An mRNA transcript of a T7 phage gene contains the base...

Key Concepts

Point Mutation

A point mutation is a type of genetic alteration where a single nucleotide base is changed, inserted, or deleted from a sequence of DNA or RNA. In this context, the change of a specific base—from G to A—is a substitution mutation that may alter the codon in an mRNA transcript, potentially leading to a change in the protein encoded by the gene.

Types of Mutation Effects

Mutations can have a range of effects on the protein product. A change in a single nucleotide might result in a silent mutation (where the amino acid remains unchanged due to codon redundancy), a missense mutation (where one amino acid is replaced by another), or a nonsense mutation (where the altered codon becomes a stop codon). Understanding these possibilities is crucial to predicting the impact of the mutation.

Codon Degeneracy

Codon degeneracy refers to the fact that multiple codons can encode the same amino acid. Because of this redundancy in the genetic code, a mutation in the mRNA that alters one nucleotide may not necessarily result in an altered amino acid. Recognizing this concept is key to determining whether a nucleotide substitution will alter protein structure or function.

Protein Translation

Protein translation is the process by which ribosomes synthesize proteins based on the sequence of codons in mRNA. Any alteration in the mRNA sequence due to a mutation can potentially affect the translation process, leading to changes in the structure and function of the resultant protein. Understanding this process is fundamental when evaluating the consequences of genetic mutations.

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