Science
Transcription and translation.
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 · 6 phases
Step by step.
- RNA polymerase binds to the promoter and transcribes DNA into pre-mRNA in the nucleus.
- Pre-mRNA is processed (capping, polyadenylation, splicing) into mature mRNA.
- Mature mRNA exits the nucleus and binds to a ribosome in the cytoplasm.
- tRNA molecules bring amino acids matching each mRNA codon via complementary anticodons.
- The ribosome moves along the mRNA, linking amino acids into a growing polypeptide chain.
- Translation stops when a stop codon is reached, and the completed protein is released and folded.
Examples
Real-world.
- 1 Insulin production: the insulin gene is transcribed and translated in pancreatic beta cells
- 2 Muscle cells expressing the actin and myosin genes to build contractile proteins
- 3 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.