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Types of passive transport
- Simple Diffusion
- Osmosis
- Facilitated diffusion
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Purpose of Active transport
- Accumulate materials against the concetration gradint
- (Uses energy)
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Active transport system components
- Membrane spanning protein/component
- Periplasmic binding protein/component
- Other proteins
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Three classes of active transport systems
- Simple transport (Uses PMF)
- Group translocation (Chemical modification of transported compound)
- ABC Transporters (ATP Use)
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Phosphotranferase use
- Importing glucose
- Glucose is phosphorylated by PEP
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Exporter proteins are called...
Translocases
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Sec System
- Export system (proteins)
- Found in bacteria
- Highly conserved
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Roles of the bacterial cell wall
- Cell shape
- Protect against osmotic shock
- Flagella anchorage
- General protection
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Gram positive cells have a cell wall. (T/F)
True - Thicker peptidoglycan layer holds onto crystal violet
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Polysaccharide components of bacterial peptidoglycan
- N-acetylmuramic acid (NAM)
- N-acetylglucosamine (NAG)
- -(-NAM-NAG-)-
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Peptide components of peptidoglycan
- L-Ala, d-Glu, L-Lys?, D-Ala
- Tetrapeptides linked to NAM and NAG
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Alternative to L-Lys in gram negative peptidoglycan
Diaminopimelic acid (DAP)
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Autolysins
Used by bacteria to maintain it's cell wall
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Lysozyme activity
Cleaves β,1-4 linkages between NAG and NAM
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Spheroplast and Protoplast
- Sphereoplast - Partial cell wall removal
- Protoplast - Complete cell wall removal
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Thickness of a g++ cell wall
- 25 Layers of up to 90%peptidoglycan
- 20nm-80nm
- Techoic acids bind covalently
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Alternatives to techoic acids in gram negative organisms
Lipoproteins
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Main structural component of the outer-outer membrane in G--
- Lipopolysacchrides
- Various uses - Permeability, protection from immune reponse
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Porins
Found on the outer-outer membrane
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Width and function of the periplasmic space
- 15nm
- Various reactions; redox, hydrolysis
- Transport and secretion
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Components of archeal cell walls
- Pseudopeptidoglycan
- Proteins or glycoproteins (S-layers)
- Polysaccharides
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Pseudopeptidoglycan
- NAG and NAM
- Linked by β-1,3 linkages
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Layers outside of the cell wall
- Capsule - Rigid matrix excludes dyes
- Slime Layer - Easily deformed, loose
- Extracellular Polymeric substances
- S-Layer
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Glycolax
Capsule and slime layer, used in biofilms
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