Translation
| English | Chinese | Pinyin |
|---|---|---|
| translation | 翻译 | fān yì |
| codon | 密码子 | mì mǎ zi |
| transfer RNA | 转运RNA | zhuǎn yùn RNA |
| anticodon | 反密码子 | fǎn mì mǎ zi |
Reading the message into a protein
- The mRNA carries the gene's message out to the cytoplasm.
- There, that message must be turned into an actual protein.
- The four-letter RNA code is read and rewritten as a chain of amino acids.
- This decoding step is called translation.
Codons: reading in threes
- Translation 翻译 reads the mRNA three bases at a time.
- Each group of three bases is a codon 密码子.
- Every codon stands for one amino acid.
- So the order of codons sets the order of amino acids in the protein.
Translation builds a protein by reading…
Translation reads the mRNA message and builds the matching chain of amino acids — a protein.
How many mRNA bases make up one codon?
A codon is three bases, and each codon codes for one amino acid.
The ribosome and tRNA
- A ribosome clamps onto the mRNA and moves along it.
- Transfer RNA 转运RNA molecules, called tRNA, bring the amino acids.
- Each tRNA has an anticodon 反密码子 that pairs with a matching codon.
- This ensures the right amino acid arrives at the right spot.
Translation at the ribosome
Step through translation - the ribosome reads mRNA in codons and tRNA brings the matching amino acids.
The molecule that carries an amino acid to the ribosome is called ____ RNA.
Transfer RNA (tRNA) carries an amino acid and has an anticodon that matches the mRNA codon.
A tRNA's anticodon pairs with the matching codon on the mRNA.
The anticodon base-pairs with the codon, so the right amino acid is added in the right place.
Building the chain
- As the ribosome reads each codon, the matching amino acid is added.
- The growing chain gets one link longer for every codon.
- A special "stop" codon signals the end of the protein.
- The finished chain then folds into a working protein.
Select all true statements about translation.
Copying DNA into mRNA is transcription, not translation. The other three are correct.
The code is read in triplets: three bases make one codon, one codon makes one amino acid. Read them out of step — starting one base early or late — and every codon after is wrong. The reading frame must line up exactly.
From codon to amino acid:
- The mRNA codon $\text{A–U–G}$ codes for the amino acid methionine — and also says "start".
- The next codon adds the next amino acid, and so on.
- A stop codon (like $\text{U–A–A}$) has no amino acid; it ends the chain.
Translation builds a protein from mRNA. The ribosome reads the mRNA in codons (groups of three bases), and transfer RNA (tRNA) brings each amino acid, its anticodon pairing with the codon. Amino acids join in order until a stop codon ends the protein.