Biology 2601L: Yeast Fermentation

Yeast

A unicellular fungus that is a versatile laboratory microorganism; grows rapidly and have simple nutritional requirements

Facultative anaerobe

An organism that is capable carrying out aerobic (in the presence of O2) respiration, but is also able to switch to fermentation when O2 is not present

Aerobic Respiration

Able to grow or metabolize only in the presence of molecular oxygen

Fermentation

Does not require molecular oxygen to produce useable energy for cellular function

Aerobic respiration in yeast

Yeast cells will use O2 if it is present breaking sugars down completely to CO2 and H2O

Fermentation in yeast

If O2 is absent, yeast will switch to an alternative pathway to break down sugar molecules into energy (alcohol fermentation); produces CO2 and ethanol