Introduction to Biochemistry
Foundations, Scope, and Key Concepts
1. What Is Biochemistry?
| Aspect |
Description |
| Definition |
The study of the chemical processes and substances that occur within living organisms. |
| Core Focus |
Structure, function, and interaction of biomolecules (proteins, nucleic acids, lipids, carbohydrates). |
| Interdisciplinary Links |
Chemistry, molecular biology, genetics, physiology, pharmacology, and biotechnology. |
| Goal |
Explain how molecular-level events give rise to cellular functions, tissue behavior, and whole‑organism physiology. |
2. Historical Milestones
| Year / Period |
Milestone |
Significance |
| 1800s |
Discovery of cell theory (Schleiden, Schwann) |
Set the stage for studying life at the cellular level. |
| 1869 |
Friedrich Miescher isolates nuclein (DNA). |
First identification of a macromolecule that stores genetic information. |
| 1902 |
Eduard Buchner shows cell‑free fermentation. |
Demonstrates that enzymes (proteins) can catalyze reactions outside cells. |
| 1920s–30s |
Hans Krebs, Krebs cycle; Otto Warburg, glycolysis. |
Mapping of central metabolic pathways. |
| 1953 |
Watson & Crick reveal DNA double‑helix. |
Structural basis for genetic information storage. |
| 1958–60 |
Kendrew and Perutz solve protein structures (myoglobin, hemoglobin). |
Birth of structural biology. |
| 1970s–80s |
Development of recombinant DNA and PCR. |
Tools for manipulating and analyzing biomolecules. |
| 2000s |
Human Genome Project completed. |
Provides a complete reference of genetic information. |
| 2010s–present |
CRISPR‑Cas9, single‑cell omics, cryogenic EM. |
Precise genome editing and high‑resolution structural insights. |
3. Major Classes of Biomolecules
| Class |
Building Units |
Key Functions |
Representative Examples |
| Proteins |
Amino acids (20 standard) |
Catalysis (enzymes), signaling, transport, structural support, immunity |
Hemoglobin, DNA polymerase, antibodies |
| Nucleic Acids |
Nucleotides (A, T/U, G, C + sugar + phosphate) |
Genetic storage (DNA), information transfer (RNA), regulation |
DNA, mRNA, tRNA, rRNA |
| Carbohydrates |
Monosaccharides (glucose, fructose) |
Energy storage, structural components, cell‑cell recognition |
Glycogen, cellulose, glycoproteins |
| Lipids |
Fatty acids + glycerol or sterol backbone |
Membrane structure, energy storage, signaling molecules |
Phospholipids, triglycerides, cholesterol, steroid hormones |
4. Central Themes in Biochemistry
4.1. Structure ↔ Function
- Primary structure → amino‑acid sequence (proteins) or nucleotide sequence (DNA/RNA).
- Higher‑order structures (secondary, tertiary, quaternary) dictate activity.
- Conformational changes often regulate enzyme catalysis, signal transduction, and molecular recognition.
4.2. Enzyme Catalysis