Full course notes — structured for quick reference and revision
MBC 111: Full Course Introduction
November 19, 2025
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1. Introduction to Biochemistry
Biochemistry is the study of chemical processes and molecules that occur inside living organisms. It explains how life works at the molecular level.
Branches of Biochemistry
- Structural biochemistry – studies biomolecules' structure.
- Metabolic biochemistry – focuses on metabolism (catabolism + anabolism).
- Molecular biology – studies DNA, RNA, and protein synthesis.
- Enzymology – study of enzymes and reaction mechanisms.
- Clinical biochemistry – chemical analysis of blood, urine, tissues.
Importance of Biochemistry
- Understanding diseases
- Drug development
- Nutrition & agriculture
- Forensics
- Biotechnology
- Genetic engineering
2. Biomolecules
Biomolecules are the chemical compounds that make up living cells. There are four major classes:
A. Carbohydrates
Main energy source.
Types:- Monosaccharides – glucose, fructose, galactose
- Disaccharides – sucrose, lactose, maltose
- Polysaccharides – starch, glycogen, cellulose
- Energy (ATP production)
- Structural roles (cellulose, chitin)
- Storage (starch, glycogen)
B. Proteins
Made of amino acids.
Levels of protein structure:- Primary – amino acid sequence
- Secondary – α-helix, β-sheet
- Tertiary – 3D folding
- Quaternary – multiple subunits (e.g., hemoglobin)
- Enzymes
- Hormones
- Transport (hemoglobin)
- Immunity (antibodies)
- Structure (keratin, collagen)
C. Lipids
Hydrophobic molecules.
Types:- Fatty acids
- Triglycerides
- Phospholipids
- Steroids (cholesterol)
- Long-term energy
- Cell membrane structure
- Insulation
- Precursor for hormones
D. Nucleic Acids
Genetic information molecules.
- DNA – hereditary material
- RNA – protein synthesis
- Pentose sugar
- Phosphate
- Nitrogenous bases (A, T/U, G, C)
3. Water and pH
Water as a Biological Solvent
- High heat capacity
- Good solvent
- Cohesive and adhesive
- High surface tension
Acids, Bases and Buffers
pH measures hydrogen ion concentration. Buffers resist pH changes (e.g., bicarbonate buffer in blood).
Typical biological pH is 7.35–7.45.
4. Enzymes
Enzymes are biological catalysts that speed up reactions.
Characteristics
- Highly specific
- Not consumed in reactions
- Work best at optimal pH and temperature
- Affected by inhibitors
Types of Enzyme Inhibition
- Competitive (competes with substrate)
- Non-competitive (binds on another site)
Enzyme Kinetics
Vmax – maximum velocity
Km – affinity for substrate (Low Km = high affinity).
5. Energy & Metabolism
Metabolism = sum of all chemical reactions.
- Catabolism – breaking down (releases energy)
- Anabolism – building molecules (requires energy)
ATP
Main energy currency of the cell. Produced in:
- Glycolysis
- Krebs cycle
- Electron transport chain
6. Carbohydrate Metabolism (Simple Overview)
Glycolysis
Breakdown of glucose → pyruvate. Occurs in cytoplasm. Produces 2 ATP + 2 NADH.
Krebs Cycle
Occurs in mitochondria. Produces NADH, FADH₂, ATP.
Electron Transport Chain
Produces ~34 ATP. Requires oxygen.
7. Protein & Amino Acid Metabolism
- Transamination
- Deamination
- Urea cycle (removes toxic ammonia)
Proteins can be used for energy when carbohydrates are low.
8. Lipid Metabolism
- β-oxidation — Breakdown of fatty acids → acetyl-CoA + energy.
- Lipid synthesis — Occurs mainly in the liver.
9. Nucleic Acid Metabolism
DNA replication
Semi-conservative. Enzymes: helicase, DNA polymerase, ligase.
Transcription & Translation
Transcription: DNA → mRNA. Translation: mRNA → protein (ribosomes).
10. Vitamins & Cofactors
Vitamins function as coenzymes.
Examples- Vitamin C – collagen synthesis
- B-complex – enzyme cofactors
- Vitamin D – calcium absorption
- Vitamin K – blood clotting
Deficiencies cause diseases (scurvy, rickets, pellagra).
11. Hormones & Signaling
Biochemistry of insulin, glucagon, steroid hormones, neurotransmitters. Cells communicate through chemical signals.
12. Laboratory Techniques in Biochemistry
Used in MBC 111 practicals:
- Spectrophotometry
- Chromatography
- Electrophoresis
- Centrifugation
- Titration
- Microscopy
13. Applications of Biochemistry
- Diagnostics (blood tests)
- Treatment of diseases
- Nutrition & food science
- Agriculture & animal science
- Forensic science
- Biotechnology (GMOs, vaccines)