A gene encodes a protein with the following amino acid...

A gene encodes a protein with the following amino acid sequence: Met-Lys-Ser-Pro-Ala-Thr-Pro A nonsense mutation from a single-base-pair substitution occurs in this gene, resulting in a protein with the amino acid sequence Met-Lys. An intergenic suppressor mutation allows the gene to produce the full-length protein. With the original mutation and the intergenic suppressor present, the gene now produces a protein with the following amino acid sequence: Met-Lys-Cys-Pro-Ala-Thr-Pro Give the location and nature of the original mutation and of the intergenic suppressor.

A gene encodes a protein with the following amino acid sequence:
Met-Lys-Ser-Pro-Ala-Thr-Pro
A nonsense mutation from a single-base-pair substitution occurs in this gene, resulting in a protein with the amino acid sequence Met-Lys. An intergenic suppressor mutation allows the gene to produce the full-length protein. With the original mutation and the intergenic suppressor present, the gene now produces a protein with the following amino acid sequence:
Met-Lys-Cys-Pro-Ala-Thr-Pro
Give the location and nature of the original mutation and of the intergenic suppressor.

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Key Concepts

tRNA Recognition and Suppressor tRNA

The fidelity of translation is maintained by precise codon-anticodon pairing, where tRNAs deliver specific amino acids to the ribosome. A suppressor tRNA, which arises from an intergenic suppressor mutation, has an altered anticodon that can recognize what would normally be a stop codon. Consequently, it inserts an amino acid at that position, allowing protein synthesis to continue despite the presence of a premature stop codon.

Nonsense Mutation

A nonsense mutation is a point mutation where a single base substitution converts a normal codon into a premature stop codon. This premature stop leads to the early termination of translation, resulting in a truncated and typically nonfunctional protein.

Intergenic Suppressor Mutation

An intergenic suppressor mutation occurs in a different gene than the original mutation. In scenarios like this, the mutation often affects a tRNA gene, altering its anticodon so that it can recognize a stop codon and insert an amino acid during translation. This suppression allows the ribosome to bypass the premature stop signal, restoring the production of a full-length protein.

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