Concept 9.5: Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen

Flashcards from Concept 9.5 of Pearson's Campbell Biology, Twelfth Edition.

Aerobic respiration

The most common type of cellular respiration that involves the use of oxygen to pull electrons down the electron transport chain

Anaerobic respiration

Respiration wihtout oxygen that uses an electron transport chain with an electron acceptor other than oxygen

• Sulfate ions may serve the role of acceptor in some organisms, making H₂S instead

Glycolysis

Process that oxidizes glucose to pyruvate without the involvement of O₂ or an electron transport chain

• Produces 2 net ATP by substate-level phosphorylation regardless of O₂ presence

• Most widespread catabolic pathway on Earth that functions in both fermentation and cellular respiration

NAD⁺

The oxidizing agent that accepts electrons during glycolysis

• Regenerated from NADH by transferring electrons to the electron transport chain under aerobic conditions

• Anaerobic conditions require fermentation to regenerate this

Fermentation

An extension of glycolysis that oxidizes NADH by transferring electrons to pyruvate or its derivatives, includes:

• Alcohol fermentation

• Lactic acid fermentation

Differs from cellular respiration as electrons are not transferred to the electron transport chain and does not produce nearly as much ATP

Alcohol fermentation

The conversion of pyruvate to ethanol by:

• Releasing CO₂ from pyruvate

• Producing NAD⁺ and ethanol

Used in brewing, winemaking, and baking

Lactic acid fermentation

The reduction of pyruvate directly by NADH to form lactate and NAD⁺

• Does not release CO₂

• Used to make cheese and yogurt with fungi and bacteria

Lactate

A substance that was thought to only have been produced by human muscle cells with a lack of oxygen

• Actually is produced even under aerobic conditions, thus disqualifying it from being classified as fermentation