1. FERMENTATION

2. Calling all NAD+ please!
Glycolysis allows organisms to obtain energy from nutrients in the absence of oxygen
Step 6 in the glycolytic pathway reduces NAD+ to NADH
However, cells possess a limited supply of NAD+
If glycolysis continues without a mechanism to oxidize NADH back to NAD+, step 6 would be blocked and glycolysis would STOP
In aerobic respiration, the ETC oxidized NADH allowing glycolysis to continue

3. Oh give me another way…
Organisms have several ways of recycling NAD+ and allowing glycolysis to continue when oxygen is not available
One method involves the transfer of the hydrogen atoms of NADH to certain organic molecules instead of the ETC
This process is known as fermentation

4. Fermentation Eukaryotes use 2 methods of fermentation
Ethanol fermentation
Lactic acid (lactate) fermentation

6. Ethanol Fermentation

7. Ethanol Fermentation: The Process
Some bacteria, yeast, mold, etc.
the pyruvate that is produced by glycolysis is decarboxylated to form acetaldehyde
Acetaldehyde is then used to oxidize NADH
Glucose + 2 ADP +2 Pi—-> 2ATP + 2CO2 +2 Ethanol

8. Ethanol Fermentation
The 2 ATP molecules produced in glycolysis satisfy the organisms energy needs and the ethanol and CO2 are released as waste products
Humans use these waste products to produce breads, pastries, wine, beer, liquor, etc.

9. Lactic Acid Fermentation

10. Lactic Acid Fermentation
During strenuous exercise, muscles respire glucose faster than oxygen can be supplied
Under these conditions, oxidative respiration slows down and lactic acid fermentation begins

11. Lactic Acid Fermentation: The Process
Glycolysis proceeds rapidly, yielding 2 ATP for every glucose
any excess pyruvate formed in cytosol is converted into lactate
pathway regenerates NAD+ which is used to maintain high rate of glycolysis
commonly occurs in the cytosol
glucose + 2 ADP +2Pi —-> 2 lactate + 2ATP

12. Lactate threshold and oxygen debt
during highly strenuous physical activity lactate produced is transported from muscles to liver
it is oxidized back to pyruvate so it does not build up
lactate threshold: point at which lactate production is too high from transport out of muscles.

13. is lactic acid to blame for muscle soreness???

14. Anaerobic respiration
what is a prokaryote?
What if oxygen can not be the final electron acceptor?
Organism without membrane bound organelles!!!
sulfate
nitrate
iron Fe
SO4-2
NO31-

15. Homework Section 4.4 p. 190-194 Chapter 4 practice questions
unit test review -OCT 24th