Glycolysis and Cellular Respiration

What is the most important regulator of glycolysis?

How many ATP molecules are produced from glycolysis in red blood cells?

What molecule do two pyruvate molecules get converted into during oxidative decarboxylation?

What is the energy yield from the oxidation of one molecule of NADH?

What is the primary function of glycolysis?

What is the primary function of the citric acid cycle?

Where does glycolysis take place within the cell?

How much ATP is produced from the oxidation of two molecules of acetyl CoA in the citric acid cycle?

Which of the following enzymes is involved in the first step of glycolysis?

Which component is primarily responsible for the anabolic functions within the citric acid cycle?

Which organ is primarily dependent on glycolysis for energy due to the lack of mitochondria?

Which of the following is NOT a product of the citric acid cycle?

What occurs during the first phase of glycolysis?

What is the main product of glycolysis under aerobic conditions?

Which of the following statements about the citric acid cycle (Krebs cycle) is true?

Which pathway for glucose oxidation does NOT produce energy?

Glycolysis

Definition: The breakdown of glucose to pyruvate or lactate.
Site: Cytoplasm of every cell.
Key Enzymes:
- Glucokinase (liver) and Hexokinase (other tissues)
- Phosphofructokinase (rate limiting step)
- Pyruvate kinase
Medical Importance:
- Essential for energy production in all cells.
- Particularly important in red blood cells, skeletal muscles during exercise, testes, and leukocytes.

Hormonal Regulation of Glycolysis

Insulin: Stimulates glycolysis by enhancing the activity of key enzymes like hexokinase and phosphofructokinase.
Glucagon: Inhibits glycolysis by reducing the activity of key enzymes.

Oxidative Decarboxylation of Pyruvate

Definition: The conversion of pyruvate to acetyl CoA.
Site: Mitochondria
Key Enzyme: Pyruvate Dehydrogenase Complex (PDH)
Products: Acetyl CoA, NADH

Citric Acid Cycle (Krebs Cycle)

Definition: A series of reactions that oxidize acetyl CoA to CO2, water, and energy.
Site: Mitochondria
State: Aerobic (presence of oxygen)
Key Steps:
- Acetyl CoA condenses with oxaloacetate to form citrate.
- Citrate is converts back to oxaloacetate at the end of the cycle.
Energy Yield:
- One acetyl CoA produces 10 ATP.
- Two acetyl CoA produce 20 ATP.

Biomedical Importance of the Citric Acid Cycle

Amphibolic: Has both anabolic and catabolic functions.
Anabolic Functions:
- Synthesis of fatty acids (from citrate)
- Synthesis of ketone bodies and cholesterol (from acetyl CoA)
- Synthesis of glucose (gluconeogenesis)
- Synthesis of non-essential amino acids:
  - Pyruvate → alanine
  - Oxaloacetate → aspartate
  - α-ketoglutarate → glutamate
- Synthesis of heme (from succinyl CoA and glycine)

Test your knowledge on glycolysis, including its key steps, regulation by hormones, and the conversion of pyruvate to acetyl CoA. This quiz also covers the importance of glycolysis in various tissues and its role in cellular energy production.