Lecture on Cellular Respiration and ATP Generation

Overview

• Previous discussion: Krebs Cycle
  • Generation of NADH and FADH2
• Current focus: How NADH and FADH2 generate ATP
• Introduction to Fermentation as an alternative energy pathway

Electron Transport Chain (ETC)

• Location:
  • Plasma membrane of bacteria
  • Inner mitochondrial membrane
• Function:
  • Transport electrons from NADH and FADH2
  • Electrons move down a chain of proteins
  • Energy levels decrease moving through chain, ending on oxygen
  • Oxygen: Ultimate electron acceptor, forms water

Role of ETC in ATP Production

• Electrons release energy as they travel
• Energy is used to produce ATP
• Energy from electron carriers (NADH, FADH2) is converted to ATP
• ETC visualized as steps, where NADH starts higher than FADH2

Energy Differences: NADH vs. FADH2

• NADH enters Complex I (higher energy state)
• FADH2 enters Complex II (lower energy state)
• ATP yield:
  • 1 NADH ≈ 3 ATP
  • 1 FADH2 ≈ 2 ATP

Proton Gradient Creation

• Energy from electrons pumps protons into extra-cytoplasmic space or mitochondria inner membrane space
• Gradient: High concentration of protons outside, low inside
• Proton gradient: Source of potential energy for ATP synthesis

ATP Synthesis via ATP Synthase

• ATP Synthase: Key enzyme allowing protons to move back across the membrane
• As protons move back, energy released is used to synthesize ATP from ADP
• ATP formation couples with proton movement
• ATP Synthase acts as a molecular motor

Importance of Oxygen

• Role in accepting electrons
• Absence of oxygen halts electron transport chain
• No gradient without oxygen = no ATP production
• Essential for respiration and cellular energy

Supplemental Animations

• Two animations provided for further understanding:
  • 1st Animation: Simple overview
  • 2nd Animation by Harvard: Detailed graphics, not for note-taking
• Encouragement to watch these for enhanced understanding

Closing

• Importance of these processes for cellular energy production
• Understanding enhances performance in assessments