THE EXPERIMENT: yeast cells without blue stain: nothing is stainedall is clear y
ID: 4072 • Letter: T
Question
THE EXPERIMENT:yeast cells without blue stain: nothing is stainedall is clear
yeast cells in blue dye: some (very few) yeastcells turn blue
boiled yest cells with blue dye: all cells turnblue
a.) what are the live cells doing to remain clear and unstained bythe dye?
b.) what does boiling probably do to the yeast(s) membrane (it doesnot break it- the cell content would spill out) that results in theboiled cell(s) blue appearance?
c.) in a preparation of unboiled yeast, a few blue yeast cells areusually noticed. What assumption can you make concerning these bluecells?
Explanation / Answer
The live yeast cells do not appears as blue color, because live cells produce an enzyme, which degrades blue color. Thus, they cannot appear as blue. (The methylene blue staining procedure is used to measure yeast viability based on the assumption that the methylene blue will enter the cells and be broken down by living yeast cells that produce the enzymes which breaks down methylene blue, leaving the cells colorless). The boiled yeast cell becomes dead; hence they cannot synthesize enzyme, which is required to degrade the dye. Thus, they appear as blue. (The non- viable cells do not produce this enzyme (or enzymes) and as such the methylene blue that enters the cells are undegraded causing the cells to remain colored (the oxidized form concentrates intracellularly).
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