Bacterial Genetics

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inability to synthesize an essential metabolite

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auxotrophy

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the wildtype of a auxotroph which can grow on minimal medium (with carbon source) is called

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prototroph

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an assay which orders genes in a biosynthetic pathway

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Cross feeding

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how does isolation w/penecilin work?

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auxotrophic mutants do not grow in medium and penicillin

prototrophs grow but then are killed

(penecillin only kills growing cells)

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genetic recombination which requires extensive DNA homology

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general recombination

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genetic recombination which requires small region of homology

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site specific

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genetic recompbination which requires no homology and occurs at low frequency

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illegitamate recombination

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integration of lysogenic bacteriophage such as lambda is an example of what kind of recombination

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site specific

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random integration of transposons is an example of

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illegitamate recombination

IS inits are part of a transposon and the simplist transposon is just IS units

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when you isolate a bunch of mutants with the same phenotype - this test can help you determine # of individual genetic elements

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complementation

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if genetic elements are on diff genes then will complementation occur

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yet - but not when on same gene. (if on same genes - a defect in one is not fixed by the presence of the other

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2 mechanisms which result in antibiotic resistance

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1. mutation to antibiotic resistance
2. acquisition of drug resistance by RTF plasmid

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when mutant phenotype is present only under certain conditions

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conditional mutant

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bacteriophage consists of

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nucleic acid and protein coat

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what part of the bacteriphage determines the type of bacteria it will infect

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protein coat

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how do you grow and assay bacterialphage

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1. grown in actively growing bacterial culture
2. lysis of bacteria - release of phage
3. Quantify by plaque assay
4. plaques by diff phage have diff morphology (contain several million phages)

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clear plaques characterize what life cycle

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lytic

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a kinetic analysis of phage reproduction shows that only phage nucleic acid enters cell is called
viral compenents are synthsized and assmeled late in infection

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one step growth curve

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temporate phages produce what plaques

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turbid

temporate phage can follow either the lytic or lysofenic pathway (DNA is incorporated in host chromosome, phage genome is propagated as bacteria divide)

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C1 repressor

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represses lytic phase

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degrades infecting foreign DNA (protection from bacteriophage)

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restriction enzymes

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modifys self DNA (protection from restriction enzymes)

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modyfying enzymes

recognizes certain palindrome sequences. e.g Eco RI methylates

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mobile genetic elements that integrate into bacterial chromosome and can jump from one location in DNA to another

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Transposons

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the simplist transposon consists of only

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IS (insertion sequences) w/ the help of transposase enzyme

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pure IS sequence movement is an e.g of what kind of recombination

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Illegitimate (non-homologous)

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uptake of naked DNA from another bacteria

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transformation

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what kind of recombination takes place with transformaiton

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DNA binds and enters cell where homologous recombination occurs

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the ability to transform is called

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competence

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used for linkage mapping mainly recombinating DNA Plasmids

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transformation

(the ability to uptake naked bacterial DNA - type of homologous recombination)

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bacterial DNA is moved from one bacteria to another by a virus

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transduction

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kind of transductio where phage particle contains ONLY host DNA

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generalized

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kind of transduction where the DNA is derived from the host and the phage

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specialized transduction

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type of transduction where
temperate phage integrates into host cell chromosome at specific local

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specialized transduction

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kind of transduction used to infect auxotoph with the machinery missing

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generalized transduction

(phage ONLY carries DNA from host)

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unequal exchange of genetic info between two parents

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conjugation

sexual reproduction in bacteria mating mediated by special class of plasmids called F plasmids

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in conjugation the donr has the plasmid and is deemed

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F+

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a bacteria is said to be "cured" when

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it is converted from F+ to F-

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Hfr

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High frequency transfer
extrachromosomal F plasmid integrates into bacterial chormosome

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F'

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when nearby chromosomal genes are carried with F

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the property that each amino acid is specified by more than one codon. one reason why mutations are sometimes silent

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degeneracy

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bacteriocidins

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plasmids that encode antibiotics

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a rescue of the phenotype of a mutant incapable of making a certain protein by supplying the protein to the mutant organism.
e.g introduction of a copy of the wild type gene into the organism

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complementation

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copy number

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the number of copies of plasmid in a cell. controlled by a represor of plasmid replication

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different plasmids control copy number with specific repressors. two very similar plasmids will be unable to coexist in the same cell due to the similarity of their repressors and can be grouped into the same

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incompatibility group

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an extrachromosomal DNA element that is capable of autonomous DNA replication: a plasmid

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episome

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a kind og F factor that contains some host chromosomal genes - results from the insertion of the F into the host chromosome and susequent imprecise excisiont of the plasmid, thus taking some chromosomal genes with it

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F' factor

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the transfer of DNA from one bacterium to another mediated by a specific type of bacteriophage

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generalized transduction

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plasmids integrating into bacterial genome with the help of IS units do this via what kind of recombination

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homologous

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a resistance plasmid RTF is often flanked by IS and can there for be transmitted to another RTF by

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transposition

this is the mechanism by which multiple resistance arises

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specific sequences that are involved in transposition. encode a transposas and mediate illegitimate recombination

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IS element

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a theory that genetic changes are induced by enviromental changes

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lamarkism

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lambda

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example of temperate bacteriophage

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lysogen

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a prophage

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medium that contains a single carbon source, a nitrogen source, and a phosphate source.

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minimal medium - only will support the growth of prototrophs

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a clearing in a lawn of bacteria on agar dish caused by single bacteriophage undergoing replication and infectin and lysing neighboring cells

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plaque

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a chromosomally integrated genome of a temperate bacteriophage

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prophage

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a conjugative plasmid that carrieds one or more drug resistance genes

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R factor

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a mutation that reverse a mutation phenotype to the wild type

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revertant

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DNA replication; a parental DNA molecule is replicated into two molecules each with one strand derived from the parent and one newly synthesized strand

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semiconservative replication

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integration of a temperate bacteriophage into a specific location in host bacterial chromosome is an eg of

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site-specific recombination

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true revertant

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reversal ofo original mutation

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supressor revertant

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restores wild type but occurs at a second site

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the lederberg experiment showed what

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resistant mutants appeared spontaneously then were selected for w/ antibiotic treatment