Fermentation 101Fermentation 101

Ms. LevensailorMs. Levensailor

Cellular Respiration ReviewCellular Respiration Review

Oxidation: refers to the loss of electrons to Oxidation: refers to the loss of electrons to any electron acceptor (not just oxygen).any electron acceptor (not just oxygen).

For example: GlycolysisFor example: Glycolysis Oxidizes glucose to 2 molecules of pyruvate.Oxidizes glucose to 2 molecules of pyruvate. Oxidizing agent of glycolysis is NADOxidizing agent of glycolysis is NAD++ (not (not

oxygen).oxygen). Energy made is 2 ATPs (net) by substrate Energy made is 2 ATPs (net) by substrate

phosphorylation.phosphorylation.

Cellular Respiration ReviewCellular Respiration Review

If oxygen is present . . .If oxygen is present . . . Additional ATP is made by oxidative Additional ATP is made by oxidative

phosphorylation.phosphorylation.

HOWEVER, Glycolysis generates 2 ATPs HOWEVER, Glycolysis generates 2 ATPs whether oxygen is present or not!whether oxygen is present or not!

Anaerobic CatabolismAnaerobic Catabolism

Fermentation = anaerobic catabolism of Fermentation = anaerobic catabolism of organic nutrients.organic nutrients. Extension of glycolysis that can generate ATP Extension of glycolysis that can generate ATP

using only substrate-level phosphorylation.using only substrate-level phosphorylation. Requires sufficient supply of NADRequires sufficient supply of NAD++ to accept to accept

electrons during oxidation step of glycolysis.electrons during oxidation step of glycolysis. Without a mechanism to recycle NAD Without a mechanism to recycle NAD ++ from from

NADH, glycolysis would deplete the cell’s pool NADH, glycolysis would deplete the cell’s pool of NAD of NAD ++..

Anaerobic CatabolismAnaerobic Catabolism

How is NADHow is NAD++ recycled in aerobic recycled in aerobic conditions?conditions?The anaerobic alternative is to transfer The anaerobic alternative is to transfer electrons from NADH to pyruvate.electrons from NADH to pyruvate.There are many types of fermentation, There are many types of fermentation, differing in the waste products formed from differing in the waste products formed from pyruvate.pyruvate. Alcohol fermentationAlcohol fermentation Lactic Acid fermentationLactic Acid fermentation

Alcohol FermentationAlcohol Fermentation

Pyruvate is converted to ethanol (ethyl Pyruvate is converted to ethanol (ethyl alcohol) in 2 steps.alcohol) in 2 steps. 1. carbon dioxide is released from pyruvate, 1. carbon dioxide is released from pyruvate,

which is converted to acetaldehyde.which is converted to acetaldehyde. 2. acetaldehyde is reduced by NADH to 2. acetaldehyde is reduced by NADH to

ethanol.ethanol.Regenerating a a supply of NADRegenerating a a supply of NAD++

Alcohol fermentation by yeast (a fungus) is Alcohol fermentation by yeast (a fungus) is used in brewing & winemaking.used in brewing & winemaking.

Alcohol FermentationAlcohol Fermentation

Lactic Acid FermentationLactic Acid Fermentation

Pyruvate is reduced directly by NADH to form Pyruvate is reduced directly by NADH to form lactate (no release of COlactate (no release of CO22).).

Lactic acid fermentation by certain fungi and Lactic acid fermentation by certain fungi and bacteria are used in the dairy industry to make:bacteria are used in the dairy industry to make: CheeseCheese YogurtYogurt

Human muscles make ATP by lactic acid Human muscles make ATP by lactic acid fermentation.fermentation. Sugar catabolism for ATP production outpaces the Sugar catabolism for ATP production outpaces the

muscle’s supply of oxygen from the blood.muscle’s supply of oxygen from the blood.

Lactic Acid FermentationLactic Acid Fermentation

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In your composition book:In your composition book: Make a Venn Diagram Make a Venn Diagram Compare and contrast Fermentation & Compare and contrast Fermentation &

Cellular RespirationCellular Respiration

Fermentation Cellular Respiration