OOTW Flashcards
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)
