exam 3 (mutations) Flashcards
what is a mutation
permanent alteration to a DNA sequence from its normal
what is an example of a reversible alteration to DNA
cytosine methylation
what is a point mutation
single base change
what is a transition
pyrimidine-purine base pair is replaced with a pyrimidine-purine
what is a transversion
pyrimidine-purine base pair is replaced with a purine-pyrimidine
what are the 4 examples of transitions
A–> G
G –> A
C –> T
T –> C
what are the transversions examples of the 4 bases
A –> T, C
C –> A, G
G –> C, T
T –> A, G
what is a deletion
removal of 1+ base(s)
what is an insertion
addition of 1+ base(s)
what 3 types of mutations are caused from point mutations
synonymous
missense
nonsense
what are synonymous substitutions
mutations that don’t change the amino acid sequence, function of protein is maintained, aka a silent mutation
what is a missense mutation
mutations that change the amino acid sequence of a protein, can be conservative or non-conservative
what is a conservative mutation
amino acid encoded has similar properties of the allele, maintaining protein function and regulation
what is non-conservative mutation
amino acid encoded has different properties than the specified allele, altering function and regulation
what is a nonsense mutation
mutation that inserts a premature stop codon into mRNA sequence, being non-functional protein to be rapidly degraded
what is a frameshift mutation
insertions and deletions of bases (not in multiples of 3), altering the reading and resulting in a different translation
trinucleotide repeat expansion
repeats of a codon for a given amino acid, often causing pathogenic diseases
what mutation results in Huntington’s disease
expansion of CAG repeats, leading to formation of toxic protein aggregates (needs 40+ to for sure infect)
what is the difference between mutations vs polymorphisms
mutation- change away from wild-type allele
polymorphism- allele that is at least somewhat common in a population
how are mutations classified
according to their affect on the function of the gene
what is amorph/null
mutation that causes complete loss of gene function, usually recessive to the wild-type copy of the gene
what is hypomorph
mutation that causes partial loss of gene function
what is hypermorph
mutation that causes an increase in normal function of the encoded protein
what is antimorph
mutation that causes the gene product to act in opposition of its normality, aka dominant negative mutations
what is neomorph
mutation that causes the gene product to obtain a new function
what are structural variations
mutations involved in large-scale alterations in chromosome structure, that affect many genes
what are chromsomal translocations
reciprocal fusion of pieces of chromosomes to on another, often results in cancer
what is the philadelphia chromosome
reciprocal translocation between chromosomes 9 and 22 in chronic leukemia, resulting in uncontrolled cell division
