DNA mutations Flashcards
What are some general causes of mutations
-Environmental factors
-Spontaneous mutations
-errors in replication
What is the most common type of mutation
spontaneous mutations
Why do RNA viruses have such a high mutation probability
-Delicacy of RNA backbones
-Lack of proofreading capabilities
Early development mutations have a ______ _______
larger spread
___________ mutations mean every embryo will carry the mutation
Germline
What did Joshua and Esther Lederberg study?
-Proved antibiotic resistance was random
-Bacteria grown with no penicilin exposure developed penicilin resistance
Mismatches make a ____ in the DNA which is recognized by protiens
kink
How does mismatch repair work
-nuclease cleaves a point some distance away from the mismatch
-The nucleotides are removed from the cut strand
-DNA polymerase and DNA ligase close gap
How does base excision repair work
-Uracil signals need for repair
-DNA uracil glycolase cleaves uracil leaving a bare backbone
-The lack of nitrogenous base is detected by AP endonuclease and cleaves the backbone
-DNA polymerase and DNA ligase add a new nucleotide to the bare spot
How does nucleotide excision repair work
-Similar to mismatch
_more than one mismatch is corrected
-Damaged bases signal to enzymes to cleave backbone on either side of the regions
What is another name for single nucleotide pair substitutions
single nucleotide polymorphisms (SNPs)
Which mutations do not change amino acids
Synonymous/Silent
Which mutations change the amino acid
Nonsynonymous/Missense
What kind of mutation causes sickle cell anemia
Missense mutation in the beta globin subunits of hemoglobin, translating valine instead of glutamate
What are nonsense mutations
-Code for premature stop codon
-Shortens polypeptide and can result in a non-functional protein
Which mutation causes cystic fibrosis
Deletion of 3 nucleotides on te CFTR protein, causes improperly formed protein
What is an insertion mutation?
When one or more extra nucleotides are added
What is a deletion mutation?
When a nucleotide is skipped/removed
What is a chromosome deletion?
-A chromosomal fragment is lost leading to gene loss
-If the centromere is lost an entire chromosome can be lost after a few divisions
-May cause death in an embryo
What is a chromosome duplication?
-Small duplications of gene sections
-Can be advantageous amd lead to a new gene being formed
What is a chromosomal inversion?
-Normal sequence is reversed
-Chromosome fragment breaks off and reattaches in reverse order
-Usually does not lead to serious conssequences
What is a chromosomal translocation?
-Portion of a chromosome attaches to a non homolohous chromosome (exchange)
-Can happen when a break occurs
-Can be nondisruptive in noncoding regions
-Gametes may be missing a gene
What is the beta globin gene family?
Consists of 5 different genes expressed at varying times in development, may have arose due from multiple duplication and divergence events evolutionarily
