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From DNA to mRNA

Transcription makes mRNA from a DNA template strand. RNA polymerase reads the template, and the bases are paired over. A in DNA becomes U in RNA, T becomes A, C becomes G and G becomes C. Thymine is not found in RNA. The mRNA is then read in groups of three, the codons. A template of six bases gives two codons and can become two amino acids if neither is a stop. In eukaryotes transcription happens in the nucleus, and introns are spliced out before the mRNA goes to the ribosome. Not every gene is on in every cell. That is gene regulation.

\mathrm{A}\to\mathrm{U},\ \mathrm{T}\to\mathrm{A},\ \mathrm{C}\to\mathrm{G},\ \mathrm{G}\to\mathrm{C}

from DNA template to mRNA

Symbols

$template$	the DNA strand that is read
$codon$	three bases

Example

The template TAC GGA is 6 bases.

Codons: $6/3 = 2$ , and the mRNA becomes AUG CCU, methionine and proline.

Check the direction. It is the template strand you transcribe, not the other DNA strand.

Practise from gene to protein for free →

← From amino acids to bases · PCR →

Part of Biology 2: From gene to protein.