Ethanol Concentration On Fermentation Of Saccharomyces Cerevisiae

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TITLE
The Effect of Varying Ethanol Concentrations on Fermentation of Saccharomyces Cerevisiae
INTRODUCTION
I will be studying varying concentrations of ethanol and their effect on fermentation of saccharomyces cerevisiae, which is a yeast commonly known as brewer’s yeast. The first step of alcohol fermentation begins with glycolysis, which is the process of breaking down glucose molecules, the breakdown of glucose through glycolysis forms two pyruvate molecules, and two carbon dioxide molecules. The final steps of fermentation are anaerobic, occurring without oxygen. Pyruvate is split into carbon dioxide and two carbon acetaldehydes. Then electrons and hydrogen are transferred from NADH to the acetaldehyde, then 2 NAD+ and EtOH are formed. NAD+ is regenerated to continue glycolysis, but no additional ATP is produced. The final net products of fermentation are two ATP from glycolysis, 2 CO2, and two EtOH molecules per glucose (Starr et. al. 2016). The chemical formula for fermentation is C6H12O  C2 H5 OH + CO2. Yeast cells are able to …show more content…

Ethanol becomes an inhibitor of fermentation which begins to occur at very low concentrations of ethanol, often less than 3% vol/vol. High levels of ethanol cause cells to begin to leak, which leads to magnesium loss. When magnesium beings to leak out of the cell, the cell no longer is able to perform glycolysis which stops fermentation (Ma and Liu, 2010). At high concentrations ethanol has been shown to disrupt the shape of protein causing protein denaturation and dysfunction. Pyruvate, an enzyme that is generated through glycolysis is denatured by high concentrations of ethanol which inhibits fermentation from occurring (Ma and Liu, 2010). Finally, high ethanol levels also affect the uptake of glucose, which stops glycolysis from occurring and inhibits fermentation (Ma and Liu,

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