option C is the most likely outcome.

Two Yeast Cells, One of Type a and the Other