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Questions and Answers
The enzyme ______ catalyzes the transformation of sugars.
The enzyme ______ catalyzes the transformation of sugars.
transketolase
3 ribulose-5- P is a sugar with ______ carbons.
3 ribulose-5- P is a sugar with ______ carbons.
5
3 glucose-6- P is converted into 3 ______ in the process.
3 glucose-6- P is converted into 3 ______ in the process.
6-phosphogluconate
______ catalyzes one of the three sugar transformation reactions.
______ catalyzes one of the three sugar transformation reactions.
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The products of sugar transformations can be used for biosynthesis or to regenerate ______.
The products of sugar transformations can be used for biosynthesis or to regenerate ______.
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Fumarate reacts with H2O to form ______.
Fumarate reacts with H2O to form ______.
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The TCA cycle contains a ______-carbon stage and a ______-carbon stage.
The TCA cycle contains a ______-carbon stage and a ______-carbon stage.
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Isocitric acid is a key ______ in the TCA cycle.
Isocitric acid is a key ______ in the TCA cycle.
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The compound that reacts to yield fumarate is ______.
The compound that reacts to yield fumarate is ______.
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The reaction involving malate and fumarate is a part of the ______ cycle.
The reaction involving malate and fumarate is a part of the ______ cycle.
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The NADH and FADH2 formed by glycolysis and the ______ cycle are oxidized by an electron transport chain.
The NADH and FADH2 formed by glycolysis and the ______ cycle are oxidized by an electron transport chain.
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The 3-carbon, energy-conserving phase begins when fructose 1,6-bisphosphate is cleaved into two ______ molecules.
The 3-carbon, energy-conserving phase begins when fructose 1,6-bisphosphate is cleaved into two ______ molecules.
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Dihydroxyacetone phosphate is immediately converted to ______.
Dihydroxyacetone phosphate is immediately converted to ______.
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NADH is formed when glyceraldehyde 3-phosphate is oxidized with ______ as the electron acceptor.
NADH is formed when glyceraldehyde 3-phosphate is oxidized with ______ as the electron acceptor.
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A high-energy molecule called ______ is produced when a phosphate is incorporated during glycolysis.
A high-energy molecule called ______ is produced when a phosphate is incorporated during glycolysis.
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The phosphate on the first carbon of 1,3-bisphosphoglycerate is donated to ______ to produce ATP.
The phosphate on the first carbon of 1,3-bisphosphoglycerate is donated to ______ to produce ATP.
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In the 3-carbon phase of the pathway, both NADH and ______ are produced.
In the 3-carbon phase of the pathway, both NADH and ______ are produced.
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The major pathways that catabolize glucose to pyruvate include Embden-Meyerhof, Entner-Doudoroff, and ______ pathways.
The major pathways that catabolize glucose to pyruvate include Embden-Meyerhof, Entner-Doudoroff, and ______ pathways.
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We refer to these pathways collectively as ______ pathways or as glycolysis.
We refer to these pathways collectively as ______ pathways or as glycolysis.
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Glycolysis is divided into two main phases: the energy investment phase and the ______ phase.
Glycolysis is divided into two main phases: the energy investment phase and the ______ phase.
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The ______ phase gives a net yield of two ATP per glucose.
The ______ phase gives a net yield of two ATP per glucose.
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Glucose is phosphorylated at the expense of one ATP, generating glucose ______-phosphate.
Glucose is phosphorylated at the expense of one ATP, generating glucose ______-phosphate.
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Isomerization of glucose 6-phosphate (an aldehyde) to fructose ______-phosphate.
Isomerization of glucose 6-phosphate (an aldehyde) to fructose ______-phosphate.
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______ is consumed to phosphorylate C1 of fructose.
______ is consumed to phosphorylate C1 of fructose.
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The cell is spending some of its energy currency in order to earn more in the next ______ of the pathway.
The cell is spending some of its energy currency in order to earn more in the next ______ of the pathway.
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Glucose 6-phosphate is a precursor metabolite and the starting molecule for the pentose ______ pathway.
Glucose 6-phosphate is a precursor metabolite and the starting molecule for the pentose ______ pathway.
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Many reactions of this pathway are Energy ______.
Many reactions of this pathway are Energy ______.
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Some reactions are catalyzed by enzymes unique to the ______.
Some reactions are catalyzed by enzymes unique to the ______.
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Gluconeogenesis allows cells to synthesize ______ from smaller molecules.
Gluconeogenesis allows cells to synthesize ______ from smaller molecules.
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The ______ acid cycle increases metabolic efficiency.
The ______ acid cycle increases metabolic efficiency.
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These pathways are referred to as ______ pathways.
These pathways are referred to as ______ pathways.
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NAD+ is reduced to ______ in the catabolic direction of this pathway.
NAD+ is reduced to ______ in the catabolic direction of this pathway.
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The Embden-Meyerhof pathway is a type of ______ pathway.
The Embden-Meyerhof pathway is a type of ______ pathway.
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Some glycolytic reactions are not ______.
Some glycolytic reactions are not ______.
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The transaldolase enzyme converts Fructose-6-P to ______.
The transaldolase enzyme converts Fructose-6-P to ______.
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Transketolase is involved in the conversion of Fructose-6-P to ______ and Glyceraldehyde-3-P.
Transketolase is involved in the conversion of Fructose-6-P to ______ and Glyceraldehyde-3-P.
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The catabolism of three glucose 6-phosphate molecules generates ______ CO2 molecules.
The catabolism of three glucose 6-phosphate molecules generates ______ CO2 molecules.
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The Embden-Meyerhof pathway is also known as the ______ pathway.
The Embden-Meyerhof pathway is also known as the ______ pathway.
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During the degradation of glyceraldehyde 3-phosphate to pyruvate, ______ ATP are formed.
During the degradation of glyceraldehyde 3-phosphate to pyruvate, ______ ATP are formed.
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The pentose phosphate pathway produces reducing power in the form of ______.
The pentose phosphate pathway produces reducing power in the form of ______.
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Ribose 5-phosphate is a precursor for the macromolecule ______.
Ribose 5-phosphate is a precursor for the macromolecule ______.
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Glyceraldehyde 3-phosphate can enter the ______ phase of the Embden-Meyerhof pathway.
Glyceraldehyde 3-phosphate can enter the ______ phase of the Embden-Meyerhof pathway.
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Study Notes
Pathways Used by Chemoorganotrophs to Catabolize Organic Energy Sources
- Organic carbon sources can be used for energy or anabolic purposes
- Amphibolic pathways include enzymes that function both catabolically and anabolically
- Glycolysis and gluconeogenesis are distinct pathways but share some enzymes. Example of an amphibolic pathway: the Embden-Meyerhof pathway
- Aerobic respiration uses glycolytic pathways, the TCA cycle, and an electron transport chain, with oxygen as the final electron acceptor
- Fermentation uses only a subset of reactions from respiration, partially catabolizing the energy source without the use of an external electron acceptor
- Microbes use fermentation for food production (e.g., beer, cheese)
Embden-Meyerhof Pathway
- The most common pathway for glucose degradation to pyruvate
- Found in microorganisms, plants, and animals
- Functioning in presence or absence of oxygen
- Produces precursor metabolites, NADH, and ATP
- Divided into a 6-carbon phase and a 3-carbon phase
- The 6-carbon phase consumes ATP to phosphorylate glucose, leading to fructose-1,6-bisphosphate
- The 3-carbon phase produces NADH and ATP via substrate-level phosphorylation leading to pyruvate
- Net yield of 2 ATP per glucose
Entner-Doudoroff Pathway
- Used by some Gram-negative bacteria, but not eukaryotes
- Alternative pathway for glucose catabolism to pyruvate
- Produces one ATP, one NADH, and one NADPH per glucose
- Replaces the 6-carbon phase of the Embden-Meyerhof pathway, yielding pyruvate and glyceraldehyde 3-phosphate
Pentose Phosphate Pathway
- A major producer of reducing power for anabolic reactions
- Oxidative phase produces NADPH and precursor metabolites (e.g., erythrose 4-phosphate, ribose 5-phosphate). Erythrose 4-phosphate is used in amino acid synthesis, while ribose 5-phosphate is a component of nucleic acids
- The non-oxidative phase of the pathway allows the synthesis of glucose from various intermediates
- Amphibolic pathway used for both catabolism and anabolism
Pyruvate to Carbon Dioxide (Tricarboxylic Acid Cycle)
- Pyruvate is oxidized to acetyl-CoA, releasing CO2 and generating NADH.
- Acetyl-CoA enters the TCA cycle
- TCA cycle is also known as the citric acid cycle or Krebs cycle
- Oxidation of pyruvate to three CO2 molecules and the generation of NADH, FADH2, and GTP/ATP.
- Precursor metabolites are produced.
- The TCA cycle is crucial in energy conservation by generating NADH and FADH2, which donate electrons to the electron transport chain.
Electron Transport and Oxidative Phosphorylation
- The electron transport chain (ETC) uses NADH and FADH2 to generate a proton motive force (PMF).
- PMF is used to produce ATP via ATP synthase
- The ETC is crucial in generating the majority of ATP during aerobic respiration.
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Description
Explore the various pathways utilized by chemoorganotrophs to catabolize organic energy sources. This quiz covers amphibolic pathways, glycolysis, aerobic respiration, fermentation, and the Embden-Meyerhof pathway's significance in metabolism. Test your understanding of these essential biochemical processes.
