1. SBI 4U: Metablic Processes
ANAEROBIC PATHWAYS
NAD+ is in limited supply, so if the cell does not have a way to oxidize the NADH back to NAD+ glycolysis will come to a halt.
The ETC oxidizes NADH to NAD+ when oxygen is present. Eukaryotic organisms have two primary means of oxidizing NADH when oxygen is not present. Bacteria have developed tons of methods.
These processes are called fermentation.
Glycolysis occurs and glucose is broken down into 2 pyruvate, 2 NADH + 2H+, and 2 ATP (net).
Then:
Section 1.3

2. ETHANOL FERMENTATION (yeast cells)
SBI 4U: Metablic Processes
ETHANOL FERMENTATION (yeast cells)
Pyruvate is immediately decarboxylated into acetylaldehyde (CH3COH)
NADH is then oxidized back into NAD+ and the protons (H+) turn acetylaldehyde into ethanol.
Still only a net of 2ATP.
Section 1.3

3. LACTATE FERMENTATION (animal cells)
SBI 4U: Metablic Processes
LACTATE FERMENTATION (animal cells)
Pyruvate is immediately reduced by NADH (NADH is oxidized into NAD+) to form lactate
Lactate (lactic acid) is thought to cause muscle pain and stiffness, but current research suggests it is just a correlation
Oxygen debt is the amount of oxygen required to catabolize lactate into carbon dioxide and water.
Lactic acid is transported to the liver and is oxidized back into pyruvate when the oxygen debt is repaid.
Section 1.3

4. SBI 4U: Metablic Processes
VO2 max
The maximum volume of oxygen that the cells of the body can remove from the bloodstream while the body experiences maximal exertion (mL/kg/min)
Measures the body's capacity to generate the energy required for physical activity
Higher VO2 values are associated with higher aerobic fitness (see Table 2 and 3, pg 122)
Average ~35 mL/kg/min, Elite athlete ~70 mL/kg/min
Lab Activity p. 131 Estimating VO2 max (a less intense, inexpensive way to estimate your VO2 max).
Section 1.3