34 Questions
What is the enzyme responsible for converting fructose 1,6-bisphosphate to fructose 6-phosphate?
Fructose 2,6-bisphosphatase
What is the purpose of the reciprocal actions of fructose 2,6-bisphosphate on glycolysis and gluconeogenesis?
To prevent a futile cycle
What is the net result of the reciprocal actions of fructose 2,6-bisphosphate?
Prevention of a futile cycle
What is the role of citrate in the regulation of glycolysis and gluconeogenesis?
Inhibits phosphofructokinase-1
What is the effect of high ATP levels on phosphofructokinase-1?
Inhibition
What is the effect of high AMP levels on phosphofructokinase-1?
Activation
What is the full form of GDP?
Guanosine diphosphate
What is the function of cAMP phosphodiesterase?
To hydrolyze cAMP to 5'-AMP
What is the role of 5'-AMP in cellular signaling?
It is not an intracellular signaling molecule
What happens to the effects of neurotransmitter- or hormone-mediated increases of cAMP when the extracellular signal is removed?
They are rapidly terminated
What is the full form of cAMP?
Cyclic adenosine monophosphate
What is the relationship between cAMP and GTP?
cAMP and GTP are structurally similar
What is the primary function of catabolic reactions?
To capture chemical energy in the form of ATP
What is the result of a pathway being blocked, for example, by a drug or an inherited deficiency of an enzyme?
A decrease in the flow of intermediate molecules
What is the role of molecules in the diet or stored in cells in catabolic pathways?
They are converted into building blocks needed for the synthesis of complex molecules
What is the purpose of repeatedly featuring pathways in the major metabolic maps?
To depict the effect of blocking a pathway on the flow of intermediate molecules
What is the molecule that captures chemical energy in catabolic reactions?
ATP (Adenosine Triphosphate)
What is the ultimate goal of energy generation by catabolic pathways?
To store energy in the form of ATP
What is the first oxidation-reduction reaction of glycolysis?
Conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate
What is the product of the first oxidation-reduction reaction of glycolysis?
1,3-bisphosphoglycerate
Why is the reoxidation of NADH to NAD+ necessary?
To continue glycolysis
What is the byproduct of the first oxidation-reduction reaction of glycolysis?
NADH + H+
What are the two major mechanisms for oxidizing NADH?
NADH-linked conversion of pyruvate to lactate and oxidation of NADH via the respiratory chain
What is the purpose of oxidizing NADH?
To continue glycolysis
What is the reactant of the first oxidation-reduction reaction of glycolysis?
Glyceraldehyde 3-phosphate
What is the enzyme responsible for the first oxidation-reduction reaction of glycolysis?
Glyceraldehyde 3-phosphate dehydrogenase
What is the byproduct of the oxidation of the aldehyde group of glyceraldehyde 3-phosphate?
Carboxyl group
What is the function of the high-energy phosphate group at carbon 1 of 1,3-BPG?
To drive the synthesis of ATP
What is the result of the oxidation of glyceraldehyde 3-phosphate?
The formation of a carboxyl group
What is the role of phosphatase in glycolysis?
To remove phosphate groups from substrates
What is the energy source for the synthesis of ATP in glycolysis?
The oxidation of glyceraldehyde 3-phosphate
What is the product of the reaction involving the attachment of Pi to the carboxyl group?
1,3-BPG
What is the function of the mutation of glyceraldehyde 3-phosphate?
To drive the synthesis of ATP
What is the outcome of the coupling of the oxidation of glyceraldehyde 3-phosphate with the attachment of Pi to the carboxyl group?
The synthesis of 1,3-BPG and ATP
Study Notes
Metabolic Intermediates and Pathways
- Metabolic pathways depict the effects of blocking a pathway (e.g., by a drug or inherited enzyme deficiency) on the flow of intermediates.
Catabolic Pathways
- Catabolic reactions capture chemical energy from the degradation of energy-rich fuel molecules, storing it in the form of ATP (adenosine triphosphate).
- Catabolism allows molecules in the diet (or nutrient molecules stored in cells) to be converted into building blocks needed for the synthesis of complex molecules.
Energy Generation
- Energy is generated by catabolic pathways, which break down energy-rich molecules to produce ATP.
Regulatory Mechanisms
- The effects of neurotransmitter- or hormone-mediated increases of cAMP are rapidly terminated when the extracellular signal is removed.
- Fructose 2,6-bisphosphate plays a key role in regulating glycolysis and gluconeogenesis, ensuring that both pathways are not fully active at the same time.
Glycolysis
- Glycolysis is a catabolic pathway that converts glucose into pyruvate.
- The conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate (1,3-BPG) is the first oxidation-reduction reaction of glycolysis.
- The high-energy phosphate group at carbon 1 of 1,3-BPG conserves much of the free energy produced by the oxidation of glyceraldehyde 3-phosphate.
- The energy of this high-energy phosphate drives the synthesis of ATP in the next reaction of glycolysis.
Oxidation of Glyceraldehyde 3-Phosphate
- The oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate is catalyzed by glyceraldehyde 3-phosphate dehydrogenase.
- This reaction is the first oxidation-reduction reaction of glycolysis.
- The NADH formed by this reaction must be reoxidized to NAD+ for glycolysis to continue.
NADH Reoxidation
- Two major mechanisms for oxidizing NADH are:
- The NADH-linked conversion of pyruvate to lactate (anaerobic)
- Oxidation of NADH via the respiratory chain (aerobic)
This quiz covers metabolic pathways and catabolic reactions, including how they are affected when a pathway is blocked. It explores the major metabolic maps and the capture of chemical energy.
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