Glycolysis Steps Overview

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Questions and Answers

What happens in Step 1 of Glycolysis?

A phosphate group is transferred from ATP to glucose (correct)

Glucose is converted to fructose

Dihydroxyacetone phosphate is produced

Fructose-1,6-bisphosphate is formed

What enzyme catalyzes Step 1 of Glycolysis?

Hexokinase

What is produced in Step 2 of Glycolysis?

Fructose-6-phosphate (correct)

Dihydroxyacetone phosphate

Glucose-6-phosphate

Fructose-1,6-bisphosphate

What enzyme is involved in Step 2?

Phosphoglucose Isomerase Signup and view all the answers

What occurs in Step 3 of Glycolysis?

Fructose-1,6-bisphosphate is produced Signup and view all the answers

Which enzyme regulates Step 3 of Glycolysis?

Phosphofructokinase Signup and view all the answers

What happens in Step 4 of Glycolysis?

Fructose-1,6-bisphosphate splits into two three-carbon sugars Signup and view all the answers

What enzyme is responsible for the reaction in Step 4?

Fructose Biphosphate Aldolase Signup and view all the answers

What occurs in Step 5 of Glycolysis?

DHAP is converted into glyceraldehyde-3-phosphate Signup and view all the answers

Which enzyme catalyzes Step 5?

Triose Phosphate Isomerase Signup and view all the answers

What is produced in Step 6 of Glycolysis?

1,3-bisphosphoglycerate is formed Signup and view all the answers

What is the function of the enzyme in Step 6?

Glyceraldehyde-3-Phosphate Dehydrogenase Signup and view all the answers

What action does Step 7 of Glycolysis accomplish?

ADP is converted into ATP Signup and view all the answers

Which enzyme is involved in Step 7?

Phosphoglycerate Kinase Signup and view all the answers

What transformation occurs in Step 8 of Glycolysis?

3-phosphoglycerate is converted to 2-phosphoglycerate Signup and view all the answers

What enzyme is used in Step 8?

Phosphoglycerate Mutase Signup and view all the answers

What occurs in Step 9 of Glycolysis?

2-phosphoglycerate is converted into phosphoenolpyruvate (PEP) Signup and view all the answers

What enzyme is involved in Step 9?

Enolase Signup and view all the answers

What happens in Step 10 of Glycolysis?

Pyruvate is produced Signup and view all the answers

What enzyme facilitates Step 10 of Glycolysis?

Pyruvate Kinase Signup and view all the answers

Regulatory Step #1 of Glycolysis is reversible.

False Signup and view all the answers

Regulatory Step #2 involves an allosteric enzyme.

True Signup and view all the answers

Regulatory Step #3 of Glycolysis is highly endergonic.

False Signup and view all the answers

Study Notes

Glycolysis Overview

Glycolysis occurs in the cytosol and is the metabolic pathway that converts glucose into pyruvate, producing ATP and NADH.
It is divided into two phases: the energy investment phase and the payoff phase.

Step 1: Glucose Phosphorylation

Glucose is phosphorylated by ATP to form glucose-6-phosphate.
Enzyme: Hexokinase.
Glucose-6-phosphate is more reactive and is unable to cross the membrane, trapping it inside the cell.

Step 2: Isomerization

Glucose-6-phosphate is converted into fructose-6-phosphate.
Enzyme: Phosphoglucose Isomerase.

Step 3: Second Phosphorylation

Fructose-6-phosphate is phosphorylated using ATP to form fructose-1,6-bisphosphate.
Enzyme: Phosphofructokinase (PFK).
PFK is an allosteric enzyme that regulates glycolysis based on energy needs.

Step 4: Cleavage

Fructose-1,6-bisphosphate splits into two three-carbon sugars: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P).
Enzyme: Fructose Biphosphate Aldolase.
Only G3P can continue in the glycolysis pathway.

Step 5: Isomerization of DHAP

DHAP is converted to G3P, with the equilibrium favoring G3P consumption.
Enzyme: Triose Phosphate Isomerase.
Marks the end of the energy investment phase, having consumed two ATP.

Step 6: Oxidation and Phosphorylation

G3P is oxidized, reducing NAD+ to NADH and forming 1,3-bisphosphoglycerate.
Enzyme: Glyceraldehyde-3-Phosphate Dehydrogenase.
This reaction generates energy for phosphorylation.

Step 7: Substrate-Level Phosphorylation

1,3-bisphosphoglycerate transfers a phosphate to ADP, producing ATP and forming 3-phosphoglycerate.
Enzyme: Phosphoglycerate Kinase.
This is the first substrate-level phosphorylation of glycolysis.

Step 8: Isomerization

3-phosphoglycerate is converted to 2-phosphoglycerate.
Enzyme: Phosphoglycerate Mutase.

Step 9: Dehydration

Water is removed from 2-phosphoglycerate, creating phosphoenolpyruvate (PEP), which is unstable.
Enzyme: Enolase.

Step 10: Final Phosphorylation

PEP donates its phosphate to ADP, yielding another ATP and forming pyruvate.
Enzyme: Pyruvate Kinase.
This final step concludes the payoff phase with a net gain of 2 ATP per glucose.

Regulatory Steps

Step 3 by Phosphofructokinase: First irreversible and highly exergonic, speeding up or slowing glycolysis.
Step 10 by Pyruvate Kinase: Final irreversible and highly exergonic, contributing to metabolic control.
Regulation of these steps ensures the glycolysis pathway is adjusted based on cellular energy status.

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Description

Explore the fundamental steps of glycolysis through a structured quiz. This quiz will guide you through the conversion process of glucose and emphasize the enzymes involved in each step. Perfect for students studying cellular respiration and metabolic pathways.