Single-strand break

Definition

A single-strand break is a type of DNA damage where one of the two strands of the DNA helix is severed, leaving the other strand intact. This form of damage can disrupt normal cellular functions and may result from exposure to radiation or certain chemicals, impacting the integrity of nucleic acids, leading to various types of DNA damage and potentially resulting in mutations during cell replication.

5 Must Know Facts For Your Next Test

1. Single-strand breaks can be repaired by cellular mechanisms such as base excision repair, which is crucial for maintaining genomic stability.
2. These breaks are often caused by ionizing radiation, which can lead to oxidative stress and damage to DNA molecules.
3. While single-strand breaks are less catastrophic than double-strand breaks, they can still contribute to genomic instability if not properly repaired.
4. In some cases, if a single-strand break occurs in a critical region of a gene, it can lead to mutations that may affect protein function and contribute to diseases like cancer.
5. Single-strand breaks are common in cells exposed to environmental stresses and can serve as indicators for assessing the extent of DNA damage in various biological studies.

Review Questions

• How does a single-strand break differ from a double-strand break in terms of its impact on DNA and cellular function?
  • A single-strand break involves the severing of one strand of the DNA helix while leaving the other strand intact, making it generally less harmful than a double-strand break, which compromises both strands. While both types of breaks can lead to mutations and affect cellular function, single-strand breaks can often be repaired more efficiently through specific repair mechanisms like base excision repair. However, if left unrepaired or misrepaired, single-strand breaks can still contribute to genomic instability and potential carcinogenesis.
• What role do cellular repair mechanisms play in addressing single-strand breaks, and why is this important for maintaining genomic integrity?
  • Cellular repair mechanisms like base excision repair play a critical role in addressing single-strand breaks by recognizing and fixing the damaged DNA. This process is vital for maintaining genomic integrity because it helps prevent mutations that could disrupt normal cellular processes and lead to diseases such as cancer. Efficient repair ensures that any damage does not accumulate over time, preserving the fidelity of genetic information during cell division.
• Evaluate how single-strand breaks can lead to mutations and what implications these mutations might have for health and disease.
  • Single-strand breaks can lead to mutations when the repair process is faulty or incomplete, resulting in changes in the DNA sequence. These mutations can have significant implications for health and disease; for example, they may disrupt essential genes or regulatory regions, potentially contributing to cancer development or other genetic disorders. By analyzing the pathways involved in repairing these breaks, researchers can better understand the mechanisms that underlie mutagenesis and develop strategies for targeted therapies in diseases associated with DNA damage.

Related terms

Double-strand break: A more severe form of DNA damage where both strands of the DNA helix are broken, often leading to more complex mutations and higher risks of cell death or cancer.

Base excision repair: A cellular mechanism that repairs single-strand breaks by removing damaged bases and replacing them with the correct nucleotides to maintain DNA integrity.

Mutation: A permanent alteration in the DNA sequence that can occur due to various factors, including single-strand breaks, which may lead to changes in protein function or regulation.