1. Learning Goal: I will be able to explain the difference between aerobic and anaerobic respiration, as well as the two types fermentation: lactic acid fermentation and alcoholic/ethanol fermentation (including when/where each are performed, and the benefits/disadvantages of each)

2. If no oxygen is available, cells can obtain energy through the process of anaerobic respiration.
What is the purpose of Anaerobic Respiration?
Glycolysis occurs, so both ATP and NADH are produced
The problem occurs in the ETC because there is no oxygen to be the final electron acceptor
NADH builds up in the system, and NAD+ cannot be regenerated normally
Fermentation allows the production of a small amount of ATP without oxygen

3. There are two primary fermentation processes:
Lactic Acid Fermentation
Alcohol Fermentation
Lactic acid fermentation occurs when oxygen is not available in muscle cells (see Fig. 4, p. 120)
For example, in muscle tissues during rapid and vigorous exercise, muscle cells may be depleted of oxygen. They then switch from respiration to fermentation.

4. Glucose → 2Pyruvic acid → 2Lactic acid + 2NAD+ + 2ATP
The pyruvate formed during glycolysis is broken down to lactic acid (pyruvate rxts with NADH to reoxidize it to NAD+ to allow glycolysis to continue)
Glucose → 2Pyruvic acid → 2Lactic acid + 2NAD+ + 2ATP
The process of lactic acid fermentation replaces the process of aerobic respiration so that the cell can have a continual source of energy (NAD+ to make more ATP through glycolysis), even in the absence of oxygen.
However this shift is only temporary and cells need oxygen for sustained activity.

5. Lactic acid that builds up in the tissue causes a burning, painful sensation.
Most lactic acid made in the muscles diffuse into the bloodstream, then to the liver, where it is converted back to pyruvate when oxygen becomes available

6. Alcohol (ethanol) fermentation occurs in yeasts and some bacteria
Alcohol (ethanol) fermentation occurs in yeasts and some bacteria. (see Fig. 2, p. 119)
Pyruvate formed during glycolysis is broken down to produce ethanol and carbon dioxide and is released (and this causes NADH to be reduced to NAD+ so that it can continue through the process of glycolysis to form 2 more ATP)

7. Glucose → Pyruvic acid → alcohol + carbon dioxide + energy

8. Fermentation is used in food production.
Yogurt - Soy Sauce
Cheese - Vinegar
Bread - Olives/Pickles
Beer/ Meade - Wine/ Ale
Sauerkraut - Malt

9. Alternative Metabolic Pathways
Glucose is not the only nutrient that is required for the successful production of ATP through aerobic respiration.
Protein Catabolism
Proteins from your diet are broken down into amino acids which are then used by the individual cells in your body.
First, amino acids are de-aminated (the removal of the amino group of the amino acid to form ammonia NH3

10. The remaining portions of the amino acid are used as various components in both glycolysis and the Kreb’s cycle
For example:
1) Leucine is a component of acetyl CoA
2) Alanine is converted into pyruvate

11. Protein Catabolism
Protein Hydrolysis Amino acids
Deamination ammonia (NH3)
Urine
Kreb’s Cycle
Glycolysis

12. Lipid Catabolism
Fats are broken down into their simple components of glycerol and 3 fatty acids.
The glycerol portion may be converted into glucose or converted into 3-phosphoglycerate (G3P)
Fatty acids are transported into the matrix of the mitochondria and are converted into acetyl CoA by a process called β-oxidation which is then used in the Krebs cycle

13. Glycerol G3P Glucose Lipid Catabolism
Lipid (Triglyceride) hydrolysis 3 fatty acids β-oxidation acetyl CoA (2C) Kreb’s Cycle
Glycerol
G3P
Gluconeogensesis
Glucose
GLYCOLYSIS

14. How Did We Do? I will be able to explain the difference between aerobic and anaerobic respiration, as well as the two types fermentation: lactic acid fermentation and alcoholic/ethanol fermentation (including when/where each are performed, and the benefits/disadvantages of each)