A section of a gene has the base sequence ATGTTTGGCAAA.
One base in this section changes, so the third triplet becomes GCC.
The table shows the amino acid coded for by each triplet.
Table
| Triplet of bases | Amino acid coded for |
|---|---|
| AAA | Lysine (Lys) |
| ATG | Methionine (Met) |
| GCC | Alanine (Ala) |
| GGC | Glycine (Gly) |
| TTT | Phenylalanine (Phe) |
What is the effect of this change on the protein made?
Every amino acid after the change is different in the protein.
The protein is one amino acid shorter than the original protein.
The protein is unchanged because only one base has been changed.
One amino acid in the protein is replaced by a different one.
184 exam-style questions on OCR GCSE Biology 1.2 What happens in cells (and what do cells need)?, covering 1.2.1 Structure of DNA, 1.2.2 Nucleotides and complementary bases, 1.2.3 Protein synthesis, 1.2.4 DNA structure and the proteins made, 1.2.5 Investigating enzymatic reactions, and 1.2.6 Mechanism of enzyme action. Each one has a worked solution and a mark scheme showing where the marks go.