Microbial Genetics I. Structure and function of genes II. Gene expression in bacteria III. Mutation...
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Transcript of Microbial Genetics I. Structure and function of genes II. Gene expression in bacteria III. Mutation...
Microbial GeneticsMicrobial Genetics
I. Structure and function of genesI. Structure and function of genes
II. Gene expression in bacteriaII. Gene expression in bacteria
III. Mutation and variationIII. Mutation and variation
IV. Horizontal gene transfer in bacteriaIV. Horizontal gene transfer in bacteria
Levels at which enzymes can be regulatedLevels at which enzymes can be regulated
In prokaryotes, expression is generally regulated at the level of _____________
In bacteria, genes are organized into operons
In bacteria, genes are organized into operons
OperonOperon -- a cluster of genes whose expression is -- a cluster of genes whose expression is controlled by a single controlled by a single operatoroperator..
OperatorOperator -- a specific region of the DNA at the -- a specific region of the DNA at the initial end of a gene or operon, where a initial end of a gene or operon, where a repressor repressor proteinprotein binds and _______________ mRNA binds and _______________ mRNA synthesis.synthesis.
Repressor proteinRepressor protein -- a regulatory protein that binds -- a regulatory protein that binds to specific sites on DNA and blocks to specific sites on DNA and blocks ______________________ .______________________ .
One method of gene regulation: enzyme _________________
One method of gene regulation: enzyme _________________
Enzyme induction, (cont.)Enzyme induction, (cont.)
The lac Operon: an example of enzyme _____________
The lac Operon: an example of enzyme _____________
http://esg-www.mit.edu:8001/bio/pge/lac.htmlhttp://esg-www.mit.edu:8001/bio/pge/lac.html
-galactosidase-galactosidase
RepressorRepressor
When lactose is unavailable, the repressor is _____________. It binds to the operator region, blocking the binding of the
___________ ______________________.
When lactose is unavailable, the repressor is _____________. It binds to the operator region, blocking the binding of the
___________ ______________________.
RepressorRepressor
No mRNA and no proteinNo mRNA and no protein
http://esg-www.mit.edu:8001/bio/pge/lac.htmlhttp://esg-www.mit.edu:8001/bio/pge/lac.html
The presence of lactose causes a conformational change in
the repressor, which renders it ________________ to bind the
__________________________
The presence of lactose causes a conformational change in
the repressor, which renders it ________________ to bind the
__________________________
http://esg-www.mit.edu:8001/bio/pge/lac.htmlhttp://esg-www.mit.edu:8001/bio/pge/lac.html
BlockedBlocked
lactoselactose
Review: lac operon without inducer (________________)
Review: lac operon without inducer (________________)
QuickTime™ and aAnimation decompressor
are needed to see this picture.
http://www.biology.arizona.edu/molecular_bio/problem_sets/mol_genetics_of_prokaryotes/02t.html?http://www.biology.arizona.edu/molecular_bio/problem_sets/mol_genetics_of_prokaryotes/02t.html?
Review: lac operon with inducer (lactose)
Review: lac operon with inducer (lactose)
http://www.biology.arizona.edu/molecular_bio/problem_sets/mol_genetics_of_prokaryotes/02t.html?http://www.biology.arizona.edu/molecular_bio/problem_sets/mol_genetics_of_prokaryotes/02t.html?
Text, Fig. 9.21Text, Fig. 9.21
Another method of gene regulation: enzyme ________________
Another method of gene regulation: enzyme ________________
Enzyme repression (cont.)Enzyme repression (cont.)
An example of enzyme repression: the ________________ operon
An example of enzyme repression: the ________________ operon
Review: enzyme inductionReview: enzyme induction
Enzyme induction, (cont.)Enzyme induction, (cont.)
Review: enzyme repressionReview: enzyme repression
Enzyme repression (cont.)Enzyme repression (cont.)
MutationMutation
Any permanent, _______________ change in Any permanent, _______________ change in the genetic information of a cell.the genetic information of a cell.
Types:Types: Point mutationsPoint mutations -- substitution, insertion, or -- substitution, insertion, or
deletion of _______________ or a few basesdeletion of _______________ or a few bases Large insertions or ________________Large insertions or ________________
Point mutations -- effects of substitution
Point mutations -- effects of substitution
Point mutations (cont.) -- insertions and
deletions result in _________________ shifts
Point mutations (cont.) -- insertions and
deletions result in _________________ shifts
Insertions or deletions of large segments of DNA can _________________ a gene (depending on where
the insertion lands)
Insertions or deletions of large segments of DNA can _________________ a gene (depending on where
the insertion lands)
Gene AGene A
Transposable Elements: “_______________ genes”Transposable Elements: “_______________ genes”
Palindromes: Go hang a salami, I'm a lasagna hogPalindromes: Go hang a salami, I'm a lasagna hog
C A T G C C G A C G T C T A C T G A A C G T C A G T C CC A T G C C G A C G T C T A C T G A A C G T C A G T C C
G T A C G G C T G C A G A T G A C T T G C A G T C A G GG T A C G G C T G C A G A T G A C T T G C A G T C A G G
G A C G TG A C G T
T G C A GT G C A GA C G T CA C G T C
C T G C AC T G C A
Transposable elementTransposable element
A man, a plan, a caret, a ban, a myriad, a sum, a lac, a liar, a hoop, a pint, a catalpa, a gas, an oil, a bird, a A man, a plan, a caret, a ban, a myriad, a sum, a lac, a liar, a hoop, a pint, a catalpa, a gas, an oil, a bird, a yell, a vat, a caw, a pax, a wag,a tax, a nay, a ram, a cap, a yam, a gay, a tsar, a wall, a car, a luger, a ward, yell, a vat, a caw, a pax, a wag,a tax, a nay, a ram, a cap, a yam, a gay, a tsar, a wall, a car, a luger, a ward,
a bin, a woman, a vassal, a wolf, a tuna, a nit, a pall, a fret, awatt, a bay, a daub, a tan, a cab, a datum, a a bin, a woman, a vassal, a wolf, a tuna, a nit, a pall, a fret, awatt, a bay, a daub, a tan, a cab, a datum, a gall, a hat, a fag, a zap, a say, a jaw, a lay, a wet, a gallop, a tug, a trot, a trap, a tram, a torr, acaper, a top, a gall, a hat, a fag, a zap, a say, a jaw, a lay, a wet, a gallop, a tug, a trot, a trap, a tram, a torr, acaper, a top, a tonk, a toll, a ball, a fair, a sax, a minim, a tenor, a bass, a passer, a capital, a rut, an amen, a ted, a cabal, a tonk, a toll, a ball, a fair, a sax, a minim, a tenor, a bass, a passer, a capital, a rut, an amen, a ted, a cabal, a
tang, a sun, anass, a maw, a sag, a jam, a dam, a sub, a salt, an axon, a sail, an ad, a wadi, a radian, a tang, a sun, anass, a maw, a sag, a jam, a dam, a sub, a salt, an axon, a sail, an ad, a wadi, a radian, a room, a rood, a rip, a tad, a pariah, a revel, a reel, areed, a pool, a plug, a pin, a peek, a parabola, a dog, a room, a rood, a rip, a tad, a pariah, a revel, a reel, areed, a pool, a plug, a pin, a peek, a parabola, a dog, a pat, a cud, a nu, a fan, a pal, a rum, a nod, an eta, a lag, an eel, a batik, a mug, amot, a nap, a maxim, a pat, a cud, a nu, a fan, a pal, a rum, a nod, an eta, a lag, an eel, a batik, a mug, amot, a nap, a maxim, a
mood, a leek, a grub, a gob, a gel, a drab, a citadel, a total, a cedar, a tap, a gag, a rat, a manor, a bar, a gal, mood, a leek, a grub, a gob, a gel, a drab, a citadel, a total, a cedar, a tap, a gag, a rat, a manor, a bar, a gal, a cola,a pap, a yaw, a tab, a raj, a gab, a nag, a pagan, a bag, a jar, a bat, a way, a papa, a local, a gar, a a cola,a pap, a yaw, a tab, a raj, a gab, a nag, a pagan, a bag, a jar, a bat, a way, a papa, a local, a gar, a
baron, a mat, a rag, a gap, a tar, a decal,a tot, a led, a tic, a bard, a leg, a bog, a burg, a keel, a doom, a mix, baron, a mat, a rag, a gap, a tar, a decal,a tot, a led, a tic, a bard, a leg, a bog, a burg, a keel, a doom, a mix, a map, an atom, a gum, a kit, a baleen, a gala, a ten, a don, a mural, apan, a faun, a ducat, a pagoda, a lob, a map, an atom, a gum, a kit, a baleen, a gala, a ten, a don, a mural, apan, a faun, a ducat, a pagoda, a lob, a rap, a keep, a nip, a gulp, a loop, a deer, a leer, a lever, a hair, a pad, a tapir, a door, a moor, an aid,a raid, a rap, a keep, a nip, a gulp, a loop, a deer, a leer, a lever, a hair, a pad, a tapir, a door, a moor, an aid,a raid,
a wad, an alias, an ox, an atlas, a bus, a madam, a jag, a saw, a mass, an anus, a gnat, a lab, a cadet, an a wad, an alias, an ox, an atlas, a bus, a madam, a jag, a saw, a mass, an anus, a gnat, a lab, a cadet, an em, a natural, a tip, acaress, a pass, a baronet, a minimax, a sari, a fall, a ballot, a knot, a pot, a rep, a carrot, em, a natural, a tip, acaress, a pass, a baronet, a minimax, a sari, a fall, a ballot, a knot, a pot, a rep, a carrot, a mart, a part, a tort, a gut, a poll, a gateway, alaw, a jay, a sap, a zag, a fat, a hall, a gamut, a dab, a can, a a mart, a part, a tort, a gut, a poll, a gateway, alaw, a jay, a sap, a zag, a fat, a hall, a gamut, a dab, a can, a tabu, a day, a batt, a waterfall, a patina, a nut, a flow, a lass, a van, a mow, anib, a draw, a regular, a call, a tabu, a day, a batt, a waterfall, a patina, a nut, a flow, a lass, a van, a mow, anib, a draw, a regular, a call, a
war, a stay, a gam, a yap, a cam, a ray, an ax, a tag, a wax, a paw, a cat, a valley, a drib, a lion, a saga, war, a stay, a gam, a yap, a cam, a ray, an ax, a tag, a wax, a paw, a cat, a valley, a drib, a lion, a saga, aplat, a catnip, a pooh, a rail, a calamus, a dairyman, a bater, a canal--Panama.aplat, a catnip, a pooh, a rail, a calamus, a dairyman, a bater, a canal--Panama.
The mother of all palindromesThe mother of all palindromes
palindromepalindrome
Disruption of a gene due to _______________ of a transposable element
Disruption of a gene due to _______________ of a transposable element
Mutation (cont.)Mutation (cont.)
Causes:Causes:SpontaneousSpontaneous -- due to ________________ -- due to ________________
mistakes or background effectsmistakes or background effects Frequency varies from 1 in ______ to 1 in _______ Frequency varies from 1 in ______ to 1 in _______
depending on organismdepending on organism Bacteria have such short generation times and grow Bacteria have such short generation times and grow
to such high populations that spontaneous mutants to such high populations that spontaneous mutants can be isolated quickly and easilycan be isolated quickly and easily
InducedInduced -- exposure to -- exposure to mutagensmutagens such as such as ______________ or _______________________________ or _________________
Spontaneous (antibiotic) mutantsSpontaneous (antibiotic) mutants
Mutagenesis by electromagnetic radiationMutagenesis by electromagnetic radiation
Chemical mutagenesisChemical mutagenesis
Horizontal gene transfer in bacteriaHorizontal gene transfer in bacteria
ConjugationConjugation -- direct (________________) -- direct (________________)
transfer between bacteriatransfer between bacteria
TransformationTransformation -- uptake of naked, -- uptake of naked,
__________________ DNA (often plasmids)__________________ DNA (often plasmids)
TransductionTransduction -- transfer of DNA from one cell -- transfer of DNA from one cell
to another by a _____________.to another by a _____________.
ConjugationConjugation
A A copycopy of the plasmid is made in of the plasmid is made in the recipient cell, resulting in a the recipient cell, resulting in a
plasmid in each cellplasmid in each cell
Text, Fig. 9.27Text, Fig. 9.27
________________________________________
Donor cell dies and Donor cell dies and lyses, releasing DNAlyses, releasing DNA
The free DNA is The free DNA is taken up by a taken up by a
recipient cell, and recipient cell, and incorporated into incorporated into
its genomeits genome
Griffith’s classic experiment in transformation Fig. 9.28Fig. 9.28
____________________________________
Text, Fig. 9.29Text, Fig. 9.29
How is the DNA incorporated?How is the DNA incorporated?
homologous recombinationhomologous recombination -- -- genetic exchange genetic exchange between (nearly) _________________ DNA sequences between (nearly) _________________ DNA sequences from 2 different sourcesfrom 2 different sources
________________ into chromosome________________ into chromosome
not incorporated into genome at all, but still not incorporated into genome at all, but still functional -- e.g. plasmidsfunctional -- e.g. plasmids