Frameshift mutation

Definition

A frameshift mutation is a genetic alteration that occurs when nucleotides are added to or deleted from the DNA sequence in a number that is not a multiple of three, disrupting the reading frame of the genetic code. This type of mutation leads to a completely different translation from the original, often resulting in significant changes to the protein produced. Such mutations can have severe consequences for an organism's phenotype and may play a role in various diseases.

5 Must Know Facts For Your Next Test

1. Frameshift mutations can lead to premature stop codons, resulting in truncated proteins that are usually nonfunctional.
2. These mutations are often caused by errors during DNA replication or repair processes, as well as environmental factors such as radiation or certain chemicals.
3. The effects of frameshift mutations can be more severe than point mutations because they alter all downstream amino acids in the protein sequence.
4. Frameshift mutations are associated with several genetic disorders, including cystic fibrosis and some types of cancer, highlighting their potential impact on health.
5. In some cases, frameshift mutations may be beneficial, providing genetic diversity that can lead to advantageous traits in certain environments.

Review Questions

• What happens to the protein structure when a frameshift mutation occurs?
  • When a frameshift mutation occurs, it shifts the entire reading frame of the mRNA sequence, leading to changes in all downstream codons. This alteration typically results in the incorporation of incorrect amino acids into the protein, often producing a nonfunctional protein or one with drastically altered function. Additionally, it may introduce premature stop codons, further truncating the protein and impacting its biological activity.
• How do insertion and deletion mutations contribute to frameshift mutations?
  • Insertion and deletion mutations are both types of alterations in DNA sequences that can lead to frameshift mutations. When nucleotides are added (insertion) or removed (deletion) in numbers that are not multiples of three, they shift the reading frame of the genetic code. This results in a completely different sequence of amino acids during translation, leading to potentially severe effects on protein structure and function.
• Evaluate the implications of frameshift mutations in terms of human health and disease.
  • Frameshift mutations can have significant implications for human health as they may result in proteins that are dysfunctional or completely absent. This can contribute to various genetic disorders such as cystic fibrosis, where disrupted protein function affects critical cellular processes. Additionally, certain frameshift mutations are implicated in cancer development due to their role in creating abnormal proteins that promote uncontrolled cell growth. Understanding these mutations is vital for developing targeted therapies and improving treatment outcomes for affected individuals.

Related terms

Point Mutation: A point mutation is a change in a single nucleotide base pair in DNA, which can result in the substitution of one amino acid for another in a protein.

Insertion Mutation: An insertion mutation occurs when one or more nucleotide pairs are added into a DNA sequence, potentially causing a frameshift if not in multiples of three.

Deletion Mutation: A deletion mutation is when one or more nucleotide pairs are removed from a DNA sequence, which can also result in a frameshift if the number deleted is not a multiple of three.