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18 Cards in this Set

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Mutation
change in nucleotide base sequence of a gene
(change in genotype)
(change in phenotype=mutant)
Mutation properties
=ultimate source of genetic variation; resulted in all organisms on earth
Most are bad for individuals (lowers fitness)
Germline mutations
affect gametes
(subsequent generations)
Somatic mutations
affect body cells
(not passed on)
Sickel Cell Anemia
1 bp substitution
(Val substituted for Glu)
Causes hemoglobin to be "sticky" (sickeling of blood cells)
Causes of Mutations
Spontaneous: generated spontaneously
Induced: chemicals or radiation
Spontaneous Mutations
Result in genetic conditions that are not inherited
DNA nitrogenous bases (ATCG) are chemically unstable and mismatched base pairs can result. ex. G pairs w/ A
Rate=1/100,000 chance of mutation per gene
Short-lived organisms have same mutation rate but evolve more rapidly due to short generation time
Mutation hot spots
sites of increased chance of mutation
Usually found in regions where base pairs repeat (ATATAT)
Induced Mutations
ex. Cigs
Chemicals/radiation
ex. sunlight causes thymine dimers- can lead to skin cancer
Point mutation
= change in single DNA base (1 base for another)
Silent mutation
no effect
Missense mutation
replaces one amino acid with another
THQ ONE BIG FLY HAD ONE RED EYE
Nonsense mutation
changes codon for amino acid into "stop" codon
THE ONE BIG___________
Deletion/Insertions
removal/addition of DNA bases
THE ONE BIG HAD ONE RED EYE
THE ONE BIG WET FLY HAD ONE RED EYE
Frameshift mutation
adding or removing bases throws off reading frame of protein synthesis. more damaging
THE ONE QBI GFL YHA DON ERE DEY
Excision repair
Enzymes cut out segment of DNA with mistake
Mismatch repair
remove mismatched bases; replace with correct base
Polymerase eta
=fixes and copies DNA damaged by sunlight (removes thymine dimers)
People with xeroderma pigmentosum lack it and develop skin cancer easily.
=maybe responsible for all terrestrial life