DNA Damage

Definition

DNA damage refers to alterations or lesions that occur in the DNA molecule, disrupting its normal structure and function. This type of damage can be caused by various environmental factors and cellular processes, and if left unrepaired, can lead to genetic mutations and potentially contribute to the development of diseases like cancer.

5 Must Know Facts For Your Next Test

1. Radiation, including both ionizing and non-ionizing radiation, can directly damage DNA by breaking chemical bonds and causing single-strand or double-strand breaks.
2. Reactive oxygen species (ROS) generated during normal cellular metabolism can also lead to oxidative DNA damage, such as the formation of 8-oxoguanine.
3. DNA damage can disrupt the normal replication and transcription processes, potentially leading to the incorporation of incorrect nucleotides and the formation of mutations.
4. Cells have evolved various DNA repair mechanisms, such as base excision repair, nucleotide excision repair, and mismatch repair, to maintain the integrity of the genome.
5. Unrepaired or misrepaired DNA damage can trigger cellular responses, including cell cycle arrest, senescence, or apoptosis, to prevent the propagation of cells with potentially harmful mutations.

Review Questions

• Explain the different types of DNA damage that can occur and how they are caused.
  • DNA damage can occur through various mechanisms, including direct breaks in the DNA strands caused by ionizing radiation, as well as the formation of bulky adducts or oxidative lesions due to exposure to ultraviolet radiation or reactive oxygen species. These different types of DNA damage can disrupt the normal structure and function of the DNA molecule, potentially leading to the incorporation of incorrect nucleotides during replication or transcription, and ultimately resulting in genetic mutations.
• Describe the cellular mechanisms involved in the repair of DNA damage.
  • Cells have evolved several DNA repair mechanisms to maintain the integrity of the genome, including base excision repair, nucleotide excision repair, and mismatch repair. These repair pathways involve the recognition of the DNA damage, the removal of the damaged or incorrect DNA segments, and the subsequent replacement with the correct nucleotides. The efficient functioning of these repair mechanisms is crucial for preventing the propagation of cells with potentially harmful mutations that could contribute to the development of diseases like cancer.
• Analyze the potential consequences of unrepaired or misrepaired DNA damage and how cellular responses can mitigate these effects.
  • Unrepaired or misrepaired DNA damage can have serious consequences for the cell, as it can disrupt normal cellular processes like replication and transcription, leading to the incorporation of incorrect nucleotides and the formation of genetic mutations. To prevent the propagation of cells with potentially harmful mutations, cells have evolved various cellular responses, such as cell cycle arrest, senescence, and apoptosis. These responses can temporarily halt the cell's division or trigger programmed cell death, effectively removing the damaged cell from the population and preventing the spread of mutations that could contribute to the development of diseases like cancer.

Related terms

Oxidative Stress: An imbalance between the production of free radicals and the body's ability to detoxify them, leading to potential damage to cellular components, including DNA.

Nucleotide Excision Repair: A DNA repair mechanism that removes and replaces DNA segments containing damaged nucleotides, such as those caused by ultraviolet radiation.

Apoptosis: A programmed cell death process that can be triggered by severe DNA damage, preventing the propagation of cells with potentially harmful mutations.