Biochemistry: Acetyl CoA, Glycolysis, and TCA Cycle

Acetyl CoA

• Acetyl CoA is a crucial molecule in intermediary metabolism, acting as a central hub for various pathways.
• It's derived from the breakdown of carbohydrates, fatty acids, and amino acids.
• Acetyl CoA enters the citric acid cycle for energy production or is used for fatty acid synthesis.
• The formation of Acetyl CoA is a key step, linking various metabolic pathways.

Glycolysis

• Glycolysis is the initial breakdown of glucose to pyruvate.
• It occurs in the cytoplasm of cells.
• It's a crucial metabolic pathway for energy production; producing ATP, NADH, and the precursor pyruvate.
• Glycolysis involves a series of 10 enzymatic reactions.
• Glycolysis can be either aerobic (in presence of oxygen) or anaerobic (absence of oxygen).
• The end product pyruvate can be further processed through aerobic respiration or fermentation depending on the presence of oxygen.

Citric Acid Cycle (TCA Cycle)

• The citric acid cycle is also known as the Krebs cycle.
• It's a crucial part of aerobic respiration, occurring in the mitochondrial matrix.
• It fully oxidizes Acetyl CoA, releasing carbon dioxide and generating high-energy electron carriers NADH and FADH2.
• The cycle involves a series of eight enzymatic reactions, ultimately regenerating oxaloacetate, allowing the cycle to continue.
• Key intermediates in the cycle are involved in the biosynthesis of various molecules.

Fatty Acid Synthesis

• Fatty acid synthesis involves the creation of long-chain fatty acids from acetyl CoA.
• This process typically occurs in the cytoplasm of cells.
• It's a reductive process, requiring NADPH.
• Fatty acid synthesis is crucial for building cell membranes and energy storage in the form of triglycerides.

Ketogenesis

• Ketogenesis is the production of ketone bodies from acetyl CoA.
• It occurs primarily in the liver when there's a limited supply of glucose.
• Ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) can be used as an alternative energy source by other tissues, particularly the brain, during prolonged fasting and starvation.
• This adaptation allows for the continued supply of energy when glucose is unavailable.

Energy Production

• Energy production in metabolic pathways involves the breakdown of fuels (carbohydrates, fats, and proteins) to generate ATP.
• ATP is the primary energy currency of the cell.
• Glycolysis, the citric acid cycle, and oxidative phosphorylation (the electron transport chain and chemiosmosis) are involved in this process.
• Oxidative phosphorylation, using the energy from NADH and FADH2, is the major pathway for ATP production.
• Efficient energy production is essential for cell function and survival.
• The overall process of energy production is tightly regulated by cellular needs and hormones.

Test your knowledge on key biochemical pathways including Acetyl CoA formation, glycolysis, and the citric acid cycle. Explore how these processes contribute to energy production and metabolic functions in cells. This quiz covers essential concepts in intermediary metabolism essential for understanding biochemistry.