Mutation Flashcards
Chapter 4
What is a mutation?
A heritable change in an organism’s DNA sequence that may lead to altered phenotype.
What is a mutant?
An organism with a mutation, potentially showing a change in phenotype.
What is the wild type?
The phenotype most commonly observed in nature.
What is a point mutation?
A mutation that affects a single base in the DNA sequence.
What are the classes of point mutations?
Substitution, insertion, and deletion.
What is a substitution mutation?
A mutation where one base is replaced by another.
What is an insertion mutation?
The addition of one or more bases into the DNA sequence.
What is a deletion mutation?
The removal of one or more bases from the DNA sequence.
What is a silent mutation?
A mutation that does not alter the amino acid sequence of the protein.
What is a missense mutation?
A mutation that results in a different amino acid being incorporated into the protein.
What is a conditional mutation?
: A missense mutation whose effects are apparent only under certain conditions.
What is a nonsense mutation?
A mutation that converts an amino acid codon into a stop codon, producing a truncated protein.
What causes a frameshift mutation?
Insertions or deletions not in multiples of three, altering the reading frame of mRNA.
Why are frameshift mutations problematic?
hey change every amino acid after the mutation and often result in nonfunctional proteins.
What are spontaneous mutations?
Mutations caused by errors during DNA replication.
What are induced mutations?
Mutations caused by exposure to mutagens like chemicals or radiation.
What are nucleoside analogs?
Molecules structurally similar to nucleotide bases that cause mismatched base pairing.
What is an example of a nucleotide-modifying agent?
Nitrous acid, which deaminates cytosine to uracil, converting GC pairs to AT pairs.
What are intercalating agents?
Chemicals that insert between DNA bases, causing insertions or deletions.
What is ionizing radiation?
igh-energy radiation (e.g., X-rays) that causes DNA breaks and base modifications.
What is non-ionizing radiation?
UV light, which induces thymine dimers and stalls DNA replication.
What is proofreading in DNA replication?
DNA polymerase corrects mismatched bases during replication.
What is mismatch repair?
A mechanism that corrects replication errors after the replication machinery has passed.
What is nucleotide excision repair?
A repair mechanism that removes thymine dimers and replaces them with correct nucleotides.
