Frameshift mutation

Definition

A frameshift mutation is a genetic alteration caused by the insertion or deletion of nucleotides in a DNA sequence that shifts the reading frame of the genetic code. This type of mutation disrupts the normal grouping of codons during translation, often resulting in completely different and nonfunctional proteins. It can lead to significant changes in an organism's phenotype and may contribute to various diseases or disorders.

5 Must Know Facts For Your Next Test

1. Frameshift mutations can occur due to environmental factors such as radiation or chemicals that damage DNA.
2. These mutations often lead to premature stop codons, resulting in truncated proteins that cannot perform their normal functions.
3. Frameshift mutations can affect any gene, but certain genes may be more prone to these alterations based on their sequence structure.
4. If a frameshift mutation occurs in a germline cell, it can be inherited by offspring and affect the entire organism.
5. In some cases, frameshift mutations can provide beneficial adaptations; however, they are more commonly associated with genetic diseases and disorders.

Review Questions

• How does a frameshift mutation impact protein synthesis compared to other types of mutations?
  • A frameshift mutation significantly alters protein synthesis by shifting the reading frame of the genetic code. This contrasts with point mutations, which may only change one codon without affecting the overall reading frame. As a result, frameshift mutations can lead to entirely different amino acid sequences downstream of the mutation site, often producing nonfunctional or dysfunctional proteins, while point mutations may have milder effects depending on their location.
• Discuss the mechanisms by which frameshift mutations can occur and their implications for DNA repair mechanisms.
  • Frameshift mutations can occur through various mechanisms such as insertion or deletion of nucleotides during DNA replication or as a result of DNA damage from external factors. When these mutations arise, DNA repair mechanisms like mismatch repair may not correctly identify the altered sequence due to the shift in reading frame. This can lead to persistent errors in the genetic code if the repair process fails, increasing the risk of diseases like cancer due to malfunctioning proteins.
• Evaluate the potential consequences of frameshift mutations on an organism's fitness and evolutionary adaptation.
  • Frameshift mutations can have profound effects on an organism's fitness by creating nonfunctional proteins that disrupt essential biological processes. While many frameshift mutations are deleterious and associated with genetic disorders, some may provide advantageous traits that enhance survival in specific environments. Over time, these beneficial mutations can contribute to evolutionary adaptation, allowing species to thrive under changing conditions. The balance between harmful and beneficial outcomes shapes genetic diversity within populations.

Related terms

nucleotide:

The basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

codon: A sequence of three nucleotides that corresponds to a specific amino acid or stop signal during protein synthesis.

point mutation:

A genetic mutation where a single nucleotide is substituted, deleted, or inserted, potentially altering a single codon without changing the overall reading frame.