Glycolysis Energetics - Biochemistry
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For each mol of glucose oxidized via cellular respiration, how many total moles of ATP are generated through substrate-level phorphorylation?
For each mol of glucose oxidized via cellular respiration, how many total moles of ATP are generated through substrate-level phorphorylation?
Cellular respiration is a long process, and so it is easiest to break it into the following steps:
Step 1: Glycolysis
Step 2: Pyruvate decarboxylation
Step 3: Krebs cycle
Step 4: Oxidative phosphorylation
In the above steps, ATP is only produced by substrate-level phosphorylation in glycolysis and during the Krebs cycle.
In glycolysis, two molecules of pyruvate are produced for every molecule of glucose oxidized. During this process, two ATP molecules are consumed, but four are produced via substrate-level phosphorylation.
In the Krebs cycle, each pass of pyruvate through the cycle generates one molecule of GTP, which is subsequently used to generate a molecule of ATP via substrate-level phosphorylation. Thus, one molecule of ATP is produced via substrate-level phosphorylation per molecule of pyruvate oxidized. But remember that glycolysis produces two molecules of pyruvate for each molecule of glucose oxidized. Hence, the Krebs cycle will contribute a total of two molecules of ATP per glucose molecule oxidized.
Since we have a total of four moles ATP from glycolysis and two moles of ATP from the Krebs cycle (one per pyruvate), we have a cumulative production of six moles of ATP generated by substrate-level phosphorylation per mole of glucose oxidized.
Cellular respiration is a long process, and so it is easiest to break it into the following steps:
Step 1: Glycolysis
Step 2: Pyruvate decarboxylation
Step 3: Krebs cycle
Step 4: Oxidative phosphorylation
In the above steps, ATP is only produced by substrate-level phosphorylation in glycolysis and during the Krebs cycle.
In glycolysis, two molecules of pyruvate are produced for every molecule of glucose oxidized. During this process, two ATP molecules are consumed, but four are produced via substrate-level phosphorylation.
In the Krebs cycle, each pass of pyruvate through the cycle generates one molecule of GTP, which is subsequently used to generate a molecule of ATP via substrate-level phosphorylation. Thus, one molecule of ATP is produced via substrate-level phosphorylation per molecule of pyruvate oxidized. But remember that glycolysis produces two molecules of pyruvate for each molecule of glucose oxidized. Hence, the Krebs cycle will contribute a total of two molecules of ATP per glucose molecule oxidized.
Since we have a total of four moles ATP from glycolysis and two moles of ATP from the Krebs cycle (one per pyruvate), we have a cumulative production of six moles of ATP generated by substrate-level phosphorylation per mole of glucose oxidized.
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Energy is __________ during glycolysis.
Energy is __________ during glycolysis.
The first and third steps of glycolysis involve energy consumption in the form of ATP. A phosphate group is added to glucose, and fructose-6-phosphate. In the seventh and tenth steps of glycolysis, ADP is phosphorylated at the level of the substrate into ATP. Since this is after glucose had been split into two three-carbon molecules, each molecule of glucose results in four ATP produced. However, since two were consumed early in glycolysis, the net ATP production is 2.
The first and third steps of glycolysis involve energy consumption in the form of ATP. A phosphate group is added to glucose, and fructose-6-phosphate. In the seventh and tenth steps of glycolysis, ADP is phosphorylated at the level of the substrate into ATP. Since this is after glucose had been split into two three-carbon molecules, each molecule of glucose results in four ATP produced. However, since two were consumed early in glycolysis, the net ATP production is 2.
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Which steps in glycolysis convert ATP to ADP?
Which steps in glycolysis convert ATP to ADP?
The first step of glycolysis is the addition of a phosphate group to glucose to form glucose-6-phosphate. The third step of glycolysis is the addition of another phosphate group to fructose-6-phosphate to form fructose-1,6-bisphosphate. The conversion of ATP to ADP is needed to supply the phosphate group in both of these reactions. These are the only two reactions in glycolysis where ATP is used to to add phosphate groups.
The first step of glycolysis is the addition of a phosphate group to glucose to form glucose-6-phosphate. The third step of glycolysis is the addition of another phosphate group to fructose-6-phosphate to form fructose-1,6-bisphosphate. The conversion of ATP to ADP is needed to supply the phosphate group in both of these reactions. These are the only two reactions in glycolysis where ATP is used to to add phosphate groups.
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What is the net ATP yield of glycolysis?
What is the net ATP yield of glycolysis?
Glycolysis produces 4 ATP molecules. However, 2 ATP molecules are required to initiate glycolysis. Subtracting these two numbers gives the net ATP yield from glycolysis--2 ATP molecules.
Glycolysis produces 4 ATP molecules. However, 2 ATP molecules are required to initiate glycolysis. Subtracting these two numbers gives the net ATP yield from glycolysis--2 ATP molecules.
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Why might glycolysis not proceed for an organism even when it is given glucose, 
, 
, and water?
Why might glycolysis not proceed for an organism even when it is given glucose,
Although glycolysis will ultimately produce 4 ATP, there is an initial requirement of 2 ATP for it to begin. The conversion of glucose to glucose-6-phosphate and the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate both require ATP.
Although glycolysis will ultimately produce 4 ATP, there is an initial requirement of 2 ATP for it to begin. The conversion of glucose to glucose-6-phosphate and the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate both require ATP.
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During the energy investment phase of glycolysis, how many ATP are required to continue with the reactions per glucose molecule?
During the energy investment phase of glycolysis, how many ATP are required to continue with the reactions per glucose molecule?
The first and third steps of glycolysis are both energetically unfavorable. This means they will require an input of energy in order to continue forward. Per glucose molecule, 1 ATP is required for each of these steps. Therefore, a total of 2 ATP is needed during the energy investment phase of glycolysis.
The first and third steps of glycolysis are both energetically unfavorable. This means they will require an input of energy in order to continue forward. Per glucose molecule, 1 ATP is required for each of these steps. Therefore, a total of 2 ATP is needed during the energy investment phase of glycolysis.
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Which of the following is characteristic of hexokinase (as opposed to glucokinase)?
Which of the following is characteristic of hexokinase (as opposed to glucokinase)?
Hexokinase and glucokinase are two enzymes that serve similar roles but have different characteristics. Hexokinase is found in all tissues, is inhibited by glucose 6 phosphate, and is not induced by insulin. It has a physiologic role of providing cells with a basal level of glucose 6 phosphate necessary for energy production.
Hexokinase and glucokinase are two enzymes that serve similar roles but have different characteristics. Hexokinase is found in all tissues, is inhibited by glucose 6 phosphate, and is not induced by insulin. It has a physiologic role of providing cells with a basal level of glucose 6 phosphate necessary for energy production.
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While glycolysis results in the production of 4 ATP molecules, 2 must be used in the process. This results in a net production of only 2 ATP molecules per glucose.
What is the purpose of the 2 ATP molecules used in glycolysis?
While glycolysis results in the production of 4 ATP molecules, 2 must be used in the process. This results in a net production of only 2 ATP molecules per glucose.
What is the purpose of the 2 ATP molecules used in glycolysis?
In the glycolytic pathway, 2 molecules of ATP must be used. The purpose of these molecules is to phosphorylate 2 intermediates in the pathway:
1. Glucose must be phosphorylated to glucose-6-phosphate.
2. Fructose-6-phosphate must be phosphorylated to fructose-1,6-bisphosphate.
In the glycolytic pathway, 2 molecules of ATP must be used. The purpose of these molecules is to phosphorylate 2 intermediates in the pathway:
1. Glucose must be phosphorylated to glucose-6-phosphate.
2. Fructose-6-phosphate must be phosphorylated to fructose-1,6-bisphosphate.
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