Metabolism Overview and Principles

LECTURE 1:

Instructor: Setyana Mashaina, Faculty, Chemistry Biochemistry Department
Research Focus: RNA folding during transcription with some projects related to metabolism.
Objective: Understand the core concepts of metabolism essential for human survival.

Definition: Metabolism is the set of life-sustaining chemical reactions in organisms, including:
- Conversion of chemical compounds to generate energy (catabolism).
- Building up compounds to create cellular structures (anabolism).
Enzymes: Special proteins that catalyze biochemical reactions, making the interconversion of molecules more efficient.
Cellular Structure: Metabolism occurs in different cellular compartments (organelles) to increase efficiency and specialization.
Driving Forces: Reactions are driven by energetics (free energy, entropy, enthalpy) and the movement of enzymes.

Medical Relevance: Understanding metabolism is crucial for anyone pursuing a career in medicine, pharmaceuticals, or nutrition.
Health Applications: Knowledge of metabolism can help in understanding dietary effects and health conditions like diabetes.
- Example: Impact of different diets (e.g., Keto) and methods (e.g., intermittent fasting) on metabolism.
Pathophysiology Insights: Diseases such as cancer and metabolic disorders are linked to dysregulations in metabolic pathways.
- Example: Cancer cells primarily utilize glucose for energy and require extensive biosynthesis for rapid growth.

Autotrophs vs Heterotrophs:
- Autotrophs: Organisms that produce their own energy (e.g., plants, some bacteria).
- Heterotrophs: Organisms that consume others for energy (e.g., humans).
Energy and Oxygen Requirements:
- Organisms classified based on oxygen needs (aerobes and anaerobes).

Catabolism: The breakdown of complex molecules into simpler ones, releasing energy.
Anabolism: The synthesis of complex molecules from simpler ones, requiring energy.
- Important for growth and cellular repair.
Pathway Interconnections: Metabolic pathways are interconnected, and changes in one can affect others.

Enzymatic Functions:
- Catalyze reactions, reducing the activation energy required for metabolic processes.
- Enzymes are proteins that can perform specific chemistries with varying functionalities.
Cofactors and Coenzymes: Enzymes require additional substances (metal ions, vitamins) to function effectively.
- Examples include NAD (Nicotinamide adenine dinucleotide) used in electron transfer reactions.

Compartmentalization: Different metabolic processes occur in specific cellular compartments (e.g., mitochondria, cytosol).
Metabolite Transport: Understanding how metabolites move between compartments is essential for metabolic function.

Free Energy Changes:
- Exergonic: Reactions that release energy (negative ΔG).
- Endergonic: Reactions that require energy (positive ΔG).
Standard vs Physiological Free Energy:
- Standard conditions (laboratory settings) yield fixed ΔG measurements.
- Physiological conditions (in vivo) show variability in ΔG based on changing metabolite concentrations.

Regulatory Mechanisms: Control over metabolic pathways through various means:
- Feedback inhibition: End products inhibit enzymes early in the pathway to regulate flow.
- Increasing enzyme concentration through gene expression for long-term regulation.
Pathway Directionality Control: Requires distinct steps in catabolic and anabolic pathways to avoid reversing reactions directly.

Principles to Remember: Metabolism is a complex, efficient, and tightly regulated series of reactions essential for life. Understanding these concepts will be crucial for success in this course and future studies.