Fungal genetics — mating in budding yeast (Saccharomyces cerevisiae) In haploid yeast cells used in genetics and biotechnology, what are the names of the two mating types (often informally called “genders”)?

Introduction / Context:
Yeast genetics relies on controlled mating between haploid cells. Saccharomyces cerevisiae, the classic budding yeast of baking and biotechnology, has two haploid mating types that fuse to form diploids. Knowing their correct names is fundamental for strain construction, mapping, and laboratory crosses.

Given Data / Assumptions:

• The organism of interest is budding yeast (Saccharomyces cerevisiae).
• Haploid “genders” are technically called mating types.
• We are asked to choose the correct names used in genetics protocols and literature.

Concept / Approach:

S. cerevisiae has two haploid mating types designated a and alpha (often written as α). Cells of opposite mating type secrete and respond to complementary pheromones (a-factor and α-factor), allowing shmoo formation and cell fusion. Diploid cells (a/α) subsequently undergo mitosis or, under starvation, meiosis and sporulation to generate haploid spores of both mating types. The lower-case letters are conventional and important for clarity in protocols and genotype notation.

Step-by-Step Solution:

Verification / Alternative check:

Genetics texts and yeast handbooks consistently denote mating types as a and α. Lab strains are labeled MATa or MATα, and diploids are MATa/MATα, reinforcing the accepted nomenclature.

Why Other Options Are Wrong:

“M and F” suggests animal sexes, not yeast. “Y(a) and Y(b)” is nonstandard and misleading. “A and Alpha (capital A)” is incorrect formatting; the field uses lower-case a and α.

Common Pitfalls:

Mixing case or substituting human-like sex labels for microbial mating types. Also, confusing the greek letter alpha with the Latin letter “a”.

Final Answer:

a and alpha (α)