Alcohol FermentationProcess utilized by yeast to produce ATP in the absence of oxygen (anaerobic)• glycolysis (Starts with Glycoloysis)

– 2 ATP – 2 NADH – 2 pyruvate

• oxidized to produce 2 CO2 molecules• NADH oxidized to produce 2 NAD+ (regenerated)• Ethanol is the final product

Lactic Acid FermentationProcess utilized by animals to produce ATP in the absence of oxygen (anaerobic)– glycolysis

• 2 ATP • 2 NADH • 2 pyruvate

– NADH oxidizes to produce 2 NAD+ (regenerated)• end product is Lactate (ionized form of lactic acid) • performed in our muscles when oxygen is scarce (anaerobic)

Kreb Cycle

• The Kreb cycle, also known as the Citric Acid Cycle, begins in the mitochondria as the 2 molecules of pyruvate enter through active transport are further broken down to yield the remaining energy stored in the bonds.

Acetyl CoA• Before the cycle can begin the pyruvate molecules must be

converted to Acetyl CoA.– Pyruvate's -COO- (carboxyl group) is removed producing the 1st

molecule of CO2

– Acetate (CH3CO-) a 2 carbon compound is produced. – Coenzyme A (from a B vitamin) is added to the molecule via an

unstable -S- bond

• 2 molecules of CO2 are produced (1 each) • 2 molecules NADH are produced (1 each) which are later used in

the citric acid cycle

Citric Acid Cycle• 8 steps make up the citric acid cycle in which the

energy in the final 2 carbons are extracted.– Acetyl CoA (2-C)is attached to an Oxaloacetate

a (4-C) molecule • CoA is released. • Citric acid (6-C) is formed in the first step

– CO2 is produced • 5-C molecule

– NAD+ is reduced to NADH as an e- is harvested. – CO2 is produced

• 4-C molecule– NAD+ is reduced to NADH as an e- is harvested.

• Pi is added to ADP forming ATP

– 2 H+ are transferred to FAD to form FADH2 • energy carrying molecule like NADH

– Oxaloacetate is reformed and is ready to cycle again

– NAD+ is reduced to NADH as an e- is harvested

Summary

• Citric Acid Cycle – changes pyruvate into Acetyl CoA then

to citrate • 2 CO2

• 2 NADH

– cycles ultimately modifying citrate into the beginning molecule Oxaloacetate • 6 NADH • 2 FADH2

• 4 CO2 • 2ATP