Several types of mutation are identified and described in the chapter. These include (1) promoter mutation, (2) splice site mutation, (3) missense mutation, (4) frameshift mutation, and 5) nonsense mutation. Match the following mutation descriptions with the type(s) of mutations listed above. More than one mutation type might match a description.

A null mutation that does not produce any functional protein product.

Key Concepts

Nonsense Mutation

A nonsense mutation is a type of point mutation where a single nucleotide change results in a premature stop codon in the coding sequence of a gene. This leads to the production of a truncated protein that is usually nonfunctional, effectively creating a null mutation. Understanding this mutation is crucial for recognizing how genetic information can be disrupted, leading to loss of function.

Null Mutation

A null mutation refers to any mutation that results in the complete loss of function of a gene product. This can occur through various mechanisms, including nonsense mutations, frameshift mutations, or deletions that eliminate essential coding sequences. Recognizing null mutations is important for studying gene function and the effects of genetic disorders.

Frameshift Mutation

A frameshift mutation occurs when nucleotides are inserted or deleted from the DNA sequence, causing a shift in the reading frame of the genetic code. This alteration can lead to the production of entirely different and often nonfunctional proteins. Frameshift mutations can also result in premature stop codons, contributing to null mutations and further emphasizing their significance in genetic analysis.