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266 Cards in this Set
- Front
- Back
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What are the three classifications organisms? |
Bacteria, Archaea and Eukarya |
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Bacteria and Archaea are prokaryotes. TRUE OR FALSE |
TRUE |
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All eukaryotes are microbial. TRUE OR FALSE |
FALSE; all prokaryotes are microbial, eukaryotes could be micro- or macro- organisms |
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What is this an image of? |
Prokaryotic cell or E. coli organism |
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What kind of cell is this? |
Eukaryotic cell |
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What do prokaryotic cells lack in comparison to eukaryotic cells? |
Prokaryotic cells lack true, membrane delineated nucleus Prokaryotic cells also lack true, membrane delineated organelles |
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Give an example of an organelle that a eukaryote rather than a prokaryote |
ER, Golgi Apparatus, Mitochondria |
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Plasmids are very common in eukaryotes, rare in prokaryotes. TRUE OR FALSE |
FALSE; Plasmids are very common in prokaryotes, rare in eukaryotes. |
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Ribosomes are smaller in prokaryotes or eukaryotes? |
Eukaryotes |
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What are chromosomes like in prokaryotes? |
Single chromosome that is linear or circular |
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What are chromosomes like in eukaryotes? |
Multiple chromosomes within an organism that are packed |
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Flagella are much smaller, one protein fiber in prokaryotes. TRUE OR FALSE |
TRUE |
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_________________ cells have gas vesicles, never been observed in ____________. |
prokaryotic; eukaryotes |
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What is an absolute requirement for all living organisms? |
Cell membranes |
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Why do some prokaryotes have internal membrane systems? |
-- |
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What does the plasma membrane encompass? |
The cytoplasm |
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What does it mean to be a selectively permeable barrier? |
Some molecules are allowed to pass into or out of the cell Transport systems aid in movement of molecules |
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List the functions of the prokaryotic cell membrane (4) |
Separation of cell from its environment Selectively permeable barrier Location of crucial metabolic processes Detection of and response to chemicals in surroundings with the aid of special receptor molecules in the membrane |
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Give an example of a crucial metabolic process in the cell membrane of prokaryotes
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Respiration |
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What is this an image of? |
Fluid Mosaic Model of Membrane Structure |
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What is the fluid mosaic model of membrane structure? |
Lipid bilayer in which proteins float |
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What are the three main parts of a prokaryotic cell? |
1) Cytoplasmic structure 2) Plasma membrane 3) Additional stuff outside plasma membrane |
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Define lipids |
Naturally occurring, mostly hydrophobic, storage and structural molecules in prokaryotic and eukaryotic cells (fats, oils, waxes, cholesterols) |
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Many, but not all, lipids are derived from __________________. |
fatty acids |
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Why does the prokaryotic cell membrane have folds? |
More surface area means more space for proteins. This allows for more efficient processes and respiration. |
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Describe the structure of a phosphlipid |
Phosphoglcerolipid - lipids are ester bonds of fatty acids and sugar - glycero is the sugar - Phospho is where the third hydroxyl group reacts with PO4 |
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What are the tails of phospholipids made of? |
Long chain fatty acids |
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What are the heads made of for phospholipids? |
PO4 and Ethanolamine |
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In a lipid, 2 fatty acids form ____________ with two of the three hydroxyl groups in glycerol. |
ester bonds |
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Where is the ethanolamine group attached in a lipid? |
One of the oxygens in the phosphate group |
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Which part of a phospholipid is hydrophillic? Which is hydrophobic? Which is polar, which is nonpolar? |
The head is hydrophillic and polar, the tail is hydrophobic and nonpolar |
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What does amphipathic mean? |
The lipids have polar and nonpolar ends |
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Polar ends are insolube in water. TRUE OR FALSE |
FALSE; Nonpolar ends are insolube in water |
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What is the name for other membrane lipids (nonpolar)? |
Hapnoids or hoopanoids |
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Peripheral proteins and integral proteins are _____________ proteins. |
membrane |
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Define peripheral proteins |
Loosely associated with the membane and easily removed |
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Define integral proteins |
Embedded within the membrane and not easily removed |
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Bacterial membranes are highly organized structures that are also asymmetric, flexible, and dynamic. TRUE OR FALSE |
TRUE |
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Plasma membrane infoldings are observed in many photosynthetic bacteria and in prokaryotes with high _______________ activity. |
respiratory |
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What is the structural difference between archaeal lipids and bacterial lipids ? |
Archaeael lipids have a phosphate, sulfur, and sugar as opposed to phosphate, sugar and fatty acid |
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What is the linkage difference between archaeal lipids and bacterial lipids? |
The nonpolar tail of archaeal lipids have an ether linked glyercolipid hydrocarbons as opposed to ester-linked glycerolipid lipid acids |
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List additional nonpolar lipids in Archaea |
Squalene and Tetrahydrosqualene |
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Define dimerize |
form a lipid monolayer plasma membrane |
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Why do lipids dimerize? |
-- |
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List the two common nutrient requirements |
Macroelements Microelements |
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Micronutrients are required in large amounts. TRUE OR FALSE |
FALSE; macronutrients are required in small amount, micronutrients are required in trace amounts |
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Give two examples of Macronutrients |
C and N |
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Give two examples of micronutrients |
Mn and Zn |
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___________ is the backbone of all organic components in cell |
Carbon |
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What two elements are often supplied with the carbon source? |
Hydrogen and oxygen |
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__________ play a role in energy production and reduction of CO2 to form organic molecules. |
Electrons |
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Based on carbon sources, microorganisms could be classified as: |
Heterotrophs or autotrophs |
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Define heterotrophs |
Use organic molecules as carbon sources which often also serve as energy, electron sources |
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Define autotrophs |
Use carbon dioxide as their sole or principal carbon source Must obtain energy, electrons, from other sources |
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Based on energy sources, microorganisms could be classified as: |
Phototrophs or chemotrophs |
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Define phototrophs |
Use light as an energy source |
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Define chemotrophs |
Obtain energy from oxidation of chemical compounds |
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Based on electron sources, microorganisms are classified as: |
Lithotrophs or organotrophs |
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Define liphotrophs |
Use reduced inorganic substances |
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Define organotrophs |
Obtain electrons from organic compounds |
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Nitrogen is needed for syntesis of important molecules. TRUE OR FALSE |
TRUE |
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List two ways N is supplied |
Amino acids, NH4, N2 |
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How is phosphorus usually supplied? |
As inorganic phosphate |
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How is sulfur usually supplied? |
As sulfate via assimilatory sulfate reduction, few require reduced sulfur compounds |
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Define growth factors |
Essential cell components that the cell cannot synthesize and must be supplied by environment if cell is to survive and reproduce |
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List classes of growth factors |
Amino acids Purines and pyramidines Vitamins |
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What are amino acids needed for? |
Protein synthesis |
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What are purines and pyramidines used for? |
Needed for nucleic acid synthesis |
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What are vitamins used for? |
function as enzyme cofactors |
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List practical applications of growth factors |
Use of microorganisms in bioassays to quantify growth factor Industrial production of growth factors by microorganisms |
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List different ways nutrients can enter the cell |
Passive diffusion Facilitated diffusion Active transport Group translocation |
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Define passive diffusion
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Molecules move from region of higher concentration to one of lower concentration because of random thermal agitation |
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What nutrient uptake role does H2O, O2, and CO2 often take? |
Passive diffusion |
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Facilitated diffusion is not energy dependent, like passive diffusion. TRUE OR FALSE |
TRUE |
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Define facilitated diffusion
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Direction of movement is from high conc. to low conc. Size of conc. gradient impacts rate of uptake Uses carrier molecules called permeases Smaller conc gradient is required for significant uptake of molecules Rate of facilitated diffusion inreases more rapidly and at lower conc. Diffusion rate reaches a plateau when carrier molecules become saturated (carrier saturation effect) |
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How is ATP different that the diffusion processes? |
Energy-dependent process ATP or proton motive force used Moves molecules against concentration gradient Concentrates molecules inside cell |
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How is active transport similar to facilitated diffuction? |
Involves carrier proteins (permeases) Carrier saturation effect is observed at high solute conc. |
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Where does Active transport by ABC transporters get its energy? |
ATP hydrolysis to directly transport molecules across the membrane |
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What does ABC stand for? |
ATP binding cassette transporters |
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What could Active transport transport? |
A variety of sugars, amino acids, inorganic compounds |
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What is a special case of molecule uptake and why? |
Ferric iron is very insoluble so uptake is difficult
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Microorganisms use _________________ to aid uptake of ferric iron. |
siderophores |
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Describe the mechanism of ferric iron uptake |
Siderophore complexes with ferric iron. The complex is then transported into cell by an ABC transporter |
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Describe the mechanism of ATP transport |
Two hydrophobic membrane spanning domains, associated on their cytoplasmic surfaces with two ATP binding domains Special substrate binding proteins are used to bind the solute Solute imported to the cell, the process is coupled to ATP hydrolysis for energy production |
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Define secondary active transport |
Transport couple to the movement of ions H or Na across the membrane |
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Secondary active transport by: |
Symport and Antiport |
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Describe symport |
Proton translocation across the membrane is an important way of energy generation Specific permiases could couple proton translocation to solute translocation across the membrane |
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Describe antiport |
Indirect utilization of energy generated during proton translocation Energy generated during proton gradient drive sodium ion expulsion Sodium couple to a permease Delivery of solute to the inside of the cell |
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How are different media classified? |
Chemical constituents from which they re made Physical nature Function |
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List the two types of chemical comp medias |
Defined or complex |
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List the four functional type media |
Supportive Enriched Selective Differential |
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Define Defined or synthetic media |
All components and their conc. are known |
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Define complex media |
Contiain some ingredients of unknown composition and/or concentration |
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Protein hydrolysates prepared by partial digestion of various protein sources . What is this defining? |
Peptones |
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What extracts are usually used in media? |
Aqueous extracts, usually beef or yeast |
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Define supportive or general purpose media |
Support the growth of many microorganisms Ex: Tryptic soy agar |
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Define enriched media |
General purpose media supplemented by blood or other special nutrients Ex: Blood agar |
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Define Selective media |
Favor the growth of some microorganisms and inhibit growth of others Ex: MacConkey agar |
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Define differential media |
Distinguish between diff groups of microorganisms based on their biological characteristics Ex: Blood, macconkey |
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Population of cells arising from a single cell. What is this defining? |
Pure culture |
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List techniques for isolating pure cultures
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Spread plate, streak plate, pour plate |
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Each cell can reproduce to form a separate ___________ (visible growth or cluster of microorgansims). |
colony |
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Describe the how and why spread plate and streak plates performed |
Involve spreading a mixture of cells on an agar surface so that individual cells are well separated from eachother |
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Describe the pour plate technique |
Sample is diluted several times Diluted samples are mixed with liquid agar Mixture of cells and agar are poured into sterile culture dishes |
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Where is colony growth most rapid? Why? |
At edge of colony; oxygen and nutrients are more available at edge |
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Where is colony growth slowest? |
At center of colony |
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In nature, many microorganisms form ______________ on surfaces. |
biofilms |
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How do microorganisms reproduce? |
By budding or binary fission |
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Increase in cellular constituents that may result in : |
Increase in cell # Increase in cell size |
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Microbiologists usually study population ______ rather than growth of individual cells. |
growth |
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Define cell cycle |
Sequence of events from formation of new cell through the next cell division - most bacteria divide by binary fission |
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What two pathways function during cell cycle? |
DNA replication and partition Cytokinesis |
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Most bacterial chromosomes are circular. TRUE OR FASLE |
TRUE |
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What is the single origin or replication? |
The site at which replication begins |
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What is the name for site at which replication is terminated, located at opposite of the origin? |
Terminus |
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Define replisome |
Group of proteins needed for DNA synthesis |
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Roles of MreB |
Determination of cell shape and thought to play a role in a chromosome partitioning to daughter cells |
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Define chromosome partitioning |
Replisome pushes, or leads to condensation of, daughter chromosomes to opposite ends |
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Describe the mechanisms of ParA/ParB |
ParA polymerizes to form filaments ParB binds DNA at parS site near origin of replication; technically, ParB binds 2 copies of parS site since DNA has been replicated ParA interaction with 1 of the 2 ParB/parS complexes causes it to depolymerize, pulling one copy of the DNA away |
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Define septation |
Formation of cross walls between daughter cells |
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What is the Z ring composed of? |
Protein FtsZ |
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What is septation involved with? |
Cytokinesis |
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List the steps for cytokinesis |
Selection of site for septum formation Assembly of Z ring (composed of protein FtsZ) Assembly of cell wall sythesizing machinery Constriction of cell and septum formation |
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What does MinCDE do? |
Limits Z ring to cell center - MinC, MinD, MinE oscillate from one side of cell to other - High conc. of MinC at poles prevents formation of Z ring at those locations |
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Describe Protein FtsZ |
Tubululin homologue, found in most bacteria and archaea Polymerization forms Z ring filaments of meshwork |
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Anchoring proteins link _________ to the plasma membrane. |
Z ring |
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What is cell growth and determination of cell shape determined by? |
Peptidoglycan synthesis in bacteria |
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What do penicillin binding proteins do? |
Link peptidoglycan strands and catalyze controlled degradation for new growth |
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What do autolysins? |
PBP enzymes that degrade peptidoglycan at site where new units are added |
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How does DNA replicate before cytokinesis is finished? |
The second, third, and fourth rounds of replication can begin before first round of replication is completed and progeny cells are "born" with two or more replication forks, replication already in progress |
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When is the growth curve observed? |
When microorganisms are cultivated in batch culture; culture incubated in a closed vessel with a single batch of medium |
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How is the growth curve plotted? |
Logarithm of cell number vs. time Usually has 5 distinct phases |
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List the 5 stages of the growth curve |
Lag, log, stationary, death, and long term stationary |
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What is happening during the lag phase? |
Cell synthesizing new components to replenish spent materials and to adapt to new medium or other conditions Varies in length |
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Log phase? |
(Exponential phase) Rate of growth is constant Population is most uniform in terms of chemical and physical properties during this phase |
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What does an abundance of nutrients do to the cell during the log phase? |
allows transport mechanisms to be saturate, so growth increase is minimul for adding in even more nutrients |
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Stationary phase? |
Total number of viable cells rains constant |
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List reasons for stationary phase occurring? |
May occur because metabolically active cells stop reproducing
May occur because repro rate is balances by death rate |
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List possible reasons for entry into stationary phase |
Nutrient limitation Limited oxygen availability Toxic waste accumulation Critical population density reached |
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List starvation responses from the cell |
Morphological changes like endospore formation Decrease in size, protoplast shrinkage, nucleoid condensation Productive of starvation proteins Long term survival Increased virulence |
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Death phase? |
Decrease in number of cells |
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Long term stationary phase? |
Cells are viable but not culturable (alive but dormant) Programmed cell death: fraction of the population genetically programmed to die (commit suicide) |
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What is the generation (doubling) time? |
Time required for the population to double in size |
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Name two ways you can measure changes in number of cells in a population |
Direct cell counts Viable cell counts |
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List different ways to direct cell count |
Counting chambers On membrane filters Flow Cytometry |
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List different ways to viable cell count |
Plating methods Membrane filtration methods |
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How can you measure microbial growth? |
Can measure changes in number of cells in a population Can measure changes in mass of population |
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How can you measure changes in mass population of microbial growth? |
Dry weight Quantity of a particular cell constituent Turbidimetric measures |
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Counting chambers are useful for counting both eukaryotes and prokaryotes. TRUE OR FALSE |
TRUE |
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Describe counting chambers |
Easy, inexpensive and quick Useful for counting both eukaryotes and prokaryotes Cannot distinguish living from dead cells |
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Describe counts on membrane filters |
Cells filtered through special membrane that provides dark background for observing cells Cells are stained with fluorescent dyes Useful for counting bacteria With certain dyes, can distinguish living from dead cells |
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Describe flow cytometry |
Microbial suspension forced through small orifice with a laser light beam Movement of microbe through orifice impacts electric current that flows through orifice Instances of disruption of current are counted Specific antibodies cn be used to determine size and internal complexity |
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After doing spread and pour plating, how are the results expressed? |
Colony forming units (CFUs) |
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Describe plating methods |
Simple and sensitive Widely used for viable counts of microorganisms in food, water, nd soil Inaccurate results obtained if cells clump together Only detects cells that can grow on the growth media used |
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Describe spread and pour plate techniques |
Diluted sample of bacteria is spread over solid agar surface or mixed with agar and poured into petri dish After incubation the number of organisms are determined by counting the number of colonies multiplied by the dilution factor Results expressed as CFUs |
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Describe dry weight
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Time consuming and not very sensitive |
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When is measuring the quantity of a particular cell constituent useful? |
If amount of substance in each cell is constant |
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Describe how turbidometric measures (light scattering) is |
Quick, easy and sensitive |
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More absorbance = ___________ transmition |
less |
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More cell --> more light scattered --> ____ light detected |
more |
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What is the name of organisms that grow under harsh conditions that would kill mot other organisms?
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Extremophiles |
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What two different microorganisms involve salty environmental conditions? |
Halotolerant and Halophilic |
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Define halotolerant |
Grows at low salt concentrations and can tolerate high salt concentrations |
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Define halophilic |
Grows only at high salt concentrations |
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How do halophilic microorganisms adapt to differences in osmotic pressure between the cytoplasm and the surrounding high salt environment? |
Absolute requirement of solutes (salt) Accumulates K in the cytoplasm Enzymes, ribosomes and transport proteins require high K for stability and activity H |
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How do halotolerant microorganisms adapt to differences in osmotic pressure between the cytoplasm and the surrounding high salt environment? |
Grow over wide ranges of water activity Many use compatible solutes to increase their internal osmotic concentration |
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Halophiles grow optimially at _______ M. |
>0.2 M |
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Extreme halophiles require _________. |
>2 M |
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List the different microorganisms based on pH |
Acidophiles Neutrophiles Alkalophiles |
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Define acidophiles |
Growth optimum between pH 0 and pH 5.5 |
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Define neutrophiles |
Growth optimum between pH 5.5 and pH 7 |
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Define alkalophiles |
Growth optimum between pH 8.5 and pH 11.5 |
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Most acidophiles and alkalophiles maintain an internal pH near ______________. |
neutrality |
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How is the internal pH of acidophiles and alkalophiles maintained at neutral? |
The plasma membrane is impermeable to protons Symport, antiport systems can be used to maintain pH closerr to neutrality |
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What do acid shock proteins do? |
Proteins that provide protection |
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How would microorganisms change their pH surroundings? |
By producing acidic or basic waste products |
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Organisms exhibit distinct cardinal growth temperatures: |
Minimal Maximal Optimal |
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How is the protein structure of thermophiles adapted to high temps? |
More H bonds More proline Chaperones |
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How has the membrane of thermophiles adapted to high temps? |
More saturated, more branched and higher molecular weight lipids, lipid monolayer Ether linkages (archaeal membranes) |
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List the different microorganisms that live in different temps from lowest temp to highest temp |
Psychrophiles |
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Define obligate aerobe |
Need oxygenDe |
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Define facultative anaerobe |
Prefer oxygen |
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Define aerotolerant anaerobe |
Ignore oxygen |
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Define strict anaerobe |
Oxygen is toxicDe |
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Define Microaerophilic |
<2-10% oxygen |
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Aerobes produce two protective enzymes: |
Superoxide dismutase (SOD) Catalase |
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Oxygen is easily reduced to toxic products |
Superoxide radical Hydrogen peroxide Hydroxyl radical |
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Name the two different microorganisms based on pressure |
Barotolerant and Barophilic |
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What organism is adversely affected by increased pressure, but not as severely as nontolerant organisms |
Barotolerant |
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Define barophilic |
Require or grow more rapidly in the presence of increased pressure |
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Describe the three ways there can be radiation damage |
Ionizing radiation Ultraviolet radiation Visible light |
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Visible light at high intensities generates _________________________. |
Singlet oxygen |
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What do carotenoid pigments do? |
Protect many light-exposed microorganisms from photooxidation |
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What does ionizing radiation do? |
Disrupts chemical structure of many molecules including DNA |
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What radiation damage causes formation of thymine dimers in DNA?
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Ultraviolet radiation |
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Define chemotaxis |
Movement towards a chemical attractant or away from a chemical repellent How |
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How are the concentrations of chemical attractants and chemical repellents detected? |
By chemoreceptors on surfaces of cells |
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How does movement of microbe change in presence of chemotaxis? |
Less tumbling and more runs in longer directions |
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What does FtsZ do? |
Forms ring during septum formation of cell division |
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What does MreB do? |
Maintains shape by positioning peptidoglycan synthesis machinery |
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What does CreS do? |
Maintains curve shape |
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Define storage inclusions, give examples |
Granules of organic and inorganic material that are stockpiled by the cell for future use Glycogen storage, sulfur granules |
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Define nonstorage inclusions, give examples |
Granules of enzymes, structures or specific chemicals that are required for proper cell function Carboxysomes, gas vacuoles, magnetosomes |
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What are carboxysomes? |
CO2 fixing bacteria |
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What is rubisco? |
Enzyme involved with CO2 fixation |
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The 70S ribosome consists of two units: |
50S and 30S |
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The 50S ribosomal unit:
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LSU: 23S rRNA + 5S rRNA + ribosomal proteins |
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The 30S ribosomal unit: |
SSU: 16S rRNA+ ribosomal proteins
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Genes on plasmids are not essential to the host but may confer selective advantage. TRUE OR FALSE |
TRUE |
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Loss of plasmid is called what? |
Curing |
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List cell wall functions (4) |
Maintains shape Helps protect cell from osmotic lysis Helps protect from toxic materials May contribute to pathogenicity |
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Difference between gram positive and gram negative cell wall |
G+ has a large peptidoglycan layer G- has a relatively smaller peptidoglycan layer which an outer membrane and a periplasmic space |
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Describe the peptidoglycan subunit
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Repeating units of NAG-NAM with a peptide chain |
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Chains of linked peptidoglycan subunits could be _______________ by peptides. |
cross-linked |
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Peptide interbridge is mostly in gram negative bacteria. TRUE OR FALSE |
FALSE; peptide interbridge in gram positive bacteria |
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Teichoic acid in cell walls of Gram positive or gram negative? |
Gram positive |
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Periplasmic space takes up 20-40% of cell volume in gram positives. TRUE OR FALSE |
FALSE; it does in gram negatives |
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What does gram negatives outer membrane consist of?
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Lipid bilyer, lipoproteins, porins and lipopolysaccharides (LPS) |
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How does the outer membrane connect to the cell? |
Brauns protein, adhesion sites |
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List the three parts of LPS |
Lipid A Core polysaccharide O-antigen |
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Out of the three parts of LPS, which can act as a toxin? |
Lipid A |
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List the importances of LPS |
Helps stabilize outer membrane (Lipid A) Can act as a toxin (Lipid A) Contributes to negative charge on cell surface (core polysaccharide) Protection from host defenses (O antigen) |
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Why is the outer membrane more permeable that the plasma membrane? |
Porin proteins and transporter proteins; porin proteins form channels through which small molecules can pass |
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What does gram staining do to the cell wall of gram positive organisms? |
Thought to involve the shrinkage of the pores of the peptidoglycan layer - constriction prevents the loss crystal violet during decolorization step |
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Define osmotic lysis |
Movement of water into cell causes swelling and lysis due to osmotic pressure; can occur when cells are in hypotonic solutions |
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What does penicillin do in the cell wall? |
Inhibit peptidoglycan synthesis |
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What does a lysozyme do relative to the cell wall? |
Breaks the bond between NAG and NAM |
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Define protoplast |
Cell completely lacking cell wall (eg Gram+ that have been treated with penicillin) |
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What are the two parts of glycocalyx? |
Capsules: not easily removed Slime layers: easily removed |
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S layers are common among archaea where they could be the only structure outside the plasma membrane. TRUE OR FALSE |
TRUE |
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Archaeal cell walls lack? |
peptidoglycan |
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Define monotrichous |
One flagellum |
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Define polar flagellum |
Flagella at end of cell |
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Define amphitrichous |
One flagellum at each end of cel |
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Define lophotrichous
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Cluster of flagella at one or both ends of cell |
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Define peritrichous |
Flagella spread over entire surface of cell |
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Describe flagella structure |
Flagellar filament: extends from cell surface to tip Basal body: embedded in the cell membrane Flagellar hook: Links the filament to the basal body, acts as a flexible coupling |
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What is the largest most visible part of the flagella? |
The filament |
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What is the filament composed of? |
Protein flagellin, capping protein |
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Which flagella structure has a series of rings that drives flagellar motor? |
Basal body |
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Difference between G+ and G- flagellar basal body |
G- has four rings connected to a central rod G+ has two basal body rings |
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What protein is used for synthesis of flagella? |
Flagellin |
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Growth is from tip, not base, for bacterial and archaeal flagella. TRUE OR FALSE |
FALSE; growth is from tip for bacteria but from base for archaea
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What are the four different types of motility ? |
Flagellar movement Spirochete Twitching Gliding |
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Describe flagellar movement
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Flagellum rotates like a propellar on a boat, rings rotate, convey motion to the filament Counterclockwise causes forward motion (run) and clockwise rotation disrupts causing a tumble |
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What is the electrical motor of flagellar movement powered by? |
Ion gradient |
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Spirochete motility |
Multiple flagella wind around the cell and although it rotates similarly to flagellar movement, it has a creeping/ crawling motility |
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Twitching motility |
Involves pili at ends of cell on moist surfaces; short intermittent jerky motions because of extension and retraction of pili |
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Gliding motility |
May involve pili or slime; movement glides across surface - the how is not well known |
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Two types of myxococcus xanthus movement |
Social: twitching motility but with groups Adventurous: movement by gliding by slime or by adhesion complex |
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Define sporogenesis |
Endospore formation which happens when growth stops due to lack of nutrients |
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Define germination |
Transformation of endospore into vegetative cell |
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What are the four different endospore locations? |
Subterminal, terminal, central, or swollen sporangium |
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What makes an endospore so resistent? |
Exosprangium: non specific protection from chemicals Spore coat: thick and impermeable Dipicolinic acid: thought to help with heat resistance Calcium: increases resistance to wet heat SASPs: help protect from heat, radiation and chemicals |
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Describe the two component signal transduction system |
Sensor kinase senses a specific environmental stimuli and autophosphorylates a specific histidine residue. This phosphorylation of sensor kinase relays the signal to a response regulation, causing its activation through phosphorylation. Activation of response regulator mediates the required response |
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What are the two major pathways for protein secretion? |
Sec and TAT |
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All protein secretion systems require energy. TRUE OR FALSE |
TRUE |
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Describe the Sec dependent pathway |
Secreted proteins synthesized as preproteins having an amino-terminal signal recognition peptide (SRP) Chaperone proteins keep preproteins unfolded |
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How does TAT differ from Sec? |
TAT translocates folded proteins while Sex translocates unfolded proteins |
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7 secretion pathways have been found for gram negative bacteria. TRUE OR FALSE |
FALSE; only 5 |
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Type 2 and 5 pathways for G- |
Transport proteins across the outer membrane that were translocated across the plasma membrane by Sec Type 2 could also transport proteins that were translocated by TAT |
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Type 1 and 3 pathways for G- |
Sec independent |
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Type 4 of G- |
Functions independently of Sec, could be involved with DNA transfer (conjugation) |
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Which protein secretion pathway in G- involves a chaperone protein? |
Type 3 |
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Which pathway for protein secretion in G- involves an ABC? |
Type 1 |
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Microelements are required in large amounts. TRUE OR FALSE |
FALSE; macroelements are required in large amounts, microelements in trace amount |
