Yeast are single-celled microorganisms, meaning individual yeast are made up of only one cell. To compare, all animals and most plants are multicellular organisms. Yeast are microorganisms! On this scale , you can see just how small a yeast cell is in comparison to plant and animal cells. Yeast cells are so small, that you need a microscope to see them. Yeast are eukaryotic cells, They are different from meaning they have a defined nucleus and bacterial cells, which are membrane-bound prokaryotic and therefore organelles. do not have a defined nucleus or organelles. Yeast are classified as part of the Fungi Kingdom, separate from the Plant and Animal Kingdoms. There are hundreds of yeast species, but usually when people talk about yeast, they are talking about Saccharomyces cerevisiae, the species commonly used in baking. If you did our yeast experiments, you already know that when yeast respire, they release carbon dioxide gas. This is a process known as cellular Glucose respiration: a carbon source, like glucose, is converted into energy, a molecule called ATP. Pyruvate
Anaerobic respiration Aerobic respiration (fermentation)
ATP, ATP, H20, ethanol, CO2 CO2 Aerobic respiration is a metabolic process that occurs in the presence of oxygen and turns nutrients into energy. This is a process that both single-celled and multicellular organisms perform.
The release of carbon dioxide by the yeast is what causes the tiny bubbles in bread dough, making it rise and giving it an airy texture. In the balloon experiment, the yeast are performing anaerobic respiration, or fermentation, because their environment is lacking oxygen.
This is the same process that is used to make beer.
Yeast are invaluable to the scientific community because they are used as model organisms for eukaryotes. In the lab, they have been used to generate biopharmaceuticals, such as the hepatitis vaccine and insulin to treat diabetes. • http://www.aboutthemcat.org/biology/prokar yotic-vs-eukaryotic-cells.php • http://blog.beeriety.com/2009/07/06/how- beer-is-made/ • https://www.ncbi.nlm.nih.gov/pmc/articles/P MC3728191/ • http://www.trackingvaccinations.com/