A fragment of a wild-type polypeptide is sequenced for seven amino acids. The same polypeptide region is sequenced in four mutants. Wild-type polypeptide N . . . Thr–His–Ser–Gly–Leu–Lys–Ala . . . C Mutant 1 N . . . Thr–His–Ser–Val–Leu–Lys–Ala . . . C Mutant 2 N . . . Thr–His–Ser–C Mutant 3 N . . . Thr–Thr–Leu–Asp–C Mutant 4 N . . . Thr–Gln–Leu–Trp–Ile–Glu–Gly . . . Use the available information to characterize each mutant.

Key Concepts

Amino Acid Sequence

The amino acid sequence of a polypeptide is the specific order of amino acids that make up the protein. This sequence determines the protein's structure and function. In the context of the question, comparing the wild-type sequence with those of the mutants helps identify specific mutations that may affect the protein's properties.

Mutations

Mutations are changes in the nucleotide sequence of DNA that can lead to alterations in the amino acid sequence of proteins. These changes can be classified as missense, nonsense, or silent mutations, depending on their effects on the resulting polypeptide. Analyzing the differences between the wild-type and mutant sequences allows for the characterization of each mutant's genetic alteration.

Phenotypic Effects of Mutations

The phenotypic effects of mutations refer to the observable traits or characteristics that result from genetic changes. Mutations can lead to variations in protein function, which may manifest as changes in phenotype. Understanding how each mutant's amino acid sequence differs from the wild-type can provide insights into potential functional consequences and the biological significance of these mutations.