DNA Damage and Repair Mechanisms

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson
Download our mobile app to listen on the go
Get App

Questions and Answers

What is the most common result of deamination in DNA?

  • Conversion of adenine to thymine
  • Conversion of thymine to uracil
  • Conversion of cytosine to uracil (correct)
  • Conversion of guanine to cytosine

What is the primary effect of UV radiation on DNA?

  • Increases oxidation of bases
  • Alters base pairing properties
  • Forms pyrimidine dimers (correct)
  • Induces double strand breaks

What consequence does alkylation of guanine have on DNA?

  • It correctly pairs with cytosine
  • It permits guanine to pair with thymine (correct)
  • It prevents DNA replication
  • It allows guanine to bind with adenine

What is a potential outcome of incorporating base analogues during DNA replication?

<p>Formation of tautomeric forms (D)</p> Signup and view all the answers

What type of agents are intercalating agents in relation to DNA structure?

<p>They cause small insertions or deletions (A)</p> Signup and view all the answers

Flashcards

Deamination

The spontaneous removal of an amine group from a base in DNA, often converting cytosine to uracil. This can lead to errors in DNA replication.

Depurination

The loss of a purine base (adenine or guanine) from the DNA backbone, leaving an abasic site. This can disrupt DNA replication and lead to frameshift mutations.

Thymine Dimers

A type of DNA damage caused by UV radiation, where adjacent pyrimidines (like thymine) form covalent bonds, creating distortions in the DNA backbone. This can block DNA replication and transcription.

Alkylation

The transfer of methyl or ethyl groups to DNA bases or the phosphate backbone. This can lead to base pair changes during replication if not repaired.

Signup and view all the flashcards

Oxidative Damage to DNA

DNA damage caused by reactive oxygen species, where guanine can be oxidized and mispair with adenine during replication.

Signup and view all the flashcards

Study Notes

Spontaneous Hydrolysis of DNA

  • Amine loss can cause DNA mismatches. Cytosine deamination is a common example, changing cytosine to uracil.
  • Depurination involves the loss of a purine base (guanine or adenine) from the DNA backbone. This creates an abasic site, leading to frameshift mutations.

DNA Damage by Radiation

  • UV radiation creates DNA photoproducts, mainly thymine dimers, between adjacent pyrimidines. This covalent linkage distorts the DNA backbone, hindering replication and transcription.
  • Ionizing radiation can cause double-strand breaks in DNA.

Chemical Modification of DNA

  • Alkylation involves the transfer of methyl or ethyl groups to DNA bases or the phosphate backbone. This can result in base-pair changes during replication if not repaired. Example: alkylation of guanine can cause mispairing with thymine.
  • Oxidation can occur when DNA reacts with oxygen species. Oxidative damage to guanine can lead to mispairing with adenine.

Base Analogues and Intercalating Agents

  • Base analogues resemble DNA bases and are incorporated during replication, introducing errors. 5-bromouracil, for example, can replace thymine and mispair with guanine.
  • Intercalating agents, with polycyclic rings, bind between DNA bases causing insertions or deletions in DNA sequence. These agents distort the DNA structure.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser