Lecture 2, intro to biochemistry, met week 1

Introduction to Biochemistry

  • Institution: Queen Mary University of London, Malta Campus

  • Instructor: Dr. Robert Formosa

Topics to be Covered

  • Clinical Relevance of Biochemistry

  • What is Biochemistry?

  • Nutrition: The Starting Point

  • Drivers of Metabolism: Enzymes

  • Complex Metabolic Pathways

  • Linked Metabolic Pathways

  • Tightly-Controlled Metabolic Pathways

Clinical Relevance of Biochemistry

  • Biochemical origins: Most diseases have biochemical origins or alterations caused by disease processes.

Understanding Biochemistry

  • Definition: Biochemistry is the branch of science that examines chemical processes within and related to living organisms.

  • Occurs at the cellular and molecular levels, impacting all bodily systems and organs.

  • Focuses on the reactions and changes to chemicals within the body.

Nutrition: The Foundation

  • Slogan: "You are what you eat!"

Key Nutrients:

  • Carbohydrates, Proteins, Fats

Metabolic Processes:

  • Glycogenesis, Glycogenolysis, Gluconeogenesis

  • Glucolysis, Lipogenesis, Amino Acid Metabolism

Types of Chemical Reactions

Anabolic Reactions

  • Build molecules and require energy (use ATP)

  • Non-spontaneous; moves away from equilibrium

  • Examples: Amino acids to proteins, glucose to glycogen, fatty acids to lipids.

Catabolic Reactions

  • Break down molecules and release energy (generate ATP)

  • Spontaneous; moves toward equilibrium

  • Examples: Proteins to amino acids, glucose to pyruvate, fat burning for weight loss.

General Metabolic Pathways

Catabolic Pathways

  • Breakdown of carbohydrates, fats, proteins into energy.

Anabolic Pathways

  • Synthesis of fats, proteins, nucleic acids from substrates.

Metabolic Pathways - Complexity

  • Involves multi-step processes and numerous intermediate products.

  • Example: Glucose metabolism involves various metabolic pathways, all linked.

Example of Metabolic Pathway: Glycolysis

  • Converts glucose to pyruvate through 10 distinct steps providing metabolic control, versatility, and interlinking with other pathways.

Regulation in Metabolic Pathways

Importance of Regulation

  • Maintains homeostasis within the body by managing metabolic responses based on nutrient availability and hormonal signals.

Mechanisms of Regulation

  1. Compartmentalization

    • Specialization of organ and cellular components to control different aspects of metabolic pathways.

  2. Enzyme Control

    • Key enzymes regulate the flow of metabolites through pathways.

    • Rate-limiting enzymes often have low activity and are located near the start of pathways.

Examples of Enzyme Mechanisms

  • Allostery: Short term regulation of enzyme activity.

  • Covalent Modification: Addition of phosphate groups can modulate enzyme activity.

  • Protein Synthesis/Degradation: Long-term regulation through synthesis and degradation rates of enzymes.

Key Enzyme Functions

  • Kinases: Add phosphate groups (e.g., creatine kinase)

  • Phosphorylases: Move phosphates from one molecule to another.

  • Phosphatases: Remove phosphate groups through hydrolysis.

  • Dehydrogenases: Transfer hydrogen ions between molecules.