What Is DNA
Last updated: March 31, 2026
Key Facts
- Human DNA has ~3 billion base pairs and 20,000-25,000 genes
- Uncoiled DNA from one cell stretches about 2 meters
- Humans share 99.9% DNA with each other and ~60% with bananas
- Structure discovered by Watson and Crick in 1953, with crucial work by Rosalind Franklin
- Only 1-2% of DNA codes for proteins
Structure
A twisted ladder: sugar-phosphate sides, base-pair rungs. A-T and G-C base pairing allows accurate copying.
How DNA Works
Genes are DNA segments coding for proteins:
- Transcription: Gene copied into mRNA in the nucleus
- Translation: Ribosomes read mRNA and assemble proteins
Central Dogma: DNA → RNA → Protein
DNA Replication
Before cell division, the helix unzips. Each strand templates a new complementary strand. DNA polymerases copy with ~1 error per billion base pairs.
Applications
- Forensics: DNA fingerprinting identifies individuals
- Medicine: Genetic testing, gene therapy
- Ancestry: Trace ethnic background
- Agriculture: GMO crops
Related Questions
How is DNA different from RNA?
DNA is double-stranded with thymine. RNA is single-stranded with uracil. DNA stores info long-term; RNA carries temporary copies for protein building.
What is RNA and how is it different from DNA?
RNA (Ribonucleic Acid) is similar to DNA but has important differences: it's single-stranded, contains ribose sugar instead of deoxyribose, and uses uracil instead of thymine. RNA's primary role is translating genetic information into proteins, while DNA stores genetic information.
What is a chromosome?
A chromosome is a structure containing DNA and proteins found in cell nuclei. Human cells have 46 chromosomes (23 pairs). Chromosomes organize and protect DNA while enabling cell division. Each chromosome contains many genes.
How does DNA testing work?
DNA testing analyzes specific DNA sequences to identify genetic markers, ancestry information, disease risks, or family relationships. Tests examine segments of DNA and compare them to databases. Results reveal genetic information about heritage, health predispositions, and biological relationships.
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Sources
- Wikipedia — DNACC-BY-SA-4.0
- MedlinePlus — DNApublic_domain