EXAM 3 Flashcards
The reaction pathway that transforms fuels into cellular energy
Catabolic
The metabolic pathways the require energy and are often biosynthetic processes
Anabolic
Which energy source is used to regenerate ATP from ADP and Pi
oxidation of carbon to CO2
What are the major purposes for which organisms require energy
- the performance of mechanical work
- active transport
- the synthesis of biomolecules
What is the standard-state free energy for the hydrolysis of ATP to ADP
-30kJ/mol
Electron donor used for reductive biosynthesis
NADPH
Activated carriers that contain adenosine phosphate groups
- NADH
- FADH2
- coenzyme A
Metabolic processes are regulated by
- Transcriptional regulation of the amount of enzyme
- allosteric control of enzyme activity
- the accessibility of substrates by compartmentalization
Organisms that use energy from sunlight and convert to chemical energy
Phototrophs
Organisms that obtain chemical energy from the oxidation of foodstuffs
Chemotrophs
Pathways can be either anabolic or catabolic, depending on the energy conditions of the cell
Amphibolic
In aerobic organisms, the ultimate acceptor of electrons is
Oxygen
In aerobic metabolism, the product of oxidation of carbon containing fuels is
Carbon Dioxide
The electron carrier, NADH, is derived from the _______ vitamin
Niacin
The chemical currency of metabolism
ATP
FAD is an electron carrier that is derived from the vitamin
Riboflavin (B2)
NADH and NADPH
niacin
FADH2
riboflavin
acetyl CoA
pantothenate
Biotin
biotin
Tetrahydrofolate
folate
The principle carbohydrate in living systems
Glucose
The product of aerobic glycolysis
2 pyruvate
The substance _______ must be regenerated for glycolysis to proceed in either aerobic or aerobic conditions
NAD+
An allosteric activator of glycolysis is
AMP
Glycolysis produces a net of ____ moles of ATP
2
The key regulatory enzyme for glycolysis is
PFK
________ are enzymes that catalyze the transfer of phosphoryl group from ATP to an acceptor
Kinases
In alcoholic fermentation, the decarboxylation of pyruvate requires a coenzyme that contains the vitamin_____
Thiamine (B1)
A potent allosteric activator of liver PFK if ________, which is produced from fructose-6–phosphate by PFK2
F 2,6-biphosphate
_________ mediate the thermodynamically downhill movement of glucose across plasma membranes
Glucose transporters
How is glycolysis maintained under anaerobic conditions?
Pyruvate can be reduced to either lactate or ethanol; this reaction is accompanied by the oxidation of NADH to regenerate NAD+
Which of the following is a reason that glucose is a common metabolic fuel used by living organisms?
Answers: A. It has a stable ring structure and is unlikely to glycosylate proteins. B. It has been found as one of the monosaccharides formed under prebiotic conditions. C. It is the only sugar used by the brain. D. A and B
A and B
What is the purpose of phosphorylating glucose in cytosol? A. to trap glucose in the cell B. to destabilize glucose and facilitate the next series of metabolic steps C. to convert it to a more soluble form D. A and B
A and B
What reaction is catalyzed by aldolase
reversible cleavage of F-1,6-BP to DHAP and GAP
What is the function of a thirster intermediate such as the one formed from GAP
The thirster allows the two-step reaction to be coupled so that the second reaction, the energetically unfavorable phosphorylation, can proceed
What is substrate-level phosphorylation?
ATP synthesis when the phosphate donor is a substrate with high-phosphoryl-transfer potential
What type of enzyme catalyzes the intramolecular shift of a chemical group?
Mutase
What are the primary metabolic fates of pyruvate? A. ethanol B. lactate C. acetyl CoA D. All of the above.
All of the above
Lactose intolerance is caused by a deficiency of
Lactase
Fructose from table sugar or high-fructose corn syrup and galactose form milk sugar converted to
glycolytic intermediates
During exercise, glycolysis is stimulated by a
feed-forward stimulation of pyruvate kinase
The process by which non carb precursor molecules are converted into glucose
Gluconeogensis
The stores of glucose are enough to support metabolism of a person for
1 day
The major tissue in which gluconeogenesis takes place is in the
liver
The conversion of glucose 6-phosphate to glucose takes place in the
lumen of the ER
The reaction that uses GTP and not ATP as its high-phosphoryl transfer donor is
PEP carboxylase
The compound__________ activates glycolysis and inhibits gluconeogenesis via conversion of fructose 1,6-bisphophate
F-2,6-BP
controls the synthesis and degradation of F-2,6-BP
PFK2
An intermediate that is decarboxylated and phosphorated to produce phophoenopyruvate
oxaloacetate
This essential nutrient is required for the carboxylation of pyruvate in human
Biotin
The ______ cycle is responsible for converting muscle lactate into glucose in the liver
Cori
Glycerol from fats is modified first by glycerol kinase and then a second enzyme to enter gluconeogensis at the intermediate
DHAP
How does the liver restore the level of glucose for active muscles
By converting lactate to glucose through the cori cycle
Biotin is a _____ for the pyruvate carboxylase reaction
cofactor
The phosphoryl donor in the formation of phosphoenolpyruvate is
GTP
The phosphorylation of glucose 6-phosphate takes place in which cellular location
The ER lumen
High levels of ATP and citrate: Answers: A. indicate a high-energy–well-fed state. B. promote gluconeogenesis. C. inhibits glycolysis D. All of the above
All of the above
What is an inhibitor of PFK?
citrate