---
title: "Translation at the Ribosome"
description: "The ribosome reads codons and tRNA brings the matching amino acid, turning a base sequence into an amino acid sequence. The code is degenerate, non-overlapping and read from a fixed start."
canonical: https://lightmysky.com/learn/science/translation-at-the-ribosome-mt_1EdZzeqts1
source: https://lightmysky.com/learn/science/translation-at-the-ribosome-mt_1EdZzeqts1.md
retrieved: 2026-09-12
---

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# Translation at the Ribosome

The ribosome reads codons and tRNA brings the matching amino acid, turning a base sequence into an amino acid sequence. The code is degenerate, non-overlapping and read from a fixed start.

Subject: Science · Area: Genetics & Evolution · Ages 16 to 18
Page: https://lightmysky.com/learn/science/translation-at-the-ribosome-mt_1EdZzeqts1

## Ready when they can

- Matches a codon to its anticodon and says what the tRNA carries.
- Uses a codon table to build a short amino acid sequence from an mRNA sequence.
- Explains what degeneracy means for a change in the third base of a codon.

## Lesson: Reading codons, building proteins

Ribosomes read mRNA in groups of three bases called codons. Reading starts at AUG, which also brings the first amino acid, methionine. With four bases taken three at a time there are 64 codons for about 20 amino acids. Most amino acids therefore have several codons, and the difference often sits in the third base. That sharing is called degeneracy.

The ribosome is built from a small and a large subunit clamped around the mRNA. Transfer RNAs dock one codon at a time, each anticodon pairing with its codon. Every tRNA carries its amino acid, and the ribosome links each new arrival to the growing chain. Then the message slides along by exactly one codon.

**Example.** Try a short message: AUG followed by CUA, then a stop codon. AUG starts the chain with methionine, and CUA pairs with the anticodon GAU to add the next link. The stop codon fits no tRNA, so the finished chain is released to fold.

**Tip.** The reading frame is fixed from the start codon, and codons never overlap. Start one base off and every triplet after it changes, so always count in threes from AUG.

**Recap.** From AUG, triplet by triplet, tRNAs bring amino acids until a stop codon ends the chain.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Transcription and RNA Splicing in Eukaryotes](https://lightmysky.com/learn/science/transcription-and-rna-splicing-in-eukaryotes-mt_j2vc70vH5t)

## Opens up

- [Post-translational Modification and Protein Turnover](https://lightmysky.com/learn/science/post-translational-modification-and-protein-turnover-mt_93cxQwxxkh)
- [Gene Mutations and Their Consequences](https://lightmysky.com/learn/science/gene-mutations-and-their-consequences-mt_CDcaL6-iVp)
- [Transcription Factors and Epigenetic Control](https://lightmysky.com/learn/science/transcription-factors-and-epigenetic-control-mt_nF4JJ_EDa4)