Lecture on Cellular Respiration and ATP Production

Overview

• The lecture discusses three pathways for producing 36 ATPs.
• Emphasis on pathways involving glycolysis, Krebs cycle, and electron transport chain.

Glycolysis

• Purpose: Produce ATP without oxygen and mitochondria.
• Process:
  • Glucose is oxidized to pyruvic acid.
  • Involves loss of two pairs of hydrogens (each hydrogen has 1 proton and 1 electron).
  • NAD acts as a carrier (taxicab) for hydrogens, becoming NADH.
  • Produces pyruvic acid and ATP through substrate-level phosphorylation.
  • Net ATP Gain: 2 ATPs (4 produced, 2 used).
  • Without oxygen, pyruvic acid converts to lactic acid.

Krebs Cycle (Citric Acid Cycle)

• Start: Pyruvic acid enters mitochondria.
• Conversion: Pyruvic acid transformed by coenzyme A (CO2 released, acetyl-CoA formed).
• Products per cycle:
  • CO2 (exhaled via respiratory system).
  • 1 ATP.
  • Multiple NADH and FADH2 (hydrogen carriers).
  • Each glucose molecule results in two turns of the cycle (2 ATPs total).

Electron Transport Chain

• Location: Inner mitochondrial membrane.
• Process:
  • NADH and FADH2 transfer electrons to proteins in the chain.
  • Electrons facilitate proton pumping across the membrane, creating a gradient.
  • ATP is synthesized by ATP synthase as protons flow back across the membrane.
  • ATP Yield: 3 ATPs per NADH due to proton gradient.
  • Total ATP production from NADH in citric acid cycle is significant (24 ATPs from NADH alone).

Summary of ATP Production

• Glycolysis: 2 ATPs.
• Krebs Cycle: 2 ATPs.
• Electron Transport Chain: Majority of ATPs, using NADH and FADH2.
• Total: Conceptually reaching 36 ATPs per glucose molecule.

Additional Notes

• The lecture references a video to further explain the electron transport chain.
• Key takeaway: Efficiency of cellular respiration processes in generating energy.

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This summary outlines the processes and key components of cellular respiration, essential for understanding ATP production in biological systems.