linda - genetic mutations and DNA repair mechanisms Flashcards
(30 cards)
DNA Damage & Mutation Basics
Why is DNA damage more consequential than RNA or protein damage?
DNA is the permanent copy of the genome; damage affects future cell generations.
DNA Damage & Mutation Basics
What are the two sources of DNA damage?
Spontaneous and induced.
DNA Damage & Mutation Basics
Name the two major forms of spontaneous DNA damage.
Deamination and depurination.
DNA Damage & Mutation Basics
What is deamination?
Removal of an amine group from adenine, cytosine, or guanine.
DNA Damage & Mutation Basics
What is depurination?
Loss of purine bases, resulting in apurinic (AP) sites.
Induced Mutations - Chemical Mutagens
What are base analogs?
Chemicals that mimic normal bases and get incorporated into DNA.
Induced Mutations - Chemical Mutagens
Give an example of a base analog.
5-bromouracil (5-BU) can replace thymine.
Induced Mutations - Chemical Mutagens
What does 2-aminopurine (2-AP) do?
It gets incorporated as adenine instead of thymine.
Induced Mutations - Chemical Mutagens
What do base modifiers do?
Chemically alter DNA bases (e.g., nitrous oxide deaminates adenine).
Induced Mutations - Chemical Mutagens
How do intercalators like ethidium bromide affect DNA?
They insert between base pairs, causing insertions or deletions.
Induced Mutations - Physical Mutagens
What damage does UV light cause to DNA?
Forms pyrimidine dimers that distort the double helix.
Induced Mutations - Physical Mutagens
What is the effect of ionizing radiation on DNA?
Causes single or double-strand breaks.
Types of Mutations
What are microlesions and macrolesions?
Microlesions affect single nucleotides; macrolesions affect multiple.
Types of Mutations
What are three types of point mutations?
Missense, nonsense, and silent mutations.
Types of Mutations
What is a frameshift mutation?
Insertion or deletion that shifts the reading frame.
Mutation Effects & Reversion
What are two basic mutation effects?
Loss of function and gain of function.
Mutation Effects & Reversion
What is a polar mutation?
A mutation in one gene that affects downstream genes (common in bacteria).
Mutation Effects & Reversion
Can point mutations be reversed?
Yes, they are reversible.
Mutation Effects & Reversion
What is a true revertant?
A mutation that restores the original DNA sequence.
Mutation Effects & Reversion
What is a pseudorevertant?
A second mutation restores phenotype without fixing original mutation.
Suppressor Mutations
What is an intragenic suppressor mutation?
Suppressor occurs in the same gene as the primary mutation.
Suppressor Mutations
What is an intergenic suppressor mutation?
Suppressor occurs in a different gene.
Why Mutations Matter
Why are mutations important for evolution?
They introduce genetic diversity; some aid adaptation.
Why Mutations Matter
What is an auxotroph?
A mutant that cannot synthesize a compound required for growth.
