Metabolism study guide

Overview of Metabolism

• Metabolism: Totality of chemical reactions in the body, including:
  • Anabolism: Building up molecules (e.g., protein synthesis).
  • Catabolism: Breaking down molecules (e.g., cellular respiration).

Cellular Respiration

• Cellular Respiration: Process by which cells produce ATP.
  • Steps Involved:
  • Glycolysis: Breakdown of glucose.
  • Citric Acid Cycle: Further oxidation of products from glycolysis.
  • Oxidative Phosphorylation: Production of ATP using energy from electrons.
  • Usable energy in ATP: Contained in high-energy phosphate bonds.

Oxidation and Reduction

• Oxidation: Loss of electrons.
• Reduction: Gain of electrons.
• Importance in metabolism:
  • Integral for transferring energy and electrons during metabolic reactions.
• Coenzymes involve in these reactions include:
  • NAD+: Electron carrier in metabolic reactions.
  • FAD: Another electron carrier.

Phosphorylation Mechanisms

• ADP to ATP conversion:
  • Substrate-level Phosphorylation: Direct transfer of a phosphate group.
  • Oxidative Phosphorylation: Indirect method involving the electron transport chain.

Glycolysis

• Starting Material: Glucose.
• Products of Glycolysis:
  • Pyruvic Acid: Can become lactic acid or enter the citric acid cycle.
  • ATP: Energy currency of the cell.
  • NADH: Electron carrier.
  • FADH2: Another electron carrier.
• Oxygen Requirement: Glycolysis does not require oxygen (anaerobic pathway).

Pyruvic Acid and the Citric Acid Cycle

• Before entering Citric Acid Cycle: Pyruvic acid is converted to Acetyl CoA.
• Key Events of Citric Acid Cycle:
  • Starting Material: Acetyl CoA.
  • Products of 1 Turn:
  • Citric acid.
  • Keto acids.
  • CO2 (waste product).
  • NADH.
  • FADH2.
  • ATP.
• Oxygen Requirement: Does require oxygen indirectly but not as a reactant.

Electron Transport Chain

• Outcome: Formation of proton gradient used to synthesize ATP via ATP synthase.
• Final Electron Acceptor: Oxygen, combining with electrons to form water, crucial for survival.

ATP Yield

• Aerobic Respiration Output: Maximum of approximately 36-38 ATP per glucose molecule.
• Comparison with Anaerobic Respiration: Less efficient (2 ATP via fermentation).

Blood Glucose Regulation

• Mechanisms to regulate blood glucose levels include:
  • Glycogenesis: Formation of glycogen.
  • Glycogenolysis: Breakdown of glycogen.
  • Gluconeogenesis: Formation of glucose from non-carbohydrate sources.

Fatty Acid Oxidation

• Oxidation of Fatty Acids: Process to enter cellular respiration pathway, generating energy.
• Entry Point: Fatty acids converted to Acetyl CoA through Beta Oxidation.

Lipid Metabolism

• Lipogenesis: Synthesis of fats.
• Lipolysis: Breakdown of fats.
• Ketogenesis/Ketone Bodies: The production of ketones from fatty acids when glucose is low.

Amino Acid Metabolism

• Degradation of Amino Acids:
  • Involves Transamination: Transfer of amino groups.
  • Produces keto acids, glutamic acid, ammonia (waste), and urea.
• Protein Synthesis: Building of proteins based on genetic code support metabolic functions.