Frameshift mutations

Definition

Frameshift mutations are genetic alterations that occur when nucleotides are added to or deleted from the DNA sequence in a number that is not a multiple of three. This results in a shift in the reading frame of the gene, leading to changes in the amino acid sequence of the resulting protein. Such mutations can have severe effects on protein function and contribute to various genetic disorders.

5 Must Know Facts For Your Next Test

1. Frameshift mutations often lead to a completely different protein being produced, which may be nonfunctional or have altered activity.
2. These mutations can occur due to errors during DNA replication or as a result of exposure to mutagens.
3. The impact of a frameshift mutation depends on where it occurs within the gene; early shifts typically have more drastic effects than those that occur later.
4. Frameshift mutations can result in premature stop codons, truncating the protein and potentially leading to severe phenotypic consequences.
5. They are implicated in various genetic diseases, such as cystic fibrosis and certain cancers, highlighting their importance in population genetics.

Review Questions

• How do frameshift mutations differ from point mutations in their effects on protein synthesis?
  • Frameshift mutations involve the addition or deletion of nucleotides that change the reading frame of the genetic code, leading to widespread alterations in the amino acid sequence of a protein. In contrast, point mutations only affect a single nucleotide, which may result in a change of one amino acid or none at all if it’s a silent mutation. This fundamental difference means that frameshift mutations can have far more severe consequences on protein function and stability compared to point mutations.
• Evaluate the role of frameshift mutations as mutagens and their implications for genetic disorders.
  • Frameshift mutations act as significant mutagens because they can disrupt normal protein coding sequences, leading to nonfunctional proteins that contribute to genetic disorders. When frameshift mutations occur in crucial genes involved in cell growth or repair mechanisms, they can initiate pathways that lead to diseases such as cancer. Understanding this relationship helps researchers explore potential therapies and preventative measures against diseases linked to such genetic alterations.
• Synthesize information on how frameshift mutations contribute to evolution and population genetics.
  • Frameshift mutations introduce new genetic variations into a population's gene pool, which can influence evolutionary processes. While many frameshift mutations are deleterious and may be selected against, some can confer beneficial traits that enhance survival and reproductive success under specific environmental conditions. This dynamic between harmful and beneficial frameshift mutations shapes genetic diversity within populations and plays a critical role in natural selection, adaptation, and the overall evolutionary trajectory of species.

Related terms

Point mutations: Point mutations are changes in a single nucleotide base pair in the DNA sequence, which can lead to silent, missense, or nonsense mutations.

Mutagens: Mutagens are environmental factors, such as chemicals or radiation, that can cause changes in the DNA sequence and increase the rate of mutations.

Genetic disorders: Genetic disorders are diseases caused by abnormalities in an individual's DNA, which can arise from various types of mutations, including frameshift mutations.