CHEM 153C Midterm: CMP Pathway study questions

• School: UCLA
• Department: Chemistry and Biochemistry
• Course: CHEM 153C
• Professor: Weiss Richard

Document Summary

Glycolysis: the central metabolic pathways are said to be amphibolic. They are involved in both biosynthetic and catabolic metabolism: the tricarboxylic acid cycle is amphibolic. Amphibolic pathways are involved in both anabolism (biosynthesis) and catabolism (degradation). Uptake of glucose depends on the difference in glucose concentration between the blood and the cytosol. [glucose] is reduced by phosphorylating glucose to glucose-6-p. If glucose-6-p is not metabolized it inhibits hexokinase resulting in elevation of cytosolic [glucose] and reduction in further glucose uptake: phosphoglucose isomerase catalyzes the following reaction in glycolysis: The isomerization of glucose-6-p to fructose-6-p moves the carbonyl (c=o) from c1 to c2 facilitating the symmetrical aldol cleavage to two 3-carbon sugars. Fructose-6-p provides an alternative substrate for production of erythrose-4-p and ribose-5-p via the reversible reactions of the pentose phosphate pathway: (a) name the enzyme catalyzing the rate-limiting step in glycolysis. Phosphofructokinase (b) briefly indicate what is meant by a rate-limiting step.