Download Fermentation/ Citric Acid Cycle

Fermentation and YOU!!!
Lactic Acid Fermentation- Think about how your body is responding when you exercise
- Muscles are working hard (USING ATP)
- You are breathing heavy (NOT GETTING ENOUGH OXYGEN)
These are prefect conditions for FERMENTATION
- After a hard workout, why are your muscles sore?
o Answer: Lactic acid has built up in the CYTOSOL
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Alcoholic FermentationThis process is the basis of the beer and wine industry
Yeast cells are added to a fermentation mixture, and ethyl alcohol accumulates
Baking bread also depends on this type of fermentation
Aerobic Respiration:
- Anaerobic respiration is sufficient for most small, unicellular organisms
- However, for organisms with higher energy requirements (like US), the low efficiency of
glycolysis is not sufficient
o Remember: after glycolysis, the cell must make a decision about what to do next
- When OXYGEN is PRESENT in the cell, it chooses to carry out AEROBIC RESPIRATION
2 Main Steps
- The KREBS (CITRIC ACID) CYCLE
o Occurs in the matrix of the mitochondrion
- Electron Transport Chain
o Occurs on the inner membrane of the mitochondrion
The KREBS CYCLE:
- Pyruvic acid diffuses from the cytosol into the MATRIX of the Mitochondria
- It is then CONVERTED into a 2- Carbon molecule called ACETYL CoA in a simple reaction
that CREATES and RELEASES CO2
The history of the KREBS CYCLE:
- Discovered by Hans Krebs, who is a German biochemist (1900-1981)
- Sometimes it is also called the citric acid cycle
THE KREBS CYCLE:
Output:
- 1 molecule of ACETYLE CoA is broken down by each turn of the cycle
- Therefore, 1 glucose molecule causes 2 cycles
There for, one molecule of glucose yields (produces)
 6 molecules of NADH
 2 Molecules of FADH2
 2 Molecules of ATP
 4 molecules of CO2
These molecules will be utilized will be utilized in the next (and final) step of respiration:
THE ELECTRON TRANSPORT CHAIN
The Electron Transport Chain:
- Occurs on the inner mitochondrial membrane
- NADH and FADH2 contain high energy electrons that are passed along a transport chain
(similar to the chain in the light reactions of photosynthesis)
- The energy they released is used to PUMP PROTONS out of the MATRIX
- CHEMIOSMOSIS: protons diffuse back into the matrix through the enzyme ATP synthase
- Oxygen’s role = final electron acceptor
- As electrons leave the transport chain, they are combined with oxygen and protons in
order to form water……
o O2 + 4e- + 4H+  2 H2O
Energy Scorekeeping:
- GYCOLYSIS and ANAEROBIC Respiration
o Yields 2 ATP Per  1 Glucose Molecule
o 3.5% Efficiency
- Glycolysis and Aerobic Respiration
o Yields a total of 38 ATP per 1 Glucose molecule
o 66% efficiency