Pentose phosphate pathway pq.pdf

THE PENTOSE PHOSPHATE PATHWAY 1. The pentose phosphate pathway is an alternative metabolic pathway for glucose oxidation that generates no _______________________. 2. The principal products of the pentose phosphate pathway are _______________________ and ribose-5-phosphate. 3. The pentose phospha...

THE PENTOSE PHOSPHATE PATHWAY 1. The pentose phosphate pathway is an alternative metabolic pathway for glucose oxidation that generates no _______________________. 2. The principal products of the pentose phosphate pathway are _______________________ and ribose-5-phosphate. 3. The pentose phosphate pathway occurs in the _______________________ in two phases. 4. The two phases of the pentose phosphate pathway are the _______________________ phase and the nonoxidative phase. 5. Ribose-5-phosphate is a structural component of _______________________ and nucleic acids. Answers: 1. ATP 2. NADPH 3. cytoplasm 4. oxidative 5. nucleotides INTRO Here are the fill-in-the-gap questions: 1. In the oxidative phase of the pentose phosphate pathway, the conversion of glucose-6-phosphate to ribulose-5-phosphate produces _______________________ molecules of NADPH. 2. The nonoxidative phase of the pentose phosphate pathway involves the _______________________ and condensation of sugar molecules. 3. Three useful intermediates in the nonoxidative phase of the pentose phosphate pathway are _______________________, fructose-6-phosphate, and glyceraldehyde-3-phosphate. Answers: 1. two 2. isomerization 3. ribose-5-phosphate OXIDATIVE STAGE Here are the fill-in-the-gap questions: 1. The oxidative phase of the pentose phosphate pathway consists of _______________________ reactions. 2. In the first reaction of the oxidative phase, glucose-6-phosphate is oxidized by the enzyme _______________________. 3. The products of the first reaction in the oxidative phase are 6-phosphogluconolactone and _______________________. 4. 6-Phosphogluconolactone is then hydrolyzed to produce _______________________. 5. A second molecule of NADPH is produced during the oxidative decarboxylation of _______________________. 6. The oxidative phase of the pentose phosphate pathway is most active in cells that synthesize relatively large amounts of _______________________. 7. The oxidative phase is also active in cells at high risk for _______________________ damage. 8. NADPH is a powerful _______________________. Answers: 1. three 2. glucose-6-phosphate dehydrogenase (G-6PD) 3. NADPH 4. 6-phospho-D-gluconate 5. 6-phosphogluconate 6. lipids 7. oxidative 8. antioxidant NON-OXIDATIVE STAGE Here are the fill-in-the-gap questions: 1. The nonoxidative phase of the pentose phosphate pathway begins with the conversion of ribulose-5-phosphate to _______________________ by ribulose-5-phosphate isomerase. 2. Transketolase is a _______________________ requiring enzyme that transfers two-carbon units from a ketose to an aldose. 3. Transketolase catalyzes two reactions, one of which transfers a two-carbon unit from xylulose-5-phosphate to _______________________. 4. Transaldolase transfers _______________________ units from a ketose to an aldose. 5. The result of the nonoxidative phase of the pathway is the synthesis of _______________________ and the glycolytic intermediates glyceraldehyde-3-phosphate and fructose-6-phosphate. 6. The pentose phosphate pathway is also referred to as the _______________________ shunt. 7. In plants, the pentose phosphate pathway is involved in the synthesis of _______________________ during the dark reactions of photosynthesis. 8. The oxidative phase is very active in cells such as _______________________ in which demand for NADPH is high. 9. G-6-PD catalyzes a key regulatory step in the pentose phosphate pathway, and its activity is _______________________ by NADPH. 10. Diets high in _______________________ increase the synthesis of both G-6-PD and phosphogluconate dehydrogenase. Answers: 1. ribose-5-phosphate 2. TPP (thiamine pyrophosphate) 3. ribose-5-phosphate 4. three-carbon 5. ribose-5-phosphate 6. hexose monophosphate 7. glucose 8. red blood cells 9. inhibited 10. carbohydrate