Glycolysis Steps 5 and 6

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Questions and Answers

What is the product of the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase?

phosphoenol pyruvate

2-phospho glycerate

1,3-bisphospho glycerate (correct)

3-phospho glycerate

What is the result of the spontaneous isomerization of enol pyruvate?

Formation of keto pyruvate (correct)

Conversion of pyruvate to lactate

Breakdown of glucose

Generation of ATP

What type of phosphorylation occurs in Step 6 of Glycolysis?

Electron transport chain

Substrate level phosphorylation (correct)

Non-reversible phosphorylation

Oxidative phosphorylation

What is the function of fluoride in blood sugar estimation?

To inhibit enolase and stop glycolysis (A) Signup and view all the answers

What is the function of pyruvate kinase in glycolysis?

To generate ATP through substrate level phosphorylation (A) Signup and view all the answers

In anaerobic conditions, what is the end product of glycolysis?

Lactate (D) Signup and view all the answers

What is the name of the enzyme that catalyzes the conversion of 3-phospho glycerate to 2-phospho glycerate?

Phosphogluco mutase (D) Signup and view all the answers

What is the purpose of lactate production in glycolysis?

To regenerate NAD+ in the cytoplasm (B) Signup and view all the answers

What is the role of NAD+ in Step 5 of Glycolysis?

To oxidize the aldehyde group (A) Signup and view all the answers

Why is lactate production necessary in muscle cells during exercise?

Because of limited oxygen availability (C) Signup and view all the answers

What is the product of the reaction catalyzed by pyruvate kinase?

Pyruvate (C) Signup and view all the answers

Where do red blood cells (RBCs) derive energy from?

Glycolysis (D) Signup and view all the answers

What type of reaction occurs during the conversion of 2-phosphoglycerate to phosphoenol pyruvate?

Dehydration (C) Signup and view all the answers

What is the role of Mg++ in Step 8 of Glycolysis?

To activate enolase (C) Signup and view all the answers

What is the significance of step 10 in glycolysis?

Regeneration of NAD+ (C) Signup and view all the answers

What is the name of the cycle that lactate enters after being produced in anaerobic glycolysis?

Cori's cycle (A) Signup and view all the answers

Study Notes

an=not; aer=air; bios=life). LDH has 5 iso-enzymes. The cardiac iso-enzyme of LDH will be increased in myocardial infarcts. A summary of glycolysis is shown in Fig. 9.4. In aerobic conditions, the pyruvate enters the citric acid cycle for complete oxidation. The end product of anaerobic glycolysis is lactate which enters the Cori's cycle. Significance of Lactate Production Steps 5 and 10 are Coupled In the 5th step, for each molecule of glucose entering in the pathway, two molecules of NAD+ are reduced to NADH. The availability of co-enzymes inside a cell is limited. Therefore, this step becomes a bottleneck in the whole reaction sequence. For smooth operation of the pathway, the NADH is to be reconverted to NAD+. This can be done by oxidative phosphorylation. However, during exercise, there is lack of oxygen. So this reconversion is not possible. Therefore, the cell has to couple some other reaction in which NAD+ is regenerated in the cytoplasm itself. Hence, pyruvate is reduced to lactate; the NAD+ thus generated is reutilised for uninterrupted operation of the pathway (Fig. 9.15). In RBCs, there are no mitochondria. Hence RBCs derive energy only through glycolysis, where the end product is lactic acid.

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Description

Learn about the fifth and sixth steps of glycolysis, including the dehydrogenation and phosphorylation of glyceraldehyde-3-phosphate and the synthesis of ATP with the help of bisphosphoglycerate kinase.