Cellular respiration is a series of metabolic reactions essential to all living cells. Respiration releases energy from sugars and stores it in the form of adenine triphosphate (ATP). ATP is the basic energy currency for cell processes.
Respiration can take place in the presence or absence of oxygen (aerobic vs. anaerobic conditions). For yeast, anaerobic respiration is known as fermentation, and produces carbon dioxide along with ethanol or lactate as the primary waste products, while aerobic respiration produces carbon dioxide and water as the primary waste products In this lesson, students will use the scientific method in one instructor-guided experiment and one student-designed experiment to explore cellular respiration in yeast. When yeast is mixed with a sugar source and water, foam forms, and may be measured as a proxy for carbon dioxide production.
By comparing respiration rates between different water temperature and sugar sources, students can determine optimal conditions for yeast respiration. An environment that is too cold, too hot, or lacking in food will result in lowered rates of respiration or death