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The Enzymes of Glycolysis

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What are the various strategies used to regulate glycolysis (do not include glycogen phosphorylase in this question), but include how various inhibitors and activators function, how a highly endergonic reaction is facilitated, and what the roles of isozymes are.

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Glycolysis is a tightly regulated event in the cell. Glucose flux is regulated to achieve constant ATP levels by regulation of three glycolytic enzymes. This regulation is allosteric in that the concentration of key metabolites that reflect the cellular balance between ATP production and consumption is in consideration.

Coordinated Regulation of Glycolysis and Gluconeogenesis:

Three glycolytic enzymes are subject to allosteric regulation [actually 4 if you include glycogen phosphorylase]: hexokinase IV, phosphofructokinase-1(PFK-1), and pyruvate kinase.

Hexokinase IV (glucokinase) is sequestered in the nucleus of the hepatocyte, but is released when the cytosolic glucose concentration rises. Hexokinase is an isoenzyme.

PFK-1 is allosterically ...

Solution Summary

The solution provides a detailed explanation of the strategies for regulating glycolysis. Included are explanations of inhibitors, activators, and isozymes. Detailed diagrams are also provided as attachments.

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Whether it was volcanic activity that spewed sulfur dioxide and ash into the atmosphere, or a giant meteor that crashed into the Earth blasting dust and debris into the sky, both theories of what caused the dinosaurs to become extinct share one critical similarity -- light from the sun was obliterated. The result of the months' long darkness was the mass extinction of nearly 70% of all creatures on Earth.

Like the dinosaurs, humans cannot live without the sun. Not only does it provide light and warmth, it is also the energy source for arguably the most important chemical reaction on Earth: photosynthesis.

Answer the following assignment questions:
1. Explain how photosynthesis and respiration are linked in order to provide you with energy from the food you eat:
- Complete descriptions of photosynthesis and aerobic respiration.
- Describe how these two processes are linked between plants and animals based on the reactants and products (water, carbon dioxide, glucose and oxygen) of both pathways.
- Include a description of how energy is transferred from sunlight to ATP, from ATP to sugars, and from sugars to your cells.

2. In the absence of oxygen some cells and organisms can use glycolysis coupled to fermentation to produce energy from the sugar created by photosynthesis:
- Explain the role of fermentation in allowing an organism to generate energy for its cell(s) in the absence of oxygen.
- Include any reactions required for this process, and explain how the energy from the sun ends up as chemical energy for the anaerobic organism or cell.

3. Cells use enzymes as biological catalysts to increase or accelerate the rate of reactions, such as those in photosynthesis or glycolysis. This allows reactions to occur under conditions that sustain life.
- Explain how an enzyme catalyzes a reaction. Include in your essay the three main steps of the cycle of enzyme-substrate interactions.
- How is enzyme activity regulated by the cell?

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