Lecture Notes: Cellular Respiration and Introduction to Photosynthesis

Announcements

• Monday: Fourth quiz on Chapters 6 and 7
  • 2 questions from Chapter 6, 8 questions from Chapter 7
• Wednesday: Second exam covering Chapters 5-8
  • Study guide uploaded
  • Discussion board available for questions

Cellular Respiration (Chapter 7)

Citric Acid Cycle

• Occurs in the mitochondria after glycolysis
• Key Takeaway: Acetyl-CoA enters the cycle, releasing:
  • 2 CO2 molecules
  • Reduces 3 NAD+ to 3 NADH
  • Reduces 1 FAD to FADH2
  • Produces 1 ATP
• Cycle regenerates oxaloacetate
• Overall Glucose Yield:
  • 6 CO2, 4 ATP, 10 NADH, 2 FADH2

Electron Transport Chain

• Located in the inner mitochondrial membrane
• NADH and FADH2 donate electrons to protein complexes
  • Proton pumping into intermembrane space
• Oxygen is the final electron acceptor (aerobic respiration)
  • Produces water
• Proton gradient drives ATP synthase
  • ATP production through chemiosmosis

Photosynthesis Overview

Historical Context

• Early belief: Plants grow by absorbing nutrients from soil
• Discovery: Carbon dioxide from air contributes to biomass

Photosynthesis Process

• Converts light energy to chemical energy (glucose)
• Oxygen is a byproduct
• Occurs in chloroplasts (in leaf mesophyll cells)
  • Thylakoid membranes contain chlorophyll

Types of Photosynthesis

• Oxygenic (produces oxygen)
• Anoxygenic (does not produce oxygen)

Photosynthesis Reaction

• 6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
• Anabolic process (requires energy input)

Stages of Photosynthesis

1. Light-dependent Reactions
   • Occur in thylakoid membranes
   • Produce ATP and NADPH, release O2
2. Calvin Cycle (Light-independent Reactions)
   • Occur in stroma
   • Use ATP and NADPH to convert CO2 into glucose

Importance

• Photosynthesis is vital for oxygen production and energy for life

Next Steps

• Monday: Quiz on Chapters 6 and 7
• Continue with Photosynthesis