31 Questions
What is generated by glucose metabolism during a sprint when oxygen delivery is inadequate?
Lactate
What occurs in skeletal muscle during vigorous exercise?
Production of pyruvate > oxidation of pyruvate
What do red blood cells produce due to the lack of mitochondria?
Lactate
What happens to glucose metabolism when oxygen delivery is adequate?
It produces carbon dioxide and water
Under what condition is glucose metabolized to lactate?
Low oxygen levels
What type of metabolism is glycolysis classified as?
Catabolism
Where is the energy released during glycolysis stored?
As heat and in ATP and electron carriers
What is the main product of glycolysis?
Pyruvate
How many ATP molecules are produced in the pay-off phase of glycolysis?
4
Which enzyme is involved in the first step of glycolysis?
Hexokinase
Which product is formed in the third step of glycolysis?
Dihydroxyacetone phosphate
What is the role of enzymes in glycolysis?
To couple energy-requiring reactions to spontaneous reactions
Which pathway breaks down glucose to generate Ribose 5-phosphate?
Pentose phosphate pathway
Which phase of glycolysis requires the investment of ATP?
Preparatory phase
How many carbons does each pyruvate molecule contain?
3
Which enzyme is responsible for converting glucose to glucose 6-phosphate?
hexokinase
What cofactor is required by hexokinase to properly function?
magnesium
Which enzyme catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate?
phosphohexose isomerase
Fructose 6-phosphate is converted to which molecule in the third step of glycolysis?
fructose 1,6-bisphosphate
Which enzyme is involved in the breakdown of fructose 1,6-bisphosphate into DHAP and G3P?
aldolase
What is the main significance of the conversion of DHAP to G3P?
G3P is a more reactive molecule.
How many carbons are present in glucose?
6
Which type of enzyme is hexokinase?
transferase
Which enzyme is responsible for converting glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate?
Glyceraldehyde 3-phosphate dehydrogenase
In which step is ATP generated during the conversion of 1,3-bisphosphoglycerate to pyruvate?
Step 7
What is the immediate product of the reaction catalyzed by phosphoglycerate kinase?
3-phosphoglycerate
Which enzyme catalyzes the dehydration of 2-phosphoglycerate to phosphoenolpyruvate?
Enolase
Which molecule is used as an input in the conversion of 3-phosphoglycerate to 2-phosphoglycerate?
3-phosphoglycerate
What type of reaction is catalyzed by glyceraldehyde 3-phosphate dehydrogenase?
Redox Reaction
Which intermediate is considered unstable and quickly reacts to the next step?
2-phosphoglycerate
What is the end product of the conversion of phosphoenolpyruvate by pyruvate kinase?
Pyruvate
Study Notes
Anaerobic Reduction of Pyruvate to Lactate
- During high-intensity exercises like sprinting, glucose is metabolized to lactate when oxygen delivery is inadequate.
- In contrast, when oxygen delivery is adequate, glucose is metabolized to carbon dioxide and water.
Glucose Metabolism
- Glucose metabolism generates ATP to meet muscle contraction demands.
- Glycolysis is a metabolic pathway that breaks down glucose to produce energy.
- Energy released from glycolysis can be stored as ATP, heat, or electron carriers like NADH and NADPH.
Glycolysis
- Glycolysis breaks down glucose (a 6-carbon sugar) into pyruvate (a 3-carbon sugar).
- The process has two phases: preparatory and pay-off.
- The preparatory phase requires an investment of 2 ATPs and converts glucose into two 3-carbon molecules: DHAP and glyceraldehyde 3-phosphate.
- The pay-off phase invests 2 ATPs and produces 2 pyruvate, 4 ATPs, and 2 NADH.
Steps in Glycolysis
- There are 10 steps in glycolysis, involving specific enzymes and resulting in various products.
- The steps are:
- Glucose to Glucose 6-phosphate (hexokinase)
- Glucose 6-phosphate to Fructose 6-phosphate (phosphohexose isomerase)
- Fructose 6-phosphate to Fructose 1,6-bisphosphate (phosphofructokinase-1)
- Fructose 1,6-bisphosphate to DHAP and G3P (aldolase)
- DHAP to G3P (triose phosphate isomerase)
- G3P to 1,3-bisphosphoglycerate (glyceraldehyde 3-phosphate dehydrogenase)
- 1,3-bisphosphoglycerate to 3-phosphoglycerate (phosphoglycerate kinase)
- 3-phosphoglycerate to 2-phosphoglycerate (phosphoglycerate mutase)
- 2-phosphoglycerate to phosphoenolpyruvate (enolase)
- Phosphoenolpyruvate to Pyruvate (pyruvate kinase)
Glyceraldehyde-3-phosphate to Pyruvate
- This process involves the final 5 steps of glycolysis.
- The key features of these steps include redox reactions, substrate-level phosphorylation, and the formation of high-energy unstable bonds.
Important Notes
- Under low oxygen conditions, pyruvate may be converted to lactate.
- Pyruvate is typically used by mitochondria to generate ATP through the citric acid cycle and oxidative phosphorylation.
This quiz explains how glucose is metabolized to lactate during high-intensity activities like sprinting, and how oxygen delivery affects ATP production. It uses the example of Usain Bolt's record-breaking sprint to illustrate the concept.
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