1
Q
Vibrio Fischeri
A
- squid symbiont
- uses luciferase enzyme
- produces light only at high cell density
- “quorum sensing”
- squid feeds bacteria and bacteria emit light for squid to use for counter-illumination (invisible to prey)
- chemical recognition between squid and bacteria
2
Q
Epulopiscium fishelsoni
A
- large bacterium that looked like it had organelles (thought it was a eukaryote)
- 16S rRNA sequening showed it’s a bacterium
- cannot culture in lab
- unusual cell division: daughter cells grow inside mother cell and burst out, killing mother cell
3
Q
Escherichia coli
A
- E. coli K12: human gut microbe that’s harmless
- E. coli O157:H7: pathogen infected with a phage that causes it to form pili and a toxin
- 16S rRNA identical, but chromosomes 25% diff
4
Q
Mycoplasma pneumoniae
A
- smallest bacterial genome
- no peptidoglycan
- may substitute with cholesterol or endoskeleton
- cholesterol used to buffer membrane fluidity in euks; increase or decrease molecular space
5
Q
Mycobacterium tuberculosis
A
- “consumption”
- becomes dormant in the body
- unusual cell architecture: two EPS layers with a thick, waxy cuticle (mycolic acid lipid layer) between them; membrane (innermost), peptidoglycan, EPS, mycolic acid, capsule (EPS)
- resistant to antibiotics, acid/base, osmotic damage, oxygen radicals, immune system
- slow growth: all of the defenses reduce diffusion and lower growth rate
6
Q
Magnetospirillum magnetotacticum
A
- magnetosomes: storage granules composed of magnetite; membrane invaginations (not completely surrounded by membrane); mamK filament organizes magnetosomes inside of cell
- used to orient motility in a magnetic field
- find optimal oxygen concentrations
7
Q
Caulobacter crescentus
A
- environmental bacterium
- during nutrient starvation, stalk elongates to increase SA
- strongest glue “holdfast” (EPS)
- asymmetric division: each division produces a swimmer (flagellum, cell cycle arrested) and a stalked cell (holdfast, actively dividing)
- the same stalk cell produces multiple swimmers
8
Q
Deinococcus radiodurans
A
- radiation resistant (“spam”)
- multiple chromosomes/cell
- compacted nucleoid into torus
- radiation creates radicals that break the chromosome into pieces. Multiple chromosomes provide many copies to correctly reassemble. Toroidal nucleoid stucture may preserve order of the pieces for rapid reassembly.
- desiccation resistant
9
Q
Bdellovibrio bacteriovorus
A
- intracellular predator of gram neg bacteria
- pulls into the periplasm with type IV pili
- solidifies host outer membrane
- turns prey into growth chamber
- (1) infects periplasm (2) elongates and solidifies host outer membrane (3) doesn’t use binary fission, multiple simultaneous divisions (4) host lysis and release
- lacks MinCDE
10
Q
Chlamydia trachomatis
A
- intracellular pathogen (grows inside human cells)
- lacks FtsZ
- cannot make own ATP; steals ATP from host (ATP/ADP antiporter)
- cannot be cultured in lab
- alternates between two cell types: EB (elementary body, growth arrested/dormant) and RB (reticulate body, growing/toxic form)
11
Q
Clostridium acetobutylicum
A
- endospore forming, anaerobe
- flexible heterotroph: can eat unusual substrates (TNT)
- ferments sugars to acetone and butanol
- improved fermentation by heat-shocking to select for spore-formers
- uses sugar substrate then produces pyruvate through EMP pathway which is converted to acetone and butanol through fermentation
12
Q
Geobacter metallireducens
A
- consumes sugars + oil-based pollutants
- respires metals (Fe, U, Tc)
- bioremediation
- respires insoluble metals
- pili conduct electrons outside cell “nanowires”
- anaerobic respiration (NADH to NAD+ and U6+ to U4+)
- nanowire allows respiration of insoluble metals; a conductive pilus ancored in the plasma membrane and part of the ETC
13
Q
Halobacterium salinarum
A
- archeon
- halophilic
- desiccation/radiation resistant
- simple photosystem: bacteriorhodopsin
- simple proton pump directly coupled to light absorption and does not use ETC
- requires photo-pigment cofactor retinal
14
Q
Sinorhizobium meliloti
A
- legume symbiont
- fixes nitrogen in plant nodules
- bacteriod doesn’t grow
- plant gets nitrogen, bacterium gets carbon
- cell-cell communication: (1) plant root sends flavanoid signal to attract sinorhizobium and (2) sino sends signal “Nod factor” back to plant; signals are specific for both plant and bacterium (ensures proper recognition between partners)
nodulation: (3) infection thread (4) bacteroid formation - leghemoglobin: delivers bound oxygen to bacteroid; controls oxygen so as not to destor nitrogenase
- bacteroids inside plant make rhizopines that crossfeed sino growing outside of the plant
- rhizopines: carbon, nitrogen, and energy source that only sino on the outside can eat (crossfeeding)
15
Q
Bacillus subtilis
A
- produces proteases, riboflavin, fungicide
- powerful genetic system
- “competent” takes up free DNA from environment
- sporulation, cascade of sigma factors
- spore is metabolically dormant, resistant to heat/desiccation/radiation
- cascade of sigma factors: sigma A –> sigma H (starvation) –> sigma F (early forespore genes) –) sigma E (early mothercell genes) –> sigma G (late forespore genes) –> sigma K (late mothercell genes)
16
Q
Fremyella diplosiphon
A
- cyanobacterium
- fixes carbon and nitrogen
- heterocysts protect nitrogenase
- oxygenic phototrophy
- makes gas vesicles
- chromatic acclimation: fremyella adjusts antenna proteins to match light color (in green light, makes green absorbing phycobilisomes & in red, makes red); controlled by two component system (RcaE histidint kinase and RcaC response regulator)
- in green light, RcaC/E does nothing (green is default); in red, RcaC is phosphorylated, binds to DNA, activates red pigments, represses green pigments
- pigment optimization: water acts like a prism, fremyella “sees” different colored light in water, some colors penetrate farther in water than others, pigments are adjusted to match light
17
Q
Agrobacterium tumefaciens
A
plant pathogen
- creates tumors
- transfers Ti plasmid to plant by conjugation
- Ti plasmid directs production of growth hormone and octopine synthesis (similar to rhizopine in sino; carbon, nitrogen, energy rich molecule)
- (1) tranfer Ti plasmid to plant by conjugation (2) the Ti plasmid recombined into the plant chromosome (3) plant expresses Ti genes (growth hormones to multiply, octopine biosynthesis genes) (4) bacterium feeds on the octopines
18
Q
Borrelia burgdorferi
A
- lyme disease (tick-bourne)
- spirochete
- endoflagellum
- rotates cell body to push through viscous environment
- requires no iron
- has linear chromosome
19
Q
Myxococcus xanthus
A
- gliding motility in biofilm
- only eats amino acids
- predator of other bacteria (secretes digestive enzymes, share nutrients from prey)
- multicellular fruiting bodies
- sporulation
- makes antibiotics and anti-cancer drugs
20
Q
Streptococcus pneumoniae
A
- infects lungs
- causes deaths with flu as secondary infection
- natural transformation system: makes Com machinery
- antigenic variation, 90 capsule structures in species
- mimicry: some capsules look like host cell sugars
- griffith transformation experiment: (1) no cappsule = harmless (2) w/ capsule = virulent (3) dead w/ capsule = harmless (4) dead capsule strain mixed with live capsuleless strain = virulent; capsule (required for virulence) can be passed to avirulent strain
- avery transformation experiment: capsule genes transferred to avirulent strain during coinfection by natural competemce (transformation)
21
Q
Yersinia pestis
A
- bubonic plague
- wide variety of virulence factors encoded on plasmids: pMT1 (encodes pili), pPCP1 (encodes protease), pCD1 (encodes toxins and type III secretion machine)
- injects toxins directly into host: type III secretion system; minimizes diffusion of toxins and toxins are in the same space as their targets; antigens on toxins are never exposed to immune system
22
Q
Streptomyces coelicolor
A
linear chromosome
- hyphal growth, cell division is rare
- multiple chromosomes per cell
- developmental cycle
- sporulation
- polyketide antibiotics
- (1) grows into substrate (2) during starvation it secretes antibiotics and hydrophobin (3) grows into the air and forms chains of spores
- 75% of world’s antibiotics come from streptomyces; each species makes multiple, unique antibiotics
- specializes in polyketide antibiotics; look very complex but are actually variations on oner another; related to fatty acid biosynthesis
23
Q
Methanococcus jannaschii
A
- grows in high pressure and high temps
- strict anaerobe (respires H2 and CO2, converts CO2 ro CH4 and H2 to H+)
- no pseudopeptidoglycan
- plasma membrane with an S-layer
- contains cyclic lipids
- chemolithoautotroph
- methanogen
BIOL-M 250
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