# [SCI] Molecular Biology & Biochemistry

**Molecular Biology** is the study of biological processes at the molecular level — DNA, RNA, proteins, and the mechanisms of gene expression — founded in the 1940s–1950s at the intersection of physics, chemistry, and biology.

## Overview

Schrödinger's *What is Life?* (1944) proposed that genes must be aperiodic crystals storing information, inspiring physicists (Crick, Wilkins) to enter biology. Chargaff's rules (1950) showed base pairing in DNA. Franklin's X-ray diffraction (1952) revealed the helical structure. Watson and Crick's double helix model (1953) showed how genetic information is stored and copied. Crick's Central Dogma (1958) described the information flow: DNA → RNA → Protein. The genetic code was cracked (1961–1965). PCR (Mullis 1983) allowed amplification of specific DNA sequences, democratising molecular biology.

Biochemistry — the chemistry of living systems — developed in parallel, elucidating metabolic pathways (Krebs cycle 1937, ATP synthesis), enzyme kinetics, and membrane transport.

## Key Figures & Recognition

- **James Watson** (1928–) & **Francis Crick** (1916–2004): DNA double helix. **Nobel Prize 1962** (shared with Wilkins; Franklin died 1958).
- **Rosalind Franklin** (1920–1958): X-ray diffraction of DNA. No Nobel (died before award; widely considered an injustice).
- **Frederick Sanger** (1918–2013): Protein sequencing (Nobel 1958) and DNA sequencing (Nobel 1980) — two separate prizes.
- **Kary Mullis** (1944–2019): PCR. **Nobel Prize 1993**.

## Seminal Papers

- Watson, J. & Crick, F. "A Structure for Deoxyribose Nucleic Acid." *Nature* 171 (1953).
- Crick, F. "On Protein Synthesis." *Symp. Soc. Exp. Biol.* 12 (1958) — Central Dogma.
- [Sanger, F. et al. "DNA sequencing with chain-terminating inhibitors." *PNAS* 74 (1977)](https://doi.org/10.1073/pnas.74.12.5463)

## What This Enables

- **[SCI] Genomics & Computational Biology** — Genomics is molecular biology applied at genome scale: sequencing, assembly, and annotation extend molecular biology methods.

## Discovery Character
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**Surprise level**: High — The discovery that the biological blueprint is a digital code stored in a linear sequence of four bases — and that it operates via a simple copying mechanism — was surprising in its elegance and simplicity. That physics and chemistry could fully explain the basis of life and heredity was not accepted until the 1950s.
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**Mode**: Systematic with competitive pressure and ethical shadow. Watson and Crick used model-building, Chargaff's base-pairing rules, and Franklin's X-ray data in a systematic race against Pauling. Franklin's Photo 51 was shown to Watson by Wilkins without her knowledge — the ethical complexity surrounds what was scientifically systematic. Crick and Watson's key insight (antiparallel strands, base-pairing) was a creative leap that clicked into place when they saw the right model.
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# Parents

* [SCI] Quantum Mechanics
* [SCI] Quantum Mechanics
* [TECH] Chemical Industry