Reading Guide, Pratt and Cornely Chapter 13c
1. What is the starting material of the pentose phosphate pathway (PPP)? What are the two
products of the PPP? What percentage of glucose is processed through the PPP in liver cells?
2. Write the equation of the reaction catalyzed by glucose-6-phosphate dehydrogenase. How is
the NADPH cofactor used in the cell?
3. Write the equation of the reaction catalyzed by 6-phosphogluconolactonase. Is this reaction an
oxidation or not? Is this reaction spontaneous or not spontaneous under standard conditions?
4. Write the equation of the reaction catalyzed by 6-phosphogluconate dehydrogenase. Is this
reaction an oxidation or not?
5. What type of enzyme catalyzes the reaction of ribulose-5-P to ribose-5-P?
6. In fast growing, replicating cells, both ribose and NADPH are needed. Why? In cells that are
doing anabolic reactions but not dividing, which product of PPP is needed?
7. What types of enzymes catalyze the interconversion of sugars in the non-oxidizing phase of
the PPP? Draw a schematic of how three 5-carbon sugars can be made into 3- and 6-carbon
sugars utilizing the transfers of 2 or 3 carbon units.
8. Review Figure 13.12.