CHEM 153A Lecture 8: [Wk8.Fri] TCA and Pyruvate Dehydrogenase
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1. Choose the TWO correct statements describing the citrate cycle.
ATP is an indirect product of the citric acid cycle | |
Acetyl CoA can increase the pool of citric acid cycle intermediates | |
Fatty acids can increase the pool of citric acid cycle intermediates | |
ADP inhibits α-ketoglutarate dehydrogenase | |
The pool of mitochondrial oxaloacetate can be increased by pyruvate | |
All enzymes of the citric acid cycle are found soluble and free in the mitochondrial matrix |
2.Which molecule in the net reaction of the citrate cycle contributes to the inhibition of pyruvate dehydrogenase?
NADH | |
H+ | |
H2O | |
FAD |
3. How would a high NADH to NAD+ ratio be expected to affect the pyruvate dehydrogenase reaction?
The E1 subunit is phosphorylated by pyruvate dehydrogenase kinase, and the catalytic activity of pyruvate dehydrogenase decreases. | |
The last step of the pyruvate dehydrogenase reaction is blocked, resulting in a decrease in activity. | |
The pyruvate dehydrogenase phosphatase-1 enzyme would increase, resulting in pyruvate dehydrogenase activation at an accelerated rate. | |
The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an increase in pyruvate dehydrogenase activity. |
Several diseases are associated with malfunctioning of succinate dehydrogenase, including Leigh syndrome. In this disease, finding large quantities of lactate in the blood, urine, and cerebrospinal fluid is common. Why might this be the case?
A. Large quantities of succinate build up, leading to a downregulation of the electron transport chain |
B. Excess gluconeogenesis as a result of increased lactate production |
C. Glycolysis is inhibited because of inadequate NAD+ supply, leading to a downregulation in pyruvate concentration |
D. Pyruvate builds up because isn't broken down in TCA, lactate is produced from pyruvate |