Researchers study a gene that codes for an enzyme. Each letter in the amino acid column represents a different amino acid.
| DNA triplet | Amino acid |
|---|---|
| TAC | P |
| TAT | P |
| GGT | Q |
| GAT | R |
| AAA | S |
| AAG | S |
| CCT | L |
| GAA | U |
| GTA | V |
| AAC | W |
| CTG | X |
| AAT | Y |
The table shows the first five complete triplets read from the start of the sequence for the original gene and three variants.
| Gene | DNA sequence |
|---|---|
| Original | TAC GGT AAA CCT GAA |
| Variant 1 | TAT GGT AAG CCT GAA |
| Variant 2 | TAC GAT AAA CCT GAA |
| Variant 3 | TAC GTA AAC CTG AAT |
Variant 3 was caused by the deletion of one base near the start of the sequence. All three variants produce the same amount of protein.
Explain which variant is most likely to have the lowest enzyme activity. Include why this prediction is not certain.
62 exam-style questions on AQA GCSE Biology 6.1 Reproduction, covering 6.1.1 Sexual and asexual reproduction, 6.1.2 Meiosis, 6.1.3 Advantages and disadvantages of sexual and asexual reproduction, 6.1.4 DNA and the genome, 6.1.5 DNA structure, 6.1.6 Genetic inheritance, 6.1.7 Inherited disorders, and 6.1.8 Sex determination. Each one has a worked solution and a mark scheme showing where the marks go.