Deletion

Definition

Deletion is a type of mutation where a segment of DNA is removed or lost from a chromosome. This can lead to various effects depending on the size and location of the deleted segment, potentially resulting in genetic disorders or altered gene function. Understanding deletions is crucial in studying inheritance patterns, especially concerning organelle genes and their roles in cellular functions.

5 Must Know Facts For Your Next Test

1. Deletions can occur in various sizes, ranging from a single nucleotide to large segments of a chromosome, affecting multiple genes.
2. The effects of a deletion often depend on whether it occurs in a coding region or regulatory region of a gene; coding region deletions typically lead to loss of function.
3. In organelles like mitochondria, deletions can affect energy production and may contribute to mitochondrial diseases.
4. Some deletions can result in frameshift mutations, altering the reading frame of the genetic code and leading to entirely different protein products.
5. Deletions are often associated with genetic disorders such as Cri du Chat syndrome, which is caused by a deletion on chromosome 5.

Review Questions

• How do deletions influence gene function and phenotypic expression?
  • Deletions can have significant impacts on gene function by removing crucial DNA sequences necessary for protein coding or regulation. When a segment of DNA is deleted, it may lead to loss-of-function mutations, where proteins are either not produced or produced incorrectly. This change in gene expression can manifest as altered phenotypes, such as developmental abnormalities or increased susceptibility to diseases.
• Discuss the implications of deletions within organelle genes and how they might affect cellular functions.
  • Deletions within organelle genes, particularly in mitochondria, can severely disrupt cellular functions such as ATP production. Mitochondrial deletions may lead to reduced energy availability for the cell, causing symptoms like muscle weakness or neurological issues. Additionally, since mitochondria are involved in apoptosis and reactive oxygen species management, deletions can also trigger broader metabolic dysfunctions that affect overall organism health.
• Evaluate the potential role of deletion mutations in the development of genetic disorders and their inheritance patterns.
  • Deletion mutations can play a critical role in the development of various genetic disorders by disrupting essential genes required for normal biological functions. The inheritance patterns of these disorders often depend on whether the deletion occurs in dominant or recessive alleles. For instance, certain deletions can be inherited as autosomal dominant traits if they lead to a gain-of-function effect, while others may exhibit autosomal recessive inheritance if both alleles must carry the deletion for the disorder to manifest. Understanding these patterns aids in predicting outcomes for offspring when one or both parents carry deletion mutations.

Related terms

Mutation: A permanent alteration in the DNA sequence that makes up a gene, which can lead to changes in phenotype.

Gene Expression: The process by which information from a gene is used to synthesize functional gene products, typically proteins.

Chromosomal Abnormalities: Any change in the normal structure or number of chromosomes, which can be caused by deletions, duplications, or other mutations.