AP Bio - Ch.7: Cellular Respiration and Fermentation

Glucose

Gets oxidized to carbon dioxide in cellular respiration

Oxygen

Gets reduced to water in cellular respiration

Anaerobic Respiration

Catabolic pathway without the consumption of oxygen

• utilized by bacteria and lower organisms

• occurs exclusively in the cytosol

• glycolysis (fermentation) and ETC (doesn’t have oxygen as final electron acceptor)

Aerobic Respiration

Most efficient catabolic pathway. Consumes oxygen

• synonymously referred to as “cellular respiration”

• involves both anaerobic (glycolysis) and aerobic processes (> pyruvate oxidation > Krebs cycle > ETC with oxygen as final electron acceptor)

Glycolysis

Occurs in the cytosol of the cell

Breaks down glucose into 2 pyruvate

Net: 2 ATP and 2 NADH produced

Citric Acid Cycle

Also known as Krebs cycle, occurs in the matrix of the mitochondria.

Converts 2 pyruvate into 2 acetyl CoA, which adds carbon to 2 oxaloacetate and creates 2 citrate → kickstarts cycle of redox reactions to restore the 2 oxaloacetate

Net: 2 ATP, 8 NADH, 2 FADH, 6 CO2

Oxidative Phosphorylation

Also known as the Electron Transport Chain, occurs in the inner membrane (cristae) of the mitochondria

Electrons from NADH and FADH get transferred across protein complexes of electron carriers (from least electronegative to most electronegative) → shuttles H+ into membrane

• creates H+ gradient

• promotes spontaneous movement thru ATP synthase

Net: 28 ATP (max.) generated

fermentation

Anaerobic respiration involving (only) the extension glycolysis. Done through replenishing NAD+ concentrations. Occurs in the cytosol

Alcohol fermentation

Fermentation that produces acetaldehyde to turn NADH into NAD+

After accepting electrons from NADH, turns into ethanol (alcohol)

Lactate fermentation

Fermentation that produces lactate to turn NADH into NAD+. Occurs in humans