Transcription and translation

Science

Definition

The two-stage process of gene expression. Transcription copies a gene's DNA into mRNA in the nucleus, and translation uses that mRNA as instructions to build a protein at the ribosome in the cytoplasm. Together, they carry out the central dogma: DNA → RNA → Protein.

How It Works

  1. RNA polymerase binds to the promoter and transcribes DNA into pre-mRNA in the nucleus.
  2. Pre-mRNA is processed (capping, polyadenylation, splicing) into mature mRNA.
  3. Mature mRNA exits the nucleus and binds to a ribosome in the cytoplasm.
  4. tRNA molecules bring amino acids matching each mRNA codon via complementary anticodons.
  5. The ribosome moves along the mRNA, linking amino acids into a growing polypeptide chain.
  6. Translation stops when a stop codon is reached, and the completed protein is released and folded.

Examples

  • Insulin production: the insulin gene is transcribed and translated in pancreatic beta cells
  • Muscle cells expressing the actin and myosin genes to build contractile proteins
  • Antibiotics like tetracycline that kill bacteria by blocking their translation machinery
Key Fact

Central dogma: DNA → (transcription) → mRNA → (translation) → Protein. Each mRNA codon (3 bases) specifies one amino acid.

Related Terms

Transcription Translation Gene regulation Dna structure

Study This Concept

Practice transcription and translation with free review games in these units:

Biology Unit 4: DNA and Protein Synthesis