CMMB 343 midterm 1 Flashcards
what are some problems for cells at low temp?
proteins, membrane, DNA, RNA all too rigid
what are some solutions to low temp problems for cells?
increase membrane fluidity, decrease RNA stability (less GC), increase flexibility of enzymes
Almost all cultured ?? are sulfur or hydrogen-oxidizing.
hyperthermophiles
what is different between Archaea membranes and Eukarya/Bacteria membranes?
Archaea have isoprene chains and are bound to ether linkages while E/B have fatty acid tails bound with ester linkages
what are the major functions of cell membrane?
- Cell’s permeability barrier
- Anchors key proteins
- Major role in energy conservation and consumption
how many bacteria cells are there in 1 g of soil? what % of biomass do they account for on Earth?
1,000,000,000
20-50%
Conan the bacterium
- Deinococcus radiodurans
- most radiation resistant organism (>1000 times dose that will kill humans)
- multiple copies of its genome, switches which one is in use while others repair
Louis Pastuer
- Discovered that alcoholic fermentation was a biologically mediated process
– Disproved theory of spontaneous generation
– Led to the development of aseptic technique
– Developed early vaccines (rabies)
Robert Koch
– Demonstrated the link between
microbes and infectious diseases (CAUSATIVE AGENTS of anthrax and tuberculosis)
– Koch’s postulates
– Developed techniques (solid media) for obtaining pure cultures of microbes, some still used today (1st to use agar plates)
– Awarded Nobel Prize for Physiology and Medicine in 1905
Sergei Winogradsky
- father of microbio
- W column
- proposed chemolithotrophy (oxidation of inorganic compounds to get energy, autotrophy - carbon from CO2)
- linked specific bacteria to specific biogeochemical transformations (N and S cycles)
Koch’s postulates
a set of criteria for proving that a given microorganism causes a disease
W. column: what gradients exist?
bottom-up = sulfide concentration (highest at bottom)
top-down = oxyfgen concentration (highest at top, more areboic bacteria - cyanobacteria at very top layer)
father of bacterial taxonomy? what did the OG taxonomy include?
Ferdinand Cohn
4 groups based on shape: cocci, rod, sphere, filamentous
chemolithotroph
energy source = inorganic chemicals (H2, H2S, NH4+, etc)
chemoorganotroph
energy source = organic chemicals (sugars, proteins, etc)
heterotroph
carbon source = organic chemicals
autotroph
c source = CO2
early tree of life made by? based on?
Haeckel, based on belief that evolution strives towards higher complexity
Universal tree of life: newest version
by Carl Woese who used DNA not just morphology, used ribosomal RNA since every living thing has ribosomes
why is important to include sucrose in cell suspensions?
sucrose lowers the water activity of the cell suspension, preventing too much water from leaving the cells causing lysis
if the water activity is higher inside the cell than in the solution, what will happen?
water moves out of cell
what is the salt-in strategy?
- cells will accumulate KCl
- cheaper method energetically
- salts damage enzymes tho
- mostly Archaea
what is the compatible solutes strategy?
- accumulate organic solutes (the cells make them)
- more expensive
- Bacteria and Eukarya
- no damage to enzymes
plasmolysis
cell shrivels from negative pressure from water leaving the cell, cell wall is ripped off
water moves from areas of ? water activity to ? water acitivity
high to low water activity (aw)
high solute content = ? aw
low water activity
aerobes
need O2 for respiration
microaerophiles
need O2, but at low levels (less than atmospheric levels), have some enzymes that are damaged by O2
facultative anaerobes
can respire O2, but don’t require it
aerotolerant anaerobes
don’t respire O2, but are NOT damaged by it (has no effect on them)
obligate anaerobes
don’t respire O2 and ARE damaged by it (highly sensitive)
what is something that can be used to determine which of the 5 oxygen related species and organism is?
thioglycolate broth
a complex medium that separates microbes based on O2 requirements
why is oxygen toxic?
exposure to O2 yeilds toxic byproducts:
- superoxide (O2-)
- hydrogen peroxide (H2O2)
- hydroxyl radical (OH.) which is the WORST
what do these do?
1. catalase
2. peroxidase
3. superoxide dismutase
4. superoxide dismutase/catalse combo
5. superoxide reductase
- 2H2O2 –> 2H20 + O2
(gets rid of hyd peroxide) - H2O2 + NADH –> 2H20
(rid of hyd peroxide) - 2 O2- –> H2O2
(rid of superoxide, but makes hydrogen peroxide, now need 1 or 2) - 4O2- –> 2H2O + 3O2
- reduces O2- to H2O2, oxidizes rubredoxin in process
gram positive cell
- thick peptidoglycan cell wall
- one (innner) membrane
- purple on gram stain
gram-negative cell
- outer membrane
- periplasm (contains thin peptidoglycan cell wall)
- cytoplasmic (inner) membrane
- pink/red on gram stain
True or false: Membranes do not allow the passage of ions, sugars or amino acids (large or strongly polar molecules). These must be transported.
true
are saturated or unsaturated fatty acid tails preferred for psychrophiles?
unsaturated, the double bonds in the tails don’t pack as tightly, make the membrane more flexible which is needed in colder temps
thermophiles prefer (saturated/unsaturated) fatty acid tails in their membranes?
saturated
?? lipids lack fatty acids, but have isoprenes instead
Archaeal
? can exist as lipid monolayers, bilayers, or mix of both
archaeal membranes
why are monolayers beneficial to certain Archaea?
less membrane fluidity, can survive in hotter temps (thermophiles)
are ether or ester linkages more stable?
ether (Archaea)
explain the 3 transport protein mechanisms
- simple transport: transmembrane transport protein
- group translocation: series of proteins
- ABC system: 3 components, bing protein, ATP-hydrolyzing protein, transmembrane prot
most ? are Gram neg
bacteria (not Bacteria)
gram neg or pos are often pathogens?
GRAM POS
are g - or + better halophiles? why?
gram pos cells are better halophiles, have and increased internal pressure,
do gram neg or pos cells have crosslinks btw DAP and D-alanine carboxyls on adjacent glycan strands
gram-negative
teichoic acids only found in? what do they do?
the peptide wall of gram-positive cells
they are antigenic (kill bacteria), maintain cell shape and porosity of wall, capture cations (Ca2+, Mg2+), phosphate reservoir, regulate cell wall turnover (autolysins)
periplasm
space btw cytoplasmic and outer membranes in gram neg
what 3 keys structures make up Lipopolysaccharides?
- O-specific polysaccharide
- core polysaccharide
- Lipid A (endotoxin)
the cell wall and membrane together make up?
cell envelope
What is transglycosylase role in peptidoglycan synthesis?
Peptidoglycan synthesis requires two activities: transglycosylase (TG) to polymerize the glycan chains and transpeptidase (TP) to catalyze peptide cross-linking between two adjacent glycan chains.
how come penicillin can be used in humans to target bacteria?
eukaryotes don’t have peptidoglycan, but bacteria do and autolysin activity continues causing autolysis of bacteria cell
what does penicillin do?
inhibits transpeptidase activity - leads to cell death
beta-lactamase
provides bacterial cells with antibiotic resistance (ex it becomes resistant to penicillin)
what can freely pass through the cytoplasmic membrane?
dissolved O2 and simple alcohols
LPS (Lipopolysaccharides are unique to?
outer membrane of gram neg bacteria
bacterial cells that move can only sense a gradient by identifying ? changes and NOT ? differences `
they sense temporal changes
NOT spatial changes
cuz they r small
in general prokaryotes or eukaryotes grow in higher temps?
prokaryotes
are phototrophic or non phototrophic organisms able to grow at higher temps?
NON-PHOTOTROPHIC
peptide INTERBRIDGE is present in?
gram pos Bacteria
the presence of diglycerol tetraethers in some archaea indicate what kind of cell membrane?
monolayer
The person who described the “wee animalcules” was
Antoni van Leuuwenhook
_______ are charged molecules that are partially responsible for the ________ charge of the Gram-positive bacterial cell surface.
teichoic acids
negative
Which of the following is an example of a cultured marine chemoorganotrophic bacterium that contains proteorhodopsin and is a member of the SAR11 clade?
pelagibacter
what is ANI and what is it most commonly used for?
average nucleotide identity, used for genome sequencing
what inhibits the FtsZ ring?
MinCD
endospores are only in gram ?
positive
