Mutations are inherited alterations in the DNA sequence

expanding nt repeats

mutations in which number of copies of a set of nt increases

Forward mutations

mutations that alter the wild-type phenotype

Huntington disease

nucleotide expands within the coding part of a gene producess toxic protein w extra glutamin residues increase in number of nt repeats

intergenic suppressor protein

\suppresses the effect of an earlier mutation made in another gene

somatic mutations

arise in somatic tissues which do not produce gametes divides in MITOSIS genetically identical cells earlier mutation, larger the clone

missense mutation

base substitution results in a different amino acid in the protein

gain of function mutation

causes cell to produce a protein or gene product whose function is not normally present

Germ line mutations

cells that ultimately produce gametes can be passed to future generations future generations get passed mutation in somatic and germ-line cells

silent mutation

changes a codon to a ynonymous codon that specifies an amino acid

nonsense mutation

changes a sense codon into a NONSENSE codon terminates translation if occurs early, result is nonfunctional protein

frame-shift mutations

changes in the reading frame of the gene cause by insertions and deletions

reverse mutations

changes mutant phenotype back to wildtype

loss of function mutation

complete or partial absence of normal protein function frequently recessive

FMR-1

expanding nt repeat mutation fragile-X syndrome: fragile sites tip of each long arm of X attached by slender part of chromosome CGG= repeeated site

conditional mutation

expressed only under certain conditions

mutation rates

frequency with which a wild-type allele at a locus changes into a mutant allele

indels

gene mutations containing insertions and deletions addition/removal of one or more nucleotide pairs

gene versus chromosome mutations

gene: single genes, only detected via observation of phenotypic effect Chromosome: affects structure , observed directly via microscope

suppressor mutation

genetic change that hides or suppresses the effect of another mutation occurs at a site distinct from site of original mutation DOUBLE MUTANT

in-frame insertions/deletions

indels not affecting reading frame when nt pair is added or removed

mutation

inherited change in genetic information: descendants may be cells or organisms

neutral mutation

missense mutation alters the amino acid sequence of a protein but does not significantly change function

lethal mutations

premature death

phenotypic effects can happen with silent mutations Y/N?

Hell yeah they can

Base substitutions

simplest gene mutation alteration of a single nt in the DNA

Gene mutation

small DNA lesion that affects a single gene

2 broad mutation categories of multicellular organisms

somatic and germline mutations

adaptive mutations

stressful environments can induce more mutations in bacteria

Intragenic suppressor mutation

suppresses the effect of an earlier mutation within the same gene

two types of base substitutions

transition: purine replaced by a different purine, or pyrimidine replaced by pyrimidine transversion: purine replaced by pyrimidine or pyrimidine replaced by a purine transversions twice the number of transitions BUT transitions arise more frequently

result of frame-shift mutations

usuaally alter all amino acids encoded by nucleotides following the mutation drastic effect on phenotype introduce premature stop codons