# DNA, RNA, protein

> Every living thing stores its instructions in DNA, copies the part it needs into RNA, and reads that copy to build proteins.

Source: https://khushisingh.in/explore/01-dna-rna-protein/
Author: Khushi Singh (khushisingh.in). Licence: CC BY 4.0 for text and original illustrations, unless a credit says otherwise.
Evidence labels used on this site: established, strong evidence, emerging, hypothesis, debated. Where a page has Simple, Curious and Expert versions, all three follow.

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[Biology made simple](https://khushisingh.in/explore/) · How genes work · 1 of 8

About 2 minutes

A bacterium, an oak tree and a person all keep their instructions in **DNA**, written with four letters: A, T, G and C. A **gene** is a stretch of DNA that holds the recipe for one product, usually a protein. (evidence: established)

Cells first **copy** a gene into a working message, **mRNA** (*transcription*). A ribosome then **reads** the mRNA and joins amino acids in the order it spells (*translation*), and the chain folds into a protein that does a job. This flow, DNA → RNA → protein, is the *central dogma* (Crick 1970). Which genes a cell copies, and when, is what makes a leaf cell different from a root cell, or a nerve cell from a skin cell.

*[Here the web page has an interactive activity; open the source URL to use it.]*

*[Here the web page has an interactive 3D model; open the source URL to use it.]*

**In my research:** [How gene expression is controlled in early development →](https://khushisingh.in/research/interests/)

## Sources

1. Crick F (1970) Central dogma of molecular biology. Nature 227:561–563. [doi:10.1038/227561a0](https://doi.org/10.1038/227561a0)
2. Alberts B, et al. (2002) Molecular Biology of the Cell, 4th edition. Garland Science. Free on the NCBI Bookshelf. [link](https://www.ncbi.nlm.nih.gov/books/NBK21054/)