Cellular Respiration

1
Cellular Respiration

• An Overview

2
Principles of Energy Harvest

• Catabolic pathway v
  Fermentation vCellular
  Respiration
• C6H12O6 6O2 ---gt 6CO2 6H2O E (ATP heat)

3
Redox reactions

• Oxidation-reduction
• LEO the lion says GER
• Lose Electrons, OXIDATION
• Gain Electrons, REDUCTION
• Reducing agent e- donor
• Oxidizing agent e- acceptor

4
Oxidizing Agent in Respiration

• NAD (nicotinamide adenine dinucleotide)
• Removes electrons from food (series of reactions)
• NAD is reduced to NADH
• Enzyme action Dehydrogenase
• Oxygen is the eventual e- acceptor

5
Electron Transport Chain

• Electron carrier molecules found in membrane
  proteins
• Shuttle electrons that release energy used to
  make ATP
• Sequence of reactions needed to prevent energy
  release in 1 explosive step
• Electron route food---gt NADH ---gt electron
  transport chain ---gt oxygen

6
Cellular respiration

• Glycolysis happens in cytosol degrades glucose
  into pyruvate
• Krebs Cycle happens in mitochondrial matrix
  pyruvate changes form with a release of carbon
  dioxide
• Electron Transport Chain happens at inner
  membrane of mitochondrion electrons eventually
  passed to oxygen

7
Glycolysis

• 1 Glucose ---gt 2 pyruvate Energy investment
  phase cell uses 2 ATP to phosphorylate glucose
• Energy payoff phase 4 ATP are produced by
  substrate-level phosphorylation and NAD is
  reduced to NADH (x 2)
• Net energy yield per glucose molecule 2 ATP
  plus 2 NADH no CO2 is released occurs
  aerobically or anaerobically

8
Krebs Cycle

• If oxygen is present.
• Each pyruvate is changed to acetyl CoA CO2 is
  released
• NAD ---gt NADH coenzyme A (from vitamin B),
  makes molecule very reactive
• From this point each turn of cycle, 2 C atoms
  enter (acetyl CoA) and 2 exit (CO2)
• acetyl CoA (2 Cs) joins with oxaloacetate (4
  Cs)
• For each pyruvate that enters 3 NAD reduced to
  NADH 1 FAD2 reduced to FADH2 (riboflavin, B
  vitamin) 1 ATP made

9
Electron transport chain

• Cytochromes carry electron carrier molecules
  (NADH FADH2) down to oxygen
• Chemiosmosis energy coupling mechanism works
  using diffusion gradient
• ATP synthase produces ATP by using the H
  gradient pumped into the inner membrane space
  from the electron transport chain this enzyme
  harnesses the flow of H back into the matrix to
  phosphorylate ADP to ATP (oxidative
  phosphorylation)

10
Review Cellular Respiration

• Glycolysis
• 2 ATP (substrate-level phosphorylation)
• Acetyl CoA formation 2 ATP
  (substrate-level phosphorylation)
• Electron transport oxidative phosphorylation
  2 NADH (glycolysis) 4ATP
  2 NADH (acetyl CoA) 6ATP 6 NADH
  (Krebs) 18 ATP 2 FADH2 (Krebs) 4
  ATP
• 36 NET TOTAL ATP/glucose
  
  

11
Related metabolic processes

• Fermentation
• alcohol pyruvate to ethanol lactic acid
  pyruvate to lactate
• Facultative anaerobes (yeast/bacteria)
• Beta-oxidation lipid catabolism