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51 Cards in this Set
- Front
- Back
What are the two differences between gram negative and gram positive bacteria?
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Thinner peptidoglycan than gram positive.
Surrounded by an outer membrane. |
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What is the outer leaflet of the outer membrane made of?
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Lipopolysaccharide
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What three components is lipopolysaccharide composed of? In to out.
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Lipid A
Core Polysaccharide O-Polysaccharide |
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What is Lipid A?
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4 to 6 3-hydroxy-fatty acids attached to dimer of glucosamine phosphate.
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What is the Core Polysaccharide?
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A fairly conserved linker. 8, 7 and 6-carbon sugars.
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What is the O-Polysaccharide? Is it strain specific?
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4 to 5 sugars repeated 10 to 20 times. Highly strain specific (somatic antigen).
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What typical disease-related symptom does LPS cause? What component causes this?
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Causes fever, caused by Lipid A.
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What holds the outer membrane to the thin peptidoglycan layer (and thus to the cell)?
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Lipoproteins
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What are the layers of of the cell membrane/wall for gram positive bacteria? In to out.
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Plasma membrane
Peptidoglycan Teichoic Acid |
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What is the function of teichoic acid?
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Improve the rigidity of the cell wall by attracting cations such as magnesium and sodium.
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What are the layers of of the cell membrane/wall for gram negative bacteria? In to out.
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Plasma Membrane
Peptidoglycan (Lipoprotein connecting) Outer Membrane Lipopolysaccharide |
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What is the peptidoglycan arrangement in gram negative rods? What is the orientation of the peptide cross links?
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Polysaccharide chains wrapped around circumference of the cell. Peptide cross links are parallel to cell axis.
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What is the peptidoglycan arrangement in gram positive rods?
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Wound in cables that wrap around the cell.
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What are the consequences of the lipopolysaccharide layer?
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Hydrophilic O Polysaccharide repels hydrophobic molecules that would otherwise penetrate the cell membrane.
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How can small hydrophilic molecules enter the cell?
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Can freely enter through porins.
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Enterobacteriaceae have what reaction to oxygen and what shape are they?
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Facultatively anaerobic
Gram negative rods |
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Enterobacteriaceae have what type of flagella, what type of reaction to the oxidase test? Where are they found?
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Petritrichous flagella
Negative oxidase test Found in soil and intestines |
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What are the two ways Enterobacteriaceae can create energy?
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Respire with oxygen, nitrate or fumarate
Ferment sugars to butanediol or mixed acids |
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What is a famous example of a gram negative rod in the Enterobacteriaceae family?
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E. Coli
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Genus Pseudomonas has what reaction to oxygen and what cell shape?
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Reaction to Oxygen: Aerobic
Shape: Gram negative rods |
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Genus Pseudomonas have what type of flagellum, what is their result in the oxidase test and where are they common?
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Polar flagellum
Oxidase positive Common in soil and water |
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What are some functions of pseudomonas?
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Plant pathogens
Plant growth promoters Degraders of toxic chemicals |
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Bacteroids have what reaction to oxygen? How do they create energy.
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Die. (Anaerobic)
Fermentative |
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What is the major permeability barrier?
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Cytoplasmic membrane
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Is peptidoglycan a barrier to small molecules?
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No
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What kind of resistance does the outer membrane present?
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Repels hydrophobic molecules but allows small hydrophilic molecules to enter via porins.
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What is passive transport?
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Movement of molecules down their concentration gradient, so no energy is needed to transport the molecule.
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What is active transport?
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Movement of molecules against their concentration gradient, so ATP or a proton gradient is needed to transport the molecule.
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What are the two types of passive transport?
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Simple diffusion
Facilitated diffusion |
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What is simple diffusion? What molecules can do this?
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Molecule passes through membrane
Small hydrophobic molecules do this. |
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What is facilitated diffusion? What molecules can do this?
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Hydrophobic channels require channels or carriers to be transported across the membrane.
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What is an example of facilitated diffusion channel protein in E. Coli?
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GlpF glycerol transporter
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Does facilitated diffusion heavy rely on high external concentration?
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Yes.
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What is the first example in the lectures of active transport?
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Proton Symport
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How is proton symport carried out?
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Substrate brought into cell by entering with a proton.
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How is proton symport driven?
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Transmembrane proton gradient.
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Do both the proton and substrate enter in the same direction with symport?
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Yes.
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What is an example of symport in E. Coli?
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LacY (Lactose Permease)
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What is the first example in the lectures of active transport?
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ATP Hydrolysis
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How is ATP hydrolysis carried out? What drives transport.
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With ABC transporters (ATP-Binding Cassettes)
Hydrolysis of ATP. |
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What is the ABC Transporter often associated with in gram negative bacteria?
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Periplasmic substrate-binding protein.
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What is an example of an ABC Transporter associating with a periplasmic substrate-binding protein in gram negative bacteria?
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MalFGK, or the maltose transporter & periplasmic maltose-binding protein MalE.
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What is the third example in the lectures of active transport?
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Group Translocation
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What happens to the substrate during Group Translocation?
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The substrate is modified, typically phosphorylated.
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What is an example of Group Translocation in bacteria?
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The Phosphotransferase System
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What is the imported glucose changed into in the phosphotransferase system?
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Glucose-6-Phosphate
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Where does the phosphate come from? How
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Derived from PEP (phosphoenolpyruvate).
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How does transport happen across the outer later (excluding porins and hydrophilic molecules)?
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Some substances actively transported using energy derived from cytoplasmic membrane.
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How is energy transduced from the cytoplasmic membrane to the outer membrane?
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TonB transduces it, but in an unknown way.
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What are two of transport across the outer membrane?
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Iron-siderophore complexes and FepA transporter
Vitamin B12 complex, BtuB transporter |
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What is a Nosocomial infection?
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An infection originating in a hospital.
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