During asexual reproduction in the unicellular fungus Saccharomyces (yeast), a precise sequence of cellular events leads to the formation and independent release of a daughter cell. What is the correct chronological sequence of these events during the budding process?
- 1Localized enzymatic weakening of the chitinous cell wall and outward protrusion of the cell membrane driven by internal turgor pressure.
- 2Mitotic division of the parent nucleus followed by the migration of one daughter nucleus into the expanding bud.
- 3Deposition of a chitinous septum across the narrow neck constriction separating the parent and daughter cytoplasm.
- 4Enzymatic cleavage of the septum wall and separation of the daughter cell, leaving a permanent chitinous scar on the parent cell.
Answer
The correct chronological sequence of budding in Saccharomyces begins with localized cell wall weakening and protrusion under turgor pressure, followed by nuclear mitosis and migration into the bud, then chitinous septum synthesis at the cell neck, and concludes with cell separation leaving a bud scar.
The budding process in yeast begins when wall-modifying enzymes locally weaken the cell wall, allowing hydrostatic turgor pressure to force out a small protrusion. As this bud grows, the parent nucleus undergoes mitotic division, and one daughter nucleus migrates through the neck into the bud. Following nuclear transfer, chitin synthesizers lay down a primary septum across the neck to seal off both cellular compartments. Finally, chitinase enzymes cleave the connecting wall layers, releasing the independent daughter cell while leaving a prominent chitinous bud scar on the parent.
Step-by-Step Solution
Key Concept
Mechanism of Budding and Cytokinesis in Saccharomyces (Yeast)