Download S6. Using Yeast to Make Scientists-Introduction to

Saccharomyces cerevisiae is Brewer’s
Yeast
This is the same yeast that is used to leaven bread and ferment alcohol in
beer and wine
http://www.cosmopolitan.com/health-fitness/news/a35091/
Saccharomyces cerevisiae is a Model
Organism
Model organisms are used to study biological processes, with the hopes
of extrapolating results to humans. They are less expensive to maintain,
reproduce faster, and raise fewer ethical questions.
https://biology.uiowa.edu/model-organisms
Yeast are Eukaryotic
Yeast is a fungus. This makes it more closely related to humans than to
bacteria, which are prokaryotic.
https://commons.wikimedia.org/wiki/File:Tree_of_Living_Organisms_2.png
But…yeast?!
Yeast, unlike humans, is unicellular. But, like human cells, yeast:
•Has linear chromosomes
•Must respirate
•Must consume food
•Must sense the environment surrounding its cells
•Must arrest its growth in response to internal and environmental cues
http://mycor.nancy.inra.fr/blogGenomes/wp-content/uploads/2010/05/wheals21.gif
Yeast Can Grow on Liquid or Solid
Media
Yeast growth medium (YPD) includes proteins, yeast extract, and
glucose. YPD solid media also includes agar.
https://bmcresnotes.biomedcentral.com/articles/10.1186/1756-0500-4-74
https://sciencebrewer.files.wordpress.com/2012/04/dsc_0357.jpg
Yeast Reproduce by Budding
Look for budding today
Yeast reproduce asexually by budding, but can reproduce sexually if the
opportunity arises.
http://book.bionumbers.org/how-big-is-a-budding-yeast-cell/
Today’s Experiment
Methylene Blue Viability Assay
Our way to testing viability in your
projects
Methylene Blue Viability Assay
• Unlike Trypan Blue, all cells take up Methylene
Blue
• However, living cells reduce Methylene Blue
making it colorless
– How? Living cells undergoing glycolysis produce
NADH, which reduces Methylene Blue
NADH
Dead Cell
Methylene
Blue
Oxidized
Dead
Reduced
Alive
Living Cell
braukaiser.com