David Snow
Glycolysis
Krebs Cycle
1. Occurs in the Cytosol
2. Glucose is split into 2 pyruvate molecules
1. Occurs in mitochondrial matrix
2. 1. Pyruvate is converted into Acetyl CoA
as it enters mitochondria
3. Acetyl CoA converted to CO2
4. ATP synthesized by substrate-level
phosphorylation (1 per pyruvate)
5. Requires molecular oxygen to proceed*
3. ATP synthesized by substrate-level
phosphorylation (2 per glucose)
4. 2 phases:
 energy investment – cell spends ATP
to phosphorylate fuel molecules
 energy pay-off phase – ATP produced
and NAD+ reduced to NADH
5. net energy yield is 2 ATP and 2 NADH
per glucose molecule
6. no CO2 released in glycolysis. All carbons
are present in pyruvate molecules
7. Can occur whether or not molecular
oxygen is present *
6. Completes the oxidation of glucose
7. CO2 is the exhaust
8. Most energy of the cycle is carried by
NADH
9. For each acetate, 3 NAD+ are reduced to
NADH
10. In one turn of cycle, electrons are given to
1 FAD to make 1 FADH2
Oxidative Phosphorylation: Electron Transport
Chain
1. occurs in inner-membrane of mitochondria
2. accepts electrons from other stages,
typically in the form of NADH
3. ATP synthesized by oxidative
phosphorylation
4. Electrons are passed down the chain, to
ever-increasing electronegative molecules,
with energy being created at each step in
chain. At end of chain, electrons are
combined with Oxygen (very
electronegative) to form water
5. Creates almost 90% of all ATP produced
in cell respiration (32 per glucose)
6. Requires molecular oxygen to proceed*
7. Most components of chain are proteins
8. FADH2 and NADH reduce the chain,
driven by electrons
9. For every 2 NADH, one oxygen molecule
is reduced to 2 molecules of water
10. for every NADH, enough energy is given
to proton-motive force to produce 2.5-3
ATP. FADH2 yields 1.5-2 ATP in similar
reaction.
* - Without oxygen, NAD+ cannot be regenerated. i.e. Krebs Cycle and Electron Transport Chain will not function