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46 Cards in this Set
- Front
- Back
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What are the classical approaches to ascribing gene function |
Describe phenotype of mutant Genetic analysis to identify location of gene Analysis of gene Cloning of genes Sequencing of genes |
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What is a mutation |
Heritable change in DNA sequence that can lead to a change in phenotype |
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What is a mutant |
A statin of an cell or virus differing from parental strain in genotype |
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What is a wild type strain |
Typically refers to strain isolate from nature |
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What is a selectable mutation |
Give the mutant brother advantage under certain conditions |
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What are non selectable mutations |
No advantage or disadvantage |
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How do you delete a non selectable mutation |
Examine a large number of colonies and looking for difference (screening) |
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What are induced mutations |
Made environmentally or deliberately can result from exposure to natural radiation or oxygen radicals |
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What are spontaneous mutations |
Occurs without external intervention |
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What are point mutations |
Mutations that only change one base pair can lease to single amino acid change in a protein an incomplete protein |
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What is a silent mutation |
Doesn’t affect amino acid sequence |
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What is a missense mutation |
Amino acid Ed change. Polypeptide altered |
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What is a nonsense mutation |
Codon becomes stop codon polypeptide is incomplete |
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What is a frameshift mutation |
Deletions or insertions that result in a shift in the reading frame. Often result in complete loss of gene function |
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Are point mutations reversible |
Typically yes |
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What is a reversion mutation |
Alteration in DNA that reverses the effects of a prior mutation |
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What do a reverent mutation |
Strain in which original phenotype is restored |
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What’s the two types of revertant mutations |
Same site and second site |
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What is same site revertant |
Mutation is at the same site as original mutation |
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What what is a second site revertant |
Mutation is at a different site in the DNA |
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What is a suppressor mutation |
Mutation that compensated for the effect of the original mutation |
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What is the error rate in DNA replication |
10-6 to 10-7 per kilo base |
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What are the mutation rates in RNA genomes compared to DNA |
1000 fold higher |
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What are the different types of mutagens |
Chemical Physical Biological |
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What are the classes for chemical mutagens |
Nucleotide bass analogs- resemble nucleotides Inducers if chemical modifications Chemical mutagens that cause frameshifts |
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What are the two main categories of mutagenic electromagnetic radiation |
Nonionising Ionising |
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What are examples of nonionising mutagens |
Uv radiation |
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What is an example of ionising mutants |
X rays Gamma rays Cosmic rays |
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What absorb nonionsing mutants |
Purines and pyramidines |
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What are the three types of DNA repair |
Direct reversals Repair of single strand damage Repair of double strand damage |
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What is direct reversal DNA repair |
Mutated base still recognisable and can be repaired without referring other strand |
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What are ss damage repairs in DNA repair |
Damaged DNA is removed and repaired using opposite strand as template |
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What if ds DNA repair |
SOS regulatory system Allows relocation to proceed and cell to replicate but errors more likely Translesion synthesis allows DNA to be synthesised with no template |
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What is translesion |
Synthesis allows DNA to be synthesised with no template |
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What is recombination |
Physical exchange of DNA between genetic elements |
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What is homologous recombination |
Process that results in genetic E change between homologous dna from two different sources Selective medium can be used to defect rare genetic recombinants |
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What are transposable elements |
Discrete segments if DNA that move as a unit from one location to another within tiger DNA molecules |
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Where can transposable elements be found |
Three domains of life |
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What are the two main types of transposable elements |
Transposons Insertion sequences |
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What is an insertion sequence |
Around 100 nucleotides long Inverted repeats 10-50 bp Only gene is for the transposase Found in plasmid and chromosome of bacteria and archaea In some bacteriophages |
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What is a transposon |
Moves any DNA between inverted repeats Insertion of transposable element generates a duplicate target sequence May include antibiotic resistance (Tn5 and Tn10) |
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What are the two types of transposition |
Conservative and replicative |
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What is conservative transposition |
Transposon is excused from one location and reinserted at a second location number of transposons stays consistent |
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What is replicative transposition |
A new copy of transposon is produced and inserted at a second location number of transposons present doubles |
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How do you make mutants with transposons |
transposons with antibiotic resistance used transposons is on a plasmid that can’t be replicated in cell- temperature sensitive replicon Cells capable of growing on a lecture medium likely acquired transposons Screened for miss of function to determine insertion site Mutated gene tagged with resistance marker |
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What does CRISPR stand for |
Clustered regulatory interspaced short palindromic repeated |
