Anaerobic Metabolism: Glycolysis Quiz

Anaerobic Metabolism: Glycolysis

• Glycolysis is a metabolic pathway that converts glucose to pyruvate, occurring in the cytosol of all tissues.
• It involves 10 reactions, which can be grouped into 4 stages: activation, splitting, oxidation, and ATP synthesis.

Structure and Function of Glucose and Glycogen

• Glucose is a monosaccharide, an immediate energy source that can be synthesized from non-carbohydrate sources through gluconeogenesis.
• Glycogen is a polysaccharide, a medium-term fuel source with low osmolarity, synthesized and broken down in the liver.

Sources of Glucose for Glycolysis

• Glucose can come from dietary sugars and starch, breakdown of stored glycogen in the liver, or recycled glucose from lactic acid, amino acids, or glycerol.

Glycolysis Pathway

• The glycolysis pathway involves 10 reactions, starting with glucose and ending with pyruvate, and involves enzyme-catalyzed reactions.
• The pathway produces ATP, NADH, and pyruvate, which can be used for energy production or as intermediates for fat synthesis and amino acid synthesis.

ATP Synthesis

• ATP synthesis in glycolysis occurs through substrate-level phosphorylation, resulting in a net yield of 2 ATP per glucose molecule.
• The ATP yield from glycolysis is low, but pyruvate can enter the mitochondria for further ATP production.

Anaerobic Glycolysis

• In anaerobic conditions, pyruvate is converted to lactate to regenerate NAD+, allowing glycolysis to continue.
• Anaerobic glycolysis occurs in tissues with limited oxygen supply, such as skeletal muscle during intense exercise and red blood cells.

Regulation of Glycolysis

• Glycolysis is regulated through allosteric control and hormonal control, with phosphofructokinase being a key enzyme controlled by ATP, citrate, and AMP.
• Feedback inhibition of phosphofructokinase by ATP helps regulate glycolysis.

Specialised Functions in Tissues

• Glycolysis is the only energy-producing pathway in red blood cells, and is essential for ATP production during intense exercise in skeletal muscle.
• Glycolysis is also important in the brain, where it is a major source of ATP, as the brain cannot use fats as fuels.

The Warburg Effect

• Tumour cells preferentially generate energy through anaerobic glycolysis, even when mitochondria are intact, producing lactate at a rate 200 times that of healthy cells.
• The Warburg effect may be useful as a diagnostic tool and/or therapeutic target.

Key Points

• Glycolysis is a universal metabolic pathway that can occur in all tissues, producing ATP, NADH, and pyruvate.
• The pathway can function in aerobic or anaerobic conditions, with pyruvate being converted to lactate in anaerobic conditions.
• Glycolysis is regulated through allosteric control and hormonal control, and has specialized functions in certain tissues.

This quiz covers anaerobic metabolism, focusing on glycolysis, based on chapters 11 and 13 of the biochemistry and molecular biology textbook for 4MBBS101 course.