Term
| What is auxotrophy? Describe how it relates to the Ames test? |
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Definition
-When an essential compound cannot be synthesized
-The Ames test uses Salmonella typhimurium with a histidine synthesis error that makes it only able to grow on medium with his
-The strain is incubated with suspected mutagens to see if they will revert back to wildtype and grow. |
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Term
| What is the difference between an absolute and conditional mutation in bacteria? |
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Definition
-The absolute will always display it's altered phenotype, while the conditional will only show under certain conditions
-E.g. Heat sensitivity mutation; fine until temp increases |
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Term
| How does the fluctuation test work? |
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Definition
-First we do a control and inoculate, from a single flask of bacteria, a bunch of agar plates containing phage
-For the actual test, we inoculate many test tubes with the bacteria and let it culture
-After they grow we again inoculate the phage-agar and look for variation in growth
-Basically, it tests the mutation/evolution of bacteria by natural means (the fluctuation)
-Is also called the Luria-Delbruck experiment |
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Term
| Diff between transition and transversion mutation? |
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Definition
-Transition is purine--->other purine, or pyr-->pyr
-Transversion is purine<--->pyramidine |
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Term
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Definition
| -DNA cut out, flipped, and put back in |
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Term
| What are intragenic and extragenic suppression? Give an example? |
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Definition
-Intragenic suppression is two mutations within a single gene that cancel each other out; like suppression of a frameshift mutation by adding a base in elsewhere
-Extragenic suppression is a mutation other than the original mutated gene that functions to suppress it; like suppression of a nonsense mutation by altering the anticodon of tRNA |
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Term
| Name the common mutagens/types (8)? |
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Definition
1. Nitrous acid
2. Hydroxylamine
3. Alkylating agents
4. Base analogs
5. Intercalating agents
6. UV light
7. Ionizing radiation
8. Genetic elements |
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Term
| How does nitrous acid mutate? What is the result? |
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Definition
-It causes oxidative deamination
-Cytosine--->uracil
-Adenine--->hypoxanthine
-Guanine--->xanthine
-The end result is *transition mutations |
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Term
| How does hydroxylamine work? What is the overall effect |
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Definition
-It modifies C to pair with A (instead of G)
-Overall we get a GC--->AT transition
-GC--->AC'--->AT |
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Term
| How do alkylating agents work? |
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Definition
-Modifies G to pair with T
-Again, has the effect of changing GC to AT |
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Term
| What do base analogs cause? What are examples of them? |
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Definition
-They can cause GC<--->AT (both ways)
-5-bromouracil, adenine in the imino configuration |
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Term
| What do intercalating agents cause? |
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Definition
| -They basically insert themselves in the ladder and cause addition and deletion errors; i.e. *frameshift mutations |
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Term
| What do UV light and ionizing radiation do? |
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Definition
-UV makes T dimers
-Radiation causes free radical generation causing strand breaks and deletions |
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Term
| What are genetic mutagens? |
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Definition
-Mutator genes and transposable elements (*transposons)
-Purposely cause mutation |
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