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41 Cards in this Set

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Selective mutations
Confer an advantage on the cell under certain environmental conditions; ex antibiotic resistance. Here the progeny can outgrow and replace the parent
Unselective Mutations
Athought they can have phenotypic effect, they do not confer an advantage; ie loss of pigmentation.
What type of approach does it take to detect unselectable mutant
screening approach
What is replicate plating and example of?
Sceening approach
Novel negative selection that is widely used to isolate auxotrophic mutants.
Penicillin Selection (or enrichment)
Genetic selection
Used for antiobiotic resistant. Resistant cells appear in zone of inhibition.
Auxotrophs
Cells that do not grow on minimal medium, but grow on complete medium.
Spontaneous Mutations
Are the result of the action of natural radiation and errors in replication.
Point Mutations
Most mutations are these, these can be basepair substitutions, insertions or deletions of a single base pair.
A faulty protein would arise from this mutation.
Missense mutation
An incomplete protein would arise from this mutation.
Nonsense mutation
A normal protein would arise from this type of mutation.
Silent mutation
Frameshift
Deletion or insertion of base pairs that disrupts the reading frame of a gene.
Conditional Mutants
Base pair changes when the phenotype of the mutant is observed only under specific growth conditions.
Temperature sensitive
Mutants exhibit a wild type phenotype at low (permissive) temperature and a mutant phenotype at high (nonpermissive) temperatures.
This type of mutation is reversible.
Point mutation
Same site revertant (true revertant)
the change in the base pair is converted back to its original sequence
Second site revertant
A mutation occurs at a site other than the original mutation that restores the phenotype.
Intragenic
When a suppressor mutation occurs on the same gene.
Mutations in a gene encoding a tRNA is an example of what?
Nonsense suppression
These increase the rate of mutagenesis.
Chemical mutagens and DNA repair mutations.
Occurance of a nonsense mutation is
10e-6 -- 10e-8
Alkylating agents
put methyl on G; faulty pairing with T
Ethidium Bromine
Insert between two base pairs
What is the wavelength for UV light
260nm
UV light
Pyrimidine dimer formation
Ionizing radiation (X rays)
Free radical attack on DNA, breaking chain
What is the result of UV or ionizing radiation?
repair may lead to error or deletion
Ethidium bromide results in?
Microinsertions and microdeletions
Alkyating agents result in?
GC-->AT
Bromouracil
Incorporated like T; occasionally faulty pairing with G
What is the result of adding BU?
AT pair-->GC pair occasionally GC--> AT
What is an assay fir reversion of an auxotrophic his mutant?
Ames Test
Transposable elements
mobile DNA elements that can "jump" into new sites of the genome.
Conservative insertion
The original element moves from one position to another with no increase in the numnber elements.
Replicative Insertion
Where the reaction leads to the insertion of a copy of the original element into a second location leading to an increase in number of elements.
What happens when an element inserts onto a gene?
causes loss of function.
Transposase
An enzyme that catalyzes the transfer of the element from one positon to another and they are specific for their resepective repeats.
Inverted repeats
Are specifically recognized by the transposase usually <50 bp.
Direct repeats
Short repeats of the chromosomal target (insertion site) ususally <10 bp.
What type of bacteria are able to undergo Natural competence?
Gram +