Deletion mutation

Definition

A deletion mutation is a type of genetic alteration where one or more nucleotides are removed from the DNA sequence. This loss can lead to significant changes in the structure and function of proteins, potentially resulting in diseases or phenotypic variations. The effects of deletion mutations can vary depending on their location within a gene and the number of nucleotides deleted, which may disrupt reading frames and lead to the production of nonfunctional proteins.

5 Must Know Facts For Your Next Test

1. Deletion mutations can occur spontaneously during DNA replication or be induced by environmental factors such as radiation or chemicals.
2. The impact of a deletion mutation on an organism can be severe, particularly if it occurs in a coding region that alters essential proteins for cell function.
3. Some deletion mutations are small, affecting only one or two nucleotides, while others may involve large segments of DNA and several genes.
4. In some cases, deletion mutations can lead to beneficial traits that may provide an adaptive advantage to organisms in their environments.
5. Genetic disorders such as cystic fibrosis and certain types of muscular dystrophy can arise due to specific deletion mutations within critical genes.

Review Questions

• How does a deletion mutation differ from other types of mutations like insertion or substitution?
  • A deletion mutation specifically involves the removal of one or more nucleotides from the DNA sequence, while insertion mutations add extra nucleotides. Substitution mutations replace one nucleotide with another. The key difference lies in how these changes affect the genetic code; deletion and insertion can cause frameshift mutations that alter the reading frame, leading to completely different protein sequences. In contrast, substitution may only change a single amino acid if it does not affect the overall reading frame.
• Discuss how deletion mutations can impact protein synthesis and organismal phenotype.
  • Deletion mutations can significantly disrupt protein synthesis by altering the amino acid sequence produced during translation. When nucleotides are deleted, especially within coding regions, it often results in frameshifts that change how ribosomes read the mRNA. This can lead to premature stop codons and nonfunctional proteins, ultimately affecting an organism's phenotype by potentially causing diseases or morphological changes. For example, certain forms of muscular dystrophy arise from specific deletion mutations that impact muscle protein function.
• Evaluate the role of deletion mutations in evolution and adaptation within populations.
  • Deletion mutations play a complex role in evolution by introducing genetic variation into populations. While many deletions can be harmful or neutral, some may confer advantages under specific environmental conditions. For instance, a deletion that results in a shorter but more efficient enzyme could enhance metabolic processes beneficial for survival. Over time, natural selection may favor individuals with advantageous deletions, promoting their propagation within the gene pool. This interplay between mutation and selection highlights how genetic changes contribute to evolutionary dynamics and adaptations across diverse environments.

Related terms

frameshift mutation: A genetic mutation caused by the insertion or deletion of nucleotides that shifts the reading frame of the genetic code, often leading to altered or nonfunctional proteins.

point mutation: A type of mutation involving a change in a single nucleotide base pair, which can result in silent, missense, or nonsense mutations.

chromosomal deletion: A larger-scale genetic alteration involving the loss of a segment of a chromosome, which can affect multiple genes and lead to various genetic disorders.