Question

Explain how signaling is involved in ensuring that yeast cells fuse only with cells of the opposite mating type.

Short answer

Each yeast cell of the mating-type (a and α) secretes signal molecules that bind to the receptors present on the opposite cells type. In this way, one mating type can only mate opposite mating type as the signal released by sex cells can only be bound to the receptor of the opposite sex cell.

Step-by-step solution

Meaning of cell signaling

The way by which cells communicate with each other is called cell signaling. It involves the transmission of information from one cell to the other cell. The transmission occurs through signals, factors, or hormones.

Cell signaling is a critical process that is required for cell growth, division, differentiation, development, and so on. It is also essential to coordinate various functions of multi-cellular organisms.

Opposite mating-type yeast cells

Yeast Saccharomyces cerevisiae has two types of mating cells. This means these two are the two sexes of the yeast cells. These are called a mating type and α mating type.

For mating, mating types secrete specific signals that are recognized by the opposite mating type. Thus, mating in S. cerevisiae occurs through cell signaling.

Mating in yeast through cell signaling

In yeast, sex cells identify cells of opposite sex types through chemical signaling. The a mating-type release a factor or signal, whereas the α mating-type releases the α factor or signal.

For initiating the mating process, a mating type releases a factor that binds to the receptor present on the α mating type. Similarly, the α factor released by α mating-type binds to the receptor of a mating type.

This means a factor cannot bind to the receptor of a mating type, and the α factor cannot bind to the receptor of the α mating type. Thus, the specific factor released by mating cells ensures that they mate with a cell of the opposite sex.