Chapter 5: Metabolism and Enzymes

Introduction

Metabolism involves chemical reactions that maintain life in cells.
Two types of metabolism:
- Catabolism: Breakdown of large molecules into smaller molecules (e.g., proteins into amino acids).
- Anabolism: Formation of large molecules from smaller ones (e.g., amino acids joining to form proteins).

Enzymes are proteins that catalyze metabolic reactions.
They speed up reactions by lowering activation energy required.
Monomer: Amino acids.
Nomenclature: Two groups based on naming:
- Substrate name + 'ase' (e.g., sucrase for sucrose).
- Functional group or reaction type (e.g., protease).

All enzymes are proteins.
Specificity: Each enzyme only catalyzes one type of reaction (e.g., maltase only breaks maltose).
Enzymes remain unchanged after reactions.
Enzymes are larger than their substrates.
Sensitive to temperature:
- Optimal body temperature (37°C) is where enzymes work best.
- Lower temperatures result in slower reactions due to less active enzymes.
- Each 10°C rise in temperature doubles the reaction rate (up to optimal temperature).
- Above 60°C, enzymes may become denatured (lose structure and function).
Sensitive to pH:
- Different enzymes work best at specific pH levels.
- Pepsin: Optimal in acidic conditions (pH 1-3, stomach).
- Amylase: Optimal in neutral conditions (pH 7, mouth).
- Trypsin: Optimal in slightly alkaline conditions (pH 8-9, small intestine).

The chapter highlights the distinction between catabolism and anabolism.
Enzymes are crucial for metabolic reactions due to their catalytic functions and specific operating conditions (temperature and pH).
Key identification and nomenclature of enzymes are based on substrate specificity and reaction type.

Refer to lecture notes and have one reliable reference book.
Mark critical points in notes (e.g., enzyme characteristics, optimal conditions).
Understand the concepts rather than rote memorization.

Next video will cover more on enzymes.