Cellular Respiration Processes Quiz

Fermentation and Cellular Respiration

• Fermentation recycles NADH back to NAD+ to maintain glycolysis.
• Fermentation is involved in the catabolism of glucose to produce ATP.

Alternate Substrates for Cellular Respiration

• Amino acids can be converted into glucose, acetyl-CoA, or citric acid cycle intermediates after deamination.
• Triglycerides can be split into glycogen and fatty acids, which can be converted into acetyl-CoA, NADH, and FADH2 through beta-oxidation.

Cellular Respiration Overview

• Cellular respiration is the process of breaking down glucose to produce ATP using substrate-level and oxidative phosphorylation.
• The three stages of cellular respiration are glycolysis, pyruvate oxidation, and the citric acid cycle, followed by oxidative phosphorylation.

Glycolysis

• Glycolysis is the first stage of cellular respiration, using glucose as its preferred substrate.
• Glycolysis produces 2 ATP (net, via substrate-level phosphorylation), 2 NADH, and 2 pyruvate.
• Contrast the investment and payoff phases in glycolysis.

Pyruvate Oxidation and Citric Acid Cycle

• The two pyruvates from glycolysis are imported into the mitochondria via pyruvate oxidation, producing 2 acetyl-CoA, 2 NADH, and 2 CO2.
• The 2 acetyl-CoA enter the citric acid cycle, producing 2 ATP (via substrate-level phosphorylation), 6 NADH, and 2 FADH2.

Oxidative Phosphorylation

• In the mitochondrial matrix, NADH and FADH2 from glycolysis, pyruvate oxidation, and the citric acid cycle donate high-energy electrons to the mitochondrial electron transport chain (ETC).
• The ETC uses the energy to pump H+ into the intermembrane space, generating proton motive force (PMF) across the inner membrane.
• The flow of hydrogen ions back across the inner membrane powers the production of ATP by the enzyme complex ATP synthase through chemiosmosis.
• Oxidative phosphorylation is the process of generating ATP through the ETC coupled to chemiosmosis in the mitochondria.

Electron Transport Chain and ATP Synthesis

• The electron transport chain is the process of transferring electrons from high-energy donors to oxygen, generating PMF.
• The components required for oxidative phosphorylation in the three compartments around the mitochondrial inner membrane are:
  • Inner membrane: electron transport chain and ATP synthase
  • Intermembrane space: hydrogen ions
  • Mitochondrial matrix: NADH, FADH2, and ATP synthase
• The role of each component in the process is:
  • Electron transport chain: generates PMF
  • ATP synthase: produces ATP through chemiosmosis
  • Hydrogen ions: drive ATP synthesis through chemiosmosis

Test your knowledge on the process of cellular respiration, including glycolysis, pyruvate oxidation, and ATP production through substrate level and oxidative phosphorylation.