1. Fill in the table below. Energy cost is usually a number of ATP's or 0 for each reaction;
energy yield is usually a number of ATP's, a number of NADH's, or 0 for the reaction.
In the last column only , answer for 1 glucose molecule going through glycolysis.

2. Use either Figure 14-2 or a map you make of glycolysis. Write one sentence or phrase to describe what each enzyme does. You may use abbreviations as long as you can remember what each abbreviation means.

3. Classify each of the enzymes in glycolysis (oxidoreductase, transferase, hydrolase, ligase, lyase, isomerase). Which enzyme classes do not appear in glycolysis?

4. Draw a fructose molecule and add two phosphates to it, one at C1 and the other at C6. Draw a line through the middle of the molecule. Which glycolysis reactions have you just summarized?

5. The net energy yield from glycolysis depends partly on what happens to pyruvate and partly on the starting molecule.
a. What is the net energy yield from converting one glucose to two pyruvates?
b. What is the net energy yield from converting one glucose-6-P to two pyruvates?
c. What is the net energy yield from converting one fructose-6-P to two pyruvates?

6. Glyceraldehyde-phosphate dehydrogenase catalyzes a two-part reaction in glycolysis.
a. Write the two parts of the reaction. You do not need to draw any structures.
b. Explain why this is an important reaction.

7. The molecule below is a simplified glyceraldehyde-3-phosphate.
a. Draw the product of glyceraldehyde-phosphate dehydrogenase using the same style.
b. Repeat with the remaining glycolysis reactions.

8. The diagram on the left represents the active site of GAPDH with NAD⁺ bound.
The diagram on the right represents an intermediate in the reaction.
a. Add a molecule of glyceraldehyde-3-phosphate to the left diagram and circle the
       carbon that will be oxidized by the enzyme.
b. Add a molecule of phosphate to the right diagram; draw an arrow to show where
       the phosphate will form a bond.
c. What mechanism(s) of enzyme catalysis does GAPDH use?

9. Draw the structures of the substrate and product for lactate dehydrogenase.
What part of the substrate is changed during the reaction, and how is it changed?
How is this reaction related to the reaction catalyzed by GAPDH?

10. For the half reaction pyruvate + 2 e⁻ + 2 H⁺ → lactate, E°′   =   − 0.185 V .
For the half reaction   NAD⁺ + 2 e⁻ + 2 H⁺ → NADH, E°′ is − 0.320 V.
Write the whole reaction in the spontaneous direction and calculate ΔG°′.

11. Draw the structures of the substrate and product for alcohol dehydrogenase.
What part of the substrate is changed during the reaction, and how is it changed?
How is this change like the change in question 9?

12. Draw the structures of the substrate and product for pyruvate decarboxylase.

top of page