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.

Verified step by step guidance

1. Understand the term 'null mutation': A null mutation is a type of mutation that results in the complete loss of function of the gene product. This means no functional protein is produced.
2. Review the mutation types provided: (1) promoter mutation, (2) splice site mutation, (3) missense mutation, (4) frameshift mutation, and (5) nonsense mutation. Consider how each type of mutation could lead to a null mutation.
3. Analyze nonsense mutations: A nonsense mutation introduces a premature stop codon in the coding sequence, leading to a truncated and likely nonfunctional protein. This can result in a null mutation.
4. Analyze frameshift mutations: A frameshift mutation alters the reading frame of the gene, often leading to a completely different and nonfunctional protein. This can also result in a null mutation.
5. Consider other mutation types: Promoter mutations and splice site mutations can disrupt gene expression or mRNA processing, potentially leading to no protein being produced. These could also result in a null mutation depending on the severity of the disruption.

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 resulting in 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 amino acids downstream of the mutation, often resulting in a nonfunctional protein. Frameshift mutations can also create premature stop codons, contributing to null mutations.