Chapter 11 Flashcards
Mutations that occur in germ-line cells, giving rise to sperm and egg, are called __________
germ-line mutations
Cells not in the germ line are called somatic cells; mutations in such cells are called _______
somatic mutations
Germ-line mutations _______ be passed from one generation to the next, while only _______ descendants of the original mutated somatic cell will carry the mutation
can
direct
localized mutations or _______ occur at a specific identifiable position in a gene
point mutation
Genes with elevated mutation rates are called _______
mutation hot spots
What are the 2 different types of base-pair substitution mutations?
1) transitions
2) transversions
What substitution results in transitions?
A to G (vice versa)
C to T (vice versa)
What are the 3 results that can result from a base pair substitution?
1) silent mutation
2) missense mutation
3) nonsense mutation
_______: no amino acid change
silent mutation
_______: changes in amino acid
missense mutation
_______: creates a premature stop codon
nonsense mutation
_______ or _______ of one or more base pairs altering the reading frame of the message
insertion or deletion
insertion or deletion of one or more base pairs that alters the reading frame results in _______
frameshift mutations
Mutations that alter consensus sequence nucleotides of promoters are called _______
promotor mutations
promotor mutations interfere with the efficiency of _______
transcription initiation
Mutations that alter mRNA required for specific sequences at either end of the intron are called _______
splicing mutations
Base-pair substitutions that results in the production of new splice sites that replace or compete with authentic splice sites during mRNA processing are called _______
cryptic splice sites
polyadenylation mutations can _______ proper 3’ processing of mRNA
block
_______: converts a wild type allele to a mutant allele
forward mutation
_______: convert mutant alleles to wild-type or near wild-type
reverse mutations or reversions
_______: wild-type DNA sequence is restored by a second mutation within the SAME codon
true reversion
_______ is reversion that occurs through mutation elsewhere in the same gene
intragenic reversion
_______ occurs by a mutation in a different gene and together the two mutations restore the organism to wild-type
second-site reversion
Second site reversions are also known as _______ because the second mutation “suppresses” the mutant phenotype caused by the first mutation
suppressor mutations
_______ can arise in cells without exposure to agents capable of inducing mutations
spontaneous mutations
Spontaneous mutations arise primarily through errors in _______ or spontaneous changes in the chemical structure of a _______
DNA replication
nucleotide base
Alterations in the number of DNA repeats occur via _______; which results in a portion of the DNA forming a temporary hairpin
strand slippage
_______ are a special class of mutations causing some hereditary diseases in humans and other organisms where increases in number of repeats beyond a certain threshold causes disorders
Trinucleotide repeat disorders
_______: the loss of a purine from a nucleotide by breaking the covalent bond linking the nucleotide base to the sugar
Depurination
The site where the loss of a purine occurs is called the _______ site
apurinic
If left unrepaired, DNA polymerase will usually compensate by putting a(n) _______ into the site during replication
adenine
_______: the loss of an amine group (NH2) form a nucleotide
deamination
When a cytosine is deamninated, an oxygen atom usually takes its place, converting the cytosine into a _______
uracil
When methylated cytosine is deaminated, a _______ base is produced
thymine
Agents that cause DNA damage leading to mutation are called _______
mutagens
_______ can fit between DNA base pairs and distort the DNA duplex
intercalating agents
Intercalating agents lead to distortion that can lead to _______ resulting in added or lost nucleotides
DNA nicking
_______ are aberrant structures with additional bonds involving nucleotides; caused by UV irradiation
photoproducts
What are the 2 photoproducts?
1) Thymine dimer
2) 6-4 photoproduct
- both occur between thymines
Radiation such as X-rays, Gamma rays, and radioactive materials can cause _______ or _______ breaks in DNA that block DNA replication
single-strand
double-strand
