1. How Cells Make ATP
Chapter 7

2. Cellular Respiration Aerobic respiration: Anaerobic respiration
Releases the energy in glucose in a steady fashion
Requires molecular oxygen
Includes redox reactions
Anaerobic respiration
Anaerobic respiration and fermentation
Does not require oxygen
All exergonic

3. Aerobic respiration Four stages: Glycolysis – in the cytosol
Formation of acetyl CoA
Citric acid cycle in mitochondria
Electron transport/chemiosmosis

4. Figure 7-2 p. 139

5. Glycolysis ‘sugar splitting’ Does not require oxygen Two major phases:
Energy investment phase (endergonic)
Energy capture phase (exergonic)
Each glucose molecule is converted to 2 pyruvate molecules and 2 NADH and 2 ATP

6. Formation of acetyl CoA
Pyruvate molecules (from glycolysis):
1st carboxyl group is split off as CO2
Remaining 2-carbon fragment is oxidized and e- transferred to NAD+
The oxidized 2-carbon fragment is attached to coenzyme A  acetyl CoA

7. Citric acid cycle (aka Krebs Cycle):
For every glucose molecule from glycolysis, 2 acetyl groups enter
Each 2-C acetyl group combines with a 4-C compound
2 CO2 molecules are removed from each
1 ATP, 3 NADH, 1 FADH2 per acetyl group – the energy here will be use to synthesize more ATP in the next phase

8. Figure 7-6 p. 144

9. Electron transport chain
A series of electron carriers in the mitochondrial membrane
Electrons pass down in a series of redox reactions
e- lose energy as they pass along the chain
This energy allows the cell to move H+ to the intermembrane space and create a proton gradient (chemiosmosis)
The H+ protons can only move back into the matrix through ATP synthase  this provides the energy for converting ADP + Pi to ATP

10. Figure 7-9 p. 148

11. Figure 7-10 p. 149

12. Electron transport and chemiosmosis oxidative phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
Glycolysis
Glucose
ATP 2
NADH
4 – 6
ATP
Figure 7-11 Page 150
Pyruvate
Acetyl coenzyme A 2
NADH 6
ATP 6
NADH 18
ATP
Citric acid cycle
ATP 2
FADH2 4
ATP
Electron transport and chemiosmosis
ATP
Total ATP from
oxidative phosphorylation

13. Alternative pathways
Many organisms depend on nutrients other than glucose
Products of protein and lipid catabolism enter the same pathways as glucose

14. Anaerobic respiration
Electrons transferred from fuel molecules to the electron transport chain
The final electron acceptor is an inorganic substance such as nitrate (for the nitrogen cycle) or sulfate

15. Fermentation Also anaerobic
But does not use an electron transport chain
Electrons are transferred to an organic molecule
This process produces either alcohol or lactate