1. C. FATE OF PYRUVATE 1. Why cell gets rid of pyruvate
a. the process of glycolysis causes cell to run out of NAD+ so glycolysis stops
b. all cells must do glycolysis all of the time,
therefore, they must use pyruvate to regenerate NAD+ for cell
c. there is a lot of energy trapped in pyruvate and ideally cells would access that energy, but that is only possible if a cell has a mitochondria and access to oxygen

2. FATE OF PYRUVATE
PYRUVATE
H2C-OH l
CH3
S-CoA l
C=O
CH3
COOH l
HCOH
CH3

3. OH l
C=O
CH3
bacteria
pyruvate
NADH + H+
NAD+
CO2
H2C-OH l
CH3
ethanol

4. animal muscle cells pyruvate O2 is present no O2 Lactic acid OH l C=O
CH3
animal muscle cells
pyruvate
O2 is present
no O2
NADH + H+
NAD+
NADH + H+
NAD+
COOH l
HCOH
CH3
Lactic acid

5. eukaryotic cells with O2OH l
C=O
CH3
pyruvate
NADH + H+
NAD+
CoASH
CO2
S-CoA l
C=O
CH3
acetyl-CoA
eukaryotic cells with O2

6. 2. What is coenzyme-A

7. a. coenzyme-A is a carrier that helps
a. coenzyme-A is a carrier that helps enzymes hold and modify molecules
b. coenzyme-A has a sulphur and hydrogen functional group [designated as – SH ]
c. the result is that we use the code CoASH for an unbonded coenzyme-A
and the code – CoA when coenzyme-A is attached to another molecule

8. 2. Three pathways for pyruvate
a. ethanol fermentation -occurs in bacteria or yeast cells
pyruvate + NADH + H ethanol + CO2 + NAD+

9. b. lactic acid fermentation. - occurs in animal cells in the
b. lactic acid fermentation - occurs in animal cells in the temporary absence of oxygen
pyruvate + NADH + H lactic acid NAD+

10. but they do both release NAD+ to allow the cell to continue glycolysis
both fermentation steps above do NOT directly create any high energy compounds
but they do both release NAD+ to allow the cell to continue glycolysis
c. oxidation of pyruvate - occurs in the mitochondria in the presence of oxygen
pyruvate + NAD CoA-SH acetyl-CoA + NADH + H CO2

11. acetyl-CoA has energy in it that can be used to make more high energy compounds by more processing