Exam 3 Exam Flashcards
The process of glycolysis occurs in _________.
virtually all organisms
In glycolysis, what type of enzyme catalyzes the interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate?
isomerase
In glycolysis, what type of enzyme catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate?
isomerase
Which statement below best describes ATP use/production for the series of reactions that convert one molecule of glucose to one molecule of glyceraldehyde-3-phosphate and one molecule of dihydroxyacetone phosphate?
2 ATP are used and 0 ATP are generated for a net yield of -2 ATP.
Glycolysis is the process of converting glucose to pyruvate. How many molecules of pyruvate are produced per glucose, and how many molecules of CO2 are released?
2 molecules pyruvate, 0 molecules CO2
Which glycolysis reaction(s) below requires ATP as a substrate?
(a) 3-phosphoglycerate → 2-phosphoglycerate
(b) glyceraldehyde-3-phosphate → dihydroxyacetone phosphate
Correct Answer
(c) glucose → glucose-6-phosphate
(c) glucose → glucose-6-phosphate
In glycolysis, the conversion of phosphoenolpyruvate to pyruvate is catalyzed by what type of enzyme?
kinase
What class of enzymes catalyzes the conversion of pyruvate to lactate?
dehydrogenase
The regeneration of ____ in the reduction of pyruvate to ethanol sustains glycolysis under anaerobic conditions.
NAD+
Gluconeogenesis utilizes a lot of the same reactions as glycolysis but in reverse. There are however a few unique steps in the gluconeogenesis pathway. Given reactions for GLYCOLYSIS below and their respective ΔG values under typical physiological conditions, which reaction would you expect would not be easily reversible in gluconeogenesis?
fructose-6-phosphate → fructose-1,6-bisphosphate ΔG = -22.2 kJ/mol
In gluconeogenesis, glucose-6-phosphate is converted into glucose by what type of enzyme?
phosphatase
How many nucleotide triphosphates (ATP and GTP) are required to convert two molecules of pyruvate into one molecule of glucose?
6
In actively respiring muscle tissue, lactate can be transported to the liver where it can be converted back to glucose and then transported back to the muscle tissue. What is this process called?
Cori cycle
Pyruvate is converted to acetyl CoA by pyruvate dehydrogenase. Which of the following is not a cofactor/cosubstrate for pyruvate dehydrogenase? thiamine pyrophosphate lipoamide NAD+ FAD
all of the above are either cofactors or cosubstrates for pyruvate dehydrogenase
The condensation of acetyl CoA with oxaloacetate to form citrate is catalyzed by what type of enzyme?
synthase
In which TCA cycle reaction below, is CO2 released as a product? citrate → isocitrate acetyl CoA + oxaloacetate → citrate α-ketoglutarate → succinyl CoA fumarate → malate
α-ketoglutarate → succinyl CoA
Which TCA cycle reaction below does NOT occur with reduction of NAD+ to NADH?
citrate → isocitrate
The yield from one mole of acetyl-CoA that completes the TCA cycle is (i) how many NADH, (ii) how many FADH2, and (iii) how many moles of GTP (or equivalents of ATP)? (Consider only the products of the TCA cycle reactions- do not include products from glycolysis or the pre-TCA cycle step.)
(i) 3 (ii) 1 (iii) 1
Why can plants invoke the net synthesis of glucose from the acetyl-CoA generated by the breakdown of fats, while animals cannot?
Both (a) and (b) are correct statements.
The glyoxylate cycle allows for bypass of the TCA cycle reactions that liberate carbon as CO2.
(b) The glyoxylate cycle allows for the net conversion of acetyl-CoA to oxaloacetate.
Where do the reactions of the TCA cycle take place in a eukaryotic cell?
mitochondrial matrix
Which enzyme catalyzes the reduction of O2?
Complex IV (cytochrome c oxidase)
The electrons from NADH enter the electron transport chain at which complex?
Complex I
Electrons from which complex(es) in the electron transport chain are transferred to Coenzyme Q?
(a) Complex I
(b) Complex II
The ATP synthase of the mitochondrial electron transport chain uses the energy contained in the H+ concentration gradient to __________.
release ATP bound to the complex after synthesis
