Deletion

Definition

Deletion refers to a type of genetic mutation where a part of the DNA sequence is lost or removed. This loss can occur in a variety of ways, such as through errors during DNA replication or from external factors like radiation. Deletions can significantly affect the structure and function of genes, potentially leading to various genetic disorders or diseases.

5 Must Know Facts For Your Next Test

1. Deletions can range from small segments of a few nucleotides to large sections that encompass entire genes or even entire chromosomes.
2. Some deletions are benign and do not affect an organism's health, while others can lead to severe genetic disorders such as cystic fibrosis or Duchenne muscular dystrophy.
3. When a deletion occurs within a gene, it can disrupt the normal coding sequence, potentially leading to nonfunctional proteins or proteins with altered functions.
4. In some cases, deletions can lead to frame shifts, resulting in drastically changed amino acid sequences and possibly creating stop codons that truncate protein synthesis.
5. Deletions are often studied in genetic research to understand their implications in evolution, disease, and the development of various traits in organisms.

Review Questions

• How does a deletion mutation affect gene expression and protein synthesis?
  • A deletion mutation can have a profound impact on gene expression and protein synthesis by removing essential segments of DNA that code for specific amino acids. This loss may lead to nonfunctional proteins or proteins with altered functions if the deletion occurs within a coding region. Additionally, if the deletion results in a frame shift, it changes the reading frame of the mRNA during translation, potentially producing entirely different proteins or introducing premature stop codons that terminate translation early.
• Discuss the potential consequences of large chromosomal deletions on an organism's phenotype and overall health.
  • Large chromosomal deletions can result in the loss of multiple genes and regulatory regions, leading to significant changes in an organism's phenotype and overall health. These deletions can disrupt essential biological processes and lead to developmental issues, congenital abnormalities, or genetic disorders. For example, Williams syndrome is caused by a deletion of about 26 genes on chromosome 7, leading to characteristic facial features and cardiovascular problems. The broader implications depend on which genes are deleted and their roles in cellular functions.
• Evaluate the role of deletion mutations in evolutionary processes and their contribution to genetic diversity.
  • Deletion mutations play a critical role in evolutionary processes by contributing to genetic diversity within populations. While many deletions can be harmful or neutral, some can provide advantageous traits that enhance an organism's survival and reproduction in changing environments. For example, a deletion that removes a nonessential gene may allow for more efficient energy use or adaptability to stressors. Over time, these beneficial deletions can become fixed in populations through natural selection, shaping the genetic landscape of species and influencing evolutionary trajectories.

Related terms

mutation:

A change in the DNA sequence that can lead to alterations in gene function and may result in various phenotypic effects.

chromosomal aberration: A structural alteration of chromosomes, which can involve deletions, duplications, inversions, or translocations of chromosome segments.

frame shift: A type of mutation caused by deletions or insertions that changes the reading frame of the genetic code, potentially resulting in a completely different translation from the original.