Biology / Unit 6: DNA and Protein Synthesis
6.4 Translation and the Genetic Code
Notes
Translation turns the mRNA code into a chain of amino acids (a protein). It happens at ribosomes.
- mRNA is read in groups of three bases called codons. Each codon codes for one amino acid.
- AUG is the start codon (codes for methionine). Stop codons (UAA, UAG, UGA) end translation.
- tRNA has an anticodon that pairs with the codon and carries the matching amino acid.
- Amino acids are linked by peptide bonds to form a polypeptide.
- The code is nearly universal: the same codons mean the same amino acids in almost all organisms.
Practice
How many bases make up one codon?
Codons are triplets of mRNA bases.
An mRNA codon is GCU. What is the tRNA anticodon?
Anticodons are complementary: G-C, C-G, U-A.
An mRNA has 30 bases between the start codon and the stop codon, not counting either. How many amino acids do those 30 bases code for?
30 bases divided by 3 bases per codon equals 10 codons.
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