Glycolysis

Q: What is glycolysis?
A: A metabolic process that breaks down glucose through a series of reactions to pyruvate and releases energy for the body in the form of ATP.

Q: Where does glycolysis occur?
A: In the cytoplasm of the cell.

Q: Is glycolysis aerobic or anaerobic?
A: Anaerobic. Glycolysis is the first step in both aerobic and anaerobic respiration.

Steps and Products

Q: What is the overall reaction of glycolysis?
A: Glucose + 2NAD+ + 2ADP + 2Pi → 2 Pyruvate + 2NADH + 2H+ + 2ATP + 2H2O

Q: How many enzymes catalyze the glycolytic pathway?
A: 10 enzymes

Q: What are the main products of glycolysis?
A: 2 pyruvate molecules, 2 NADH, and a net gain of 2 ATP

Energy Investment and Yield

Q: How many ATP molecules are used during glycolysis?
A: 2 ATP are used

Q: How many ATP molecules are produced during glycolysis?
A: 4 ATP are produced

Q: What is the net ATP yield of glycolysis?
A: Net gain of 2 ATP per glucose molecule

Key Processes

Q: What happens in the phosphorylation step of glycolysis?
A: Glucose (6C) is phosphorylated by 2 ATP to form fructose bisphosphate (6C)

Q: What occurs in the lysis step of glycolysis?
A: Fructose bisphosphate (6C) splits into two molecules of triose phosphate (3C)

Q: What happens in the oxidation step of glycolysis?
A: Hydrogen is removed from triose phosphate and transferred to NAD+ to form NADH

Final Steps

Q: What is the final product of glycolysis?
A: Pyruvate

Q: What can happen to pyruvate after glycolysis?
A: It can enter the next stage of respiration (Krebs Cycle/Citric Acid Cycle)

• Location:

  • Occurs in the cytoplasm of cells, not requiring any organelles.

• Oxygen requirement:

  • Anaerobic process - does not require oxygen.

• Input:

  • One glucose molecule (6-carbon sugar)

• Output:

  • Two pyruvate molecules (3-carbon compounds)

  • Net gain of 2 ATP molecules

  • 2 NADH molecules

Process overview:

• Consists of 10 enzyme-catalyzed reactions

• Divided into two phases: investment phase and payoff phase

Investment phase:

• Uses 2 ATP molecules to phosphorylate glucose

• Converts glucose to fructose-1,6-bisphosphate

Payoff phase:

• Splits fructose-1,6-bisphosphate into two 3-carbon compounds

• Generates 4 ATP and 2 NADH molecules

Role in respiration:

• Provides pyruvate for the citric acid cycle in aerobic respiration

• In anaerobic conditions, pyruvate can undergo fermentation

Regulation:

• Tightly controlled by allosteric enzymes

• Key regulatory enzymes: hexokinase, phosphofructokinase, and pyruvate kinase