Frameshift mutation

Definition

A frameshift mutation is a genetic alteration that occurs when nucleotides are inserted or deleted from the DNA sequence, causing a shift in the reading frame of the genetic code. This type of mutation can lead to significant changes in the resulting protein, often resulting in loss of function or the production of an entirely different protein. Since the genetic code is read in triplets, the insertion or deletion of a single nucleotide alters all subsequent codons, which has serious implications for protein synthesis and can contribute to genetic disorders and inherited diseases.

5 Must Know Facts For Your Next Test

1. Frameshift mutations can arise from errors during DNA replication or from exposure to certain mutagens, such as chemicals or radiation.
2. The impact of a frameshift mutation is often more severe than that of a point mutation because it changes the entire downstream sequence, leading to potentially nonfunctional proteins.
3. Many genetic disorders, such as cystic fibrosis and some forms of muscular dystrophy, can be attributed to frameshift mutations that disrupt essential genes.
4. Frameshift mutations can either be caused by insertions or deletions of nucleotides, with even a single nucleotide change having dramatic effects on the protein produced.
5. In some cases, frameshift mutations may lead to gain-of-function effects if they result in a new protein with novel functions, although this is less common.

Review Questions

• How do frameshift mutations differ from point mutations in terms of their effects on protein synthesis?
  • Frameshift mutations differ from point mutations primarily in their impact on the reading frame of the genetic code. While point mutations change only one nucleotide and may affect only one codon, frameshift mutations alter the entire downstream sequence by inserting or deleting nucleotides. This shift can drastically change all amino acids that follow the mutation site, often resulting in completely nonfunctional proteins or proteins with altered functions.
• Discuss how frameshift mutations can contribute to genetic disorders and inherited diseases.
  • Frameshift mutations can contribute to genetic disorders and inherited diseases by disrupting essential genes necessary for normal cellular functions. When these mutations occur within crucial genes, they can produce nonfunctional proteins or truncated proteins that fail to perform their roles. For example, frameshift mutations in genes like CFTR are responsible for cystic fibrosis, illustrating how such genetic alterations can lead to severe health issues that are passed down through generations.
• Evaluate the role of frameshift mutations in evolutionary processes and their potential impact on population genetics.
  • Frameshift mutations play a significant role in evolutionary processes by introducing genetic variability within populations. These mutations can create new traits that may be beneficial, neutral, or harmful, influencing an organism's fitness and survival. In population genetics, frameshift mutations contribute to genetic diversity, which is crucial for natural selection and adaptation. While many frameshift mutations are deleterious and may lead to disease, rare instances where they confer advantageous traits can drive evolution and shape species over time.

Related terms

point mutation: A point mutation is a change in a single nucleotide base pair in the DNA sequence, which can lead to a different amino acid being incorporated into a protein.

nonsense mutation: A nonsense mutation is a specific type of point mutation that results in a premature stop codon, leading to truncated proteins that are often nonfunctional.

gene expression:

Gene expression is the process by which the information encoded in a gene is used to synthesize functional gene products, usually proteins, which are essential for cellular functions.