Investigating CO2 Production of Yeast
Objective
The experimental objective of this lab is to observe the effects of certain environmental conditions on the activity of microorganisms in a batch process. Activity will be determined by measuring production of carbon dioxide (CO_2) by rehydrated yeast in each batch and qualitative observations of the turbidity and buoyancy of the batch mixture. Predictions will be made regarding the effects of variables (acidity, alkalinity, electrolyte concentration, and substrate molecule) within the batch mixture on the yeast’s activity, and then be evaluated for validity after the batches are observed.
Overview
The use of yeast or other biological agents, such as proteins or recombinant DNA, to form useful products is an example of biotechnology. A growing field, biotechnology has led to a number of important scientific milestones; for example, in 2020, the scientists who discovered CRISPR-Cas9, an enzyme that allows gene editing, won the Nobel Prize. Their work has allowed for innovations in fields such as healthcare and agriculture. This lab provides an elementary introduction to biotechnology by investigating the reactions of yeast, a microbial fungal species commonly used to convert substrate into valuable products, like bread and alcohol.
Cellular Respiration
Yeast is a species of single-celled fungus. Fungal cells, like plant and animal cells, are eukaryotic; they contain membrane bound organelles and genetic material (Deoxyribonucleic acid, or DNA) stored within a nucleus. Cells must perform many different functions to survive, including the synthesis of proteins, the removal of waste products, and the regulation of internal conditions or homeostasis. These functions require energy obtained from the chemical energy stored within molecules consumed by the cell as food (also called substrate).
An important function is cellular respiration, which is the conversion of the substrate molecule to usable energy, a crucial portion of the cell’s metabolism. The basic reaction for cellular respiration is the conversion of the simple carbohydrate glucose (C_6H_12O_6) into carbon dioxide and water by reacting it with oxygen, and in the process releasing its chemical energy used generate the cell’s energy storage molecule Adenosine Triphosphate (ATP) as see in equation (1).
