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42 Cards in this Set

  • Front
  • Back
Basic microbial nutritional requirements.
1. 12-13 carbon precursor
2. electrons that are already high energy or can be energized, or energy source for low energy electrons.
3. movement of high energy electrons leads to ATP production and/or proton motive force.
4. sources of nitrogen, sulfur, phosphorus, iron and some other minerals to make all cellular building blocks from precursors.
Classification of microbes by carbon source
1. Autotrophs - CO2 is sole or principal biosynthetic carbon source
2. Heterotrophs - carbons from other molecules.
Classification of microbes by energy source
1. Phototrophs - energy from light
2. Chemotrophs - oxidation of organic or inorganic compounds
Classification of microbes by electron source
1. Lithotrophs - reduced inorganic molecules
2. Organotrophs - organic molecules
Carbon source, energy source, and electron source for: Photolithoautotroph
Carbon source: CO2
Energy source: light
Electron source: inorganic electrons
Carbon source, energy source, and electron source for:
Photoorganoheterotroph
Carbon source: Organic Carbon
Energy source: light
Electron source: Organic electrons
Carbon source, energy source, and electron source for:
Chemolithoautotroph
Carbon source: CO2
Energy source: Inorganic chemicals
Electron source: Inorganic electrons
Carbon source, energy source, and electron source for:
Chemolithoheterotroph
Carbon source: Organic Carbon
Energy source: Inorganic chemicals
Electron source: Inorganic electrons
Carbon source, energy source, and electron source for:
Chemoorganoheterotroph
Carbon source: Organic Carbon
Energy source: Organic chemicals
Electron source: Organic electrons
Why do prokaryotes have transport systems?
Because the cytoplasm is impermeable except to small gas molecules.
What is active transport?
A transport system that moves solutes into the cell against a concentration gradient. Requires an energy source.
Types of prokaryotic active transport systems.
1. Gradient-driven systems
2. ABC systems
3. Group Translocation systems (PTS or phosphotransferase systems)
What is facilitated Diffusion?
(passively driven channel transport) when a membrane changes conformation after taking in molecules to bring them inside the cell and vice versa. Not a major PTS because it requires a high concentration environment outside of the cell.
Explain gradient driven active transport.
When H+ is outside of the cell. It passes into the cell releasing Na+ outside of the cell. Na+ or H+ binds to a complex, changes the binding site to allow sugar or amino acid to bind. It then takes both particles inside the cell.
How does gradient driven active transport get the gradients?
Cells use electron transfers to generate the gradients (respiration) and then use them for active transport.
Explain symport and antiport.
In gradient-driven active transport, symport is when H+ or Na+ and the solute move into the cell together.
Antiport is when H+ and a cation are transferred in opposite directions.
What cannot generate ion gradients?
Fermenting microbes.
What does ABC transport stand for?
ATP Binding Casette
What is the driving force of ABC transport and what is transported?
1. ATP drives this reaction
2. sugars, amino acids, and many other things.
Explain ABC transport.
Where you have a complex in the cytoplasmic membrane and a solute-binding protein (periplasmic binding protein) that attaches to the complex. ATP is hydrolyzed and the sbp releases the substrate to be brought into the cell.
Other names for Group Translocation
phosphoenolpyruvate sugar phosphotransferase (or PTS)
Explain Group Translocation
You start with PEP it gets phosphorylated and transfers it's P to E1. This is repeated for E1 and HPr. It then gives the P to IIA, the specific sugar complex. It then gives it to IIB which then gives the P to the specific sugar and it goes into the IIC channel. The phosphorylated sugar can't come back through the channel.
Who uses Group Translocation the most?
The fermentative bacteria that can't use gradient driven active transport.
Microbial growth refers to
the measurement of numbers of cells within a population, not the growth of the organism.
Petroff-Hausser (counting chamber) method
direct method to count cells by using a microscope to count indiviual cells.
Plating Techniques
count cells by letting them form a colony.
Spectrophotometer
-measures total concentration of cell mass by assessing light scattering.
-used when a culture must be manipulated at a given cell density during its growth.
-both live and dead cells scatter light (bad)
Explain Petroff-Hausser Counting Chamber method
-microbes can be stained prior to counting
-requires special microscope and slides
-immediate answers
-live and dead microbes counted (bad)
-can differentiate between size & shape
Explain the Dilute and plate technique.
-count live cells only
-Takes a lot of time
-usually used to verify other techniques
-Mostly used for antibiotic type experiments
Axis names of growth curve chart.
Log (cells) vs. time
Phases of a growth chart.
1. Lag phase - when new cultures are inoculated from non-growing cells (takes awhile to start growing).
2. Log phase - phase of growth, generates the growth rates.
3. Stationary phase - approx. 10^9; when cells stop dividing or growth is balanced by death.
4. Death phase - only in dilute and plate method.
Environmental Growth factors that influence growth
pressure, O2 levels, temperature, pH, osmotic concentration,
osmotolerant
able to grow over wide ranges of water activity
halophile
requires high levels of sodium chloride, usually above .2M
barophile
growth it more rapid at thigh pressures
pyschrophile
0 -15 degrees
pyschotroph
can grow at 0-7 degrees, but optimum at 20-30 degrees.
Life likely evolved at....
higher temperatures, therefore, thermophiles.
Enzymes and Proteins when comparing microbial life at thermal extremes.
They are mostly the same and they react very similar. Only a few amino acid differences allow thermophiles to remain folded at high temps. This is due to higher number of specific ionic bonds (replacing hydrogen bonds).
Two reasons the Cytoplasmic membranes help thermophiles.
1. CM's have lipids high in saturated fatty acids in thermophilic bacteria.
2. C40 units ether linked to glycerol phosphate are used by hyperthermophiles.
What is special about hypothermophiles DNA?
Instead of negatively wound DNA they have positively supercoiled DNA.
Pyschrophiles have cytoplasmic membranes with....
higher numbers of polyunsaturated fatty acids.