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30 Cards in this Set
- Front
- Back
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What are selectable mutations?
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mutations giving a growth advantage like antibiotic resistance
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What are non selectable mutations?
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mutations having neither an advantage nor a disadvantage, detected by screening
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What types of organism do replica plating identify?
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Auxotrophs: cells with a nutritional requirement for growth
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What are induced mutations?
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mutations made deliberately or as a result of env. influence (ex. exposure to natural radiation)
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What are spontaneous mutations?
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mutations occurring without external intervention, like mistakes in DNA replication/repair
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What is genetic engineering?
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involves introduction of specific mutations (site-directed mutagenesis)
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What is reversion?
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Alteration in DNA that reverses the effects of a prior mutation
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What is a revertant? What are the two types?
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strain in which original phenotype is restored
1) Same site revertant: mutation at same site as original mutation, reproduced WT 2) Second site revertant |
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What is a second site revertant
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Mutation is at a different site in DNA, but still restores WT Phenotype.
Called a suppressor mutation |
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which genome DNA virus/RNA virus has a higher error rate?
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RNA genome
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What are mutagens?
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Chemical, physical or biological agents that increase mutation rates
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What are the different classes of chemical mutagens?
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1) Nucleotide base analogs (resemble nucleotides, DNA can't bp correctly)
2) Chemical mutagens-induce chemical modifications 3) Chemical mutagens causing frameshift mutation |
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What is an example of a chemical mutagen inducing chemical modification?
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Nitrosoguanidine
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What is an example of Chemical mutagens causing frameshift mutation
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Intercalating agents like acridines
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What forms of radiation are mutagenic?
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1) Non-ionizing (UV): purines & Pyrimidines absorb UV, produce dimers
2) Ionizing (X-ray, cosmic ray, gamma ray): ionize water and produce free radicals damaging cells |
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What type of radiation uses higher energy?
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Ionizing radiation (X-ray, cosmic ray, gamma ray)
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What are three types of DNA repair systems?
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1) Direct reversal: mutated base is recognized by enzymes, repaired without referring to other strand.
2) Repair of ss damage: damaged DNA removed and repaired using opp. strand as template 3)Repair of ds break: Require more error-prone mechanism--> If break can't be repaired-cant replicate-die |
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What is the Ames test?
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Detects an increase in mutations in a bacterial strain treated with suspected mutagen which are usually carcinogenic
Reversion of auxotrophic strains: revertants can grow on minimal medium, colonies can be counted |
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What is recombination
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Physical exchange of DNA between genetic elements (Chromosomes, plasmids, virus, free DNA fragment)
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What is homologous recombination?
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genetic exchange between homologous DNA regions from 2 different sources- homologous DNA regions have a common ancestor, contain similar seq and genes
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What is a competent?
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cells capable of taking up DNA and being transformed.
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What conditions are needed for a cell to become competent?
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Some bacteria are naturally competent. Others need to be treated with: calcium, cold temp, electroporation (electric voltage spike)
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What is transduction?
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Transfer of DNA from one cell to another by a bacteriophage (virus)
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What are two types of transduction?
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1) Generalized: DNA from any portion of the host genome is packaged inside vision
2) Specialized: DNA from a specific region of host chromosome is integrated directly into virus genome. |
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What types of viruses are involved with generalized transduction?
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Both temperate and virulent
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What types of viruses are capable of specialized transduction?
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Temperate virus: DNA of temperate virus excises incorrectly, takes adjacent host genes along
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What is bacterial conjugation?
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Mechanism of genetic transfer involving cell to cell contact.
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What does the donor cell and recipient cell contain in bacterial conjugation?
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Donor=Contains Conjugative plasmid (F+)
Recipient=No conjugative plasmid |
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What are essential features of conjugation?
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1) Sex pillus (produced by donor cell, encoded by F+ plasmid)
2) DNA synthesis by rolling circle replication necessary for DNA transfer |
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What features does the F plasmid contain?
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1)Circular DNA
2) Genes regulating DNA replication 3) Transposable elements that allow plasmid to integrate into host chromosome 4) Tra genes that encode transfer functions |
