The Table shows some mRNA codons and the amino acids they code for.
In mRNA, the base U replaces the base T.
Table
| mRNA codon | Amino acid |
|---|---|
| AUG | methionine |
| GCU | alanine |
| UUC | phenylalanine |
| GGA | glycine |
| CAU | histidine |
| UGG | tryptophan |
A section of mRNA has the base sequence AUG GCU UUC GGA.
Use the Table to give the sequence of amino acids coded for by this mRNA.
Give the sequence of bases on the DNA strand that was used to make this section of mRNA.
A protein contains 150 amino acids.
Calculate the number of bases in the mRNA that code for this protein.
There are 20 different amino acids in proteins.
Explain why each amino acid must be coded for by three bases and not by one base.
44 exam-style questions on Edexcel GCSE Biology 3.2 DNA and protein synthesis, covering 3.2.1 DNA structure as a polymer, 3.2.2 Genome and gene definitions, 3.2.3 Extracting DNA from fruit, 3.2.4 Base order determines protein shape, 3.2.5 Stages of protein synthesis, 3.2.6 Non-coding DNA variants affecting phenotype, and 3.2.7 Coding DNA variants affecting phenotype. Each one has a worked solution and a mark scheme showing where the marks go.