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26 Cards in this Set
- Front
- Back
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define a mutation
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heritable change to the genetic information
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does a mutaion have to be passed to the next generation
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no. could be in a somatic cell
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compare error and mutation
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an error can be corrected
a mtation is a set mistake that cannot return to the original sequence |
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when does an error become a mutation
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after replication occurs
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in a mutant from the germline. will all or just some cells hold the mtuation
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all the new cells will carry the mutation
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what are two types of mutation
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subsitution
insertion/deletion |
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what is the difference between transition and transversion
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transition is a purine for a purine ie. G->A or A-->G
transversion is pyr for a purine so C->A C->G T->A t->C |
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what are the possible phenotypic effects of mutations on proteins
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missense
nonsense silent |
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why is it that we can have so many mutations but very few really affect us
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not all change the phenotype
silent mutations two copies of most genes and usually one is enough some mutations are conditional aa change may not alter the function if it is similar |
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where might a mutation occur that does not affect protein coding regions but does affect the phenotype
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promoter
mutation to splicing |
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what are the two categories of mutations
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spontaneous
induced |
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define spontaneous mutation
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occur due to normal cellular chmeistry ex. oxidative radicals or depurination
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what is the major form of spontaneous mutation we talked about
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tautomeric shifts between the keto and enol forms of the gases
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what are two examples of spontaenous chemcial changes
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depurination
deamination |
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define depurination
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loss of a purine base during DNA rep. random nt is incorporated in vitro cell culture
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define deamination
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loss of an amino group. this alters base pairing properties
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in deamination cytosine changes to ____
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uracil
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in deamination adenine changes to _____
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hypoxanthine
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give fourexamples of induced mutations
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base analogs
alkylating agents intercalating agents radiation |
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how do euk cells respond to UV light
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euk have pol eta which adds 2As across from teh dimer
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name three DNA repair pathways
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Base excision repair
nucleotide excision repair mismatch repair |
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t or f. mismatch, BER, and NER, occur in both euk and prok
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TRUE
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describe mismatch repair
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occurs directly after DNA replication during a limited tiem frame
Ecoli is methylated at A in GATC. After dNA replication old strand is methylated, new is not and mut H binds then S then L and a nick ensues. The H chews and removes DNA back past the mismatch. DNA pol refills and ligase seals |
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describe base excision repair
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damaged base in the DNA
this is recognized by DNA glycosylase removes damaged pr base creates AP site AP endonuclease recognizes AP and removes sugar and phosphate DNA pol fills ligase |
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describe NER
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removes bulky lesions like pyr dimers
coudl be used to repair mismatch UVR A B C D identify damage and remove damaged nucleotides |
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what is XP
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xeroderma pigmentosa is a disorder in which NER can't repair UV damage
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