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The flashcards below were created by user
Scottygo
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Coccus (pl. cocci):
spherical or ovoid
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Cells with unusual shapes
 – Spirochetes, appendaged bacteria, and filamentous bacteria
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Size range for prokaryotes: ____ μm to > ___ μm indiameter
0.2->700
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Most cultured rod-shaped bacteria are between ____ and____μm wide and <__ μm long
- 0.5-4.0um wide
- <15 um long
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Two examples of large prokaryotes
- • Epulopiscium fishelsoni
- • Thiomargarita namibiensis
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Size range for eukaryotic cells: ___ to >___ μm indiameter
10 to >200 μm
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Advantages to being a small cell
- Small cells have more surface area relative to cell volume than large cells (i.e., higher S/V)
- – support greater nutrient exchange per unit cellvolume
- – tend to grow faster than larger cells
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Cytoplasmic membrane
- – Thin structure that surrounds the cell
- – 6–8 nm thick
- – Vital barrier that separates cytoplasm from environment
- – Highly selective permeable barrier; enablesconcentration of specific metabolites andexcretion of waste products
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Sterols
• Rigid, planar lipids found in eukaryotic membranes Strengthen and stabilize membranes
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What two ions help stabilize membrane by forming ionic bonds with negative charges on the phospholipids
Mg2+ and Ca2+
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Hopanoids
- • Structurally similar to sterols
- • Present in membranes of many Bacteria
- very hydrophobic planar structure
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Arcahaeal Membranes
-what kind of linkages in phosholipids?
- – Ether linkages in phospholipids of Archaea(H-H)
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Bacteria and Eukarya that have ___ linkages in phospholipids
- ester (B.E.ST)
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Archaeal lipids lack fatty acids, have____instead
- isoprenes
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in Archaeal Membranes the Major lipids are ____ _____ and _______
- glycerol diethers and tetraethers
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Do Archael membranes exist as monolayers, bilayers or a mixture?
they can exist as lipid monolayers, bilayers, or mixture
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Group translocation:
- A mechanism utilized by bacteria to transport a compound into their cell by first allowing the compound to bind with protein on the cell surface followed by altering its chemical structure during its passage across the membrane. driven by phosphoenolpyruvate
- -The Phosphotransferase System in E. coli
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Uniporters
- -transport in one direction across the membrane
- -ex:K+ in, power by electrical difference between out and in
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– Symporters
- function as co-transporters
- -Lactose is transported into E. coli by the simple transporter lac permease, a symporter (lactose and H+)
- -Activity of lac permease is driven by proton gradient
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Antiporters
- -transport a molecule across themembrane while simultaneously transporting another molecule in the opposite direction
- -ex:Na+ out H+ in
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The Phosphotransferase System in E. coli
- – Type of group translocation: substance transported is chemically modified during transport across the membrane
- – Best-studied system
- – Moves glucose, fructose, and mannose– Five proteins required
- – Energy derived from phosphoenolpyruvate
- -Phosphate group is attached to molecule being transported
 Hpr- heat stable protein- Enz1 provides energy from Phosphoenolpyruvate in form of phosphate
- Phosphate is transfered from component to component untill enz2c where it drives transport of and is bonded to the sugar
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periplasmic binding proteins
Binds to substrate in periplasm and then binds to mouth of a transporter to pass substrate through to cytoplasm
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• ABC (ATP-Binding Cassette) Systems
- – >200 different systems identified inprokaryotes
- – Often involved in uptake of organiccompounds (e.g., sugars, amino acids),inorganic nutrients (e.g., sulfate, phosphate),and trace metals
- – Typically display high substrate specificity
- – Contain periplasmic binding proteins
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NAG
- N-acetylglucosamine
- Glucose attached to acetyl group (C2)
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NAM
- N-acetylmuramic acid
- same as NAG apart from a chain branching from C3
- 1-lactic acid
- (4 aminos-Glycan tetrapeptide)
- 2-L-alanine
- 3-D-glutamic acid
- 4-diaminopimelic acid(G+) or L-Lysine(G-)
- 5-D-alanine
- (LAGDA-LDD or LAGLAGGGGG-LDLD)
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Peptidoglycan
- – Rigid layer that provides strength to cell wall
- – Polysaccharide composed of
- • N-acetylglucosamine (NAG) and N-acetylmuramic acid(NAM)
- • Amino acids
- • Lysine or diaminopimelic acid (DAP)
- • Cross-linked differently in gram-negative bacteria and gram-positive bacteria (Figure 3.17)
- - prominent in gram positive
- -lysozyme sensitive bond
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Teichoic acid
- bacterial polysaccharides of ribitol phosphate found on Gram positive bacteria
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• Gram-Positive Cell Walls
- – Can contain up to 90% peptidoglycan
- – Common to have teichoic acids(acidicsubstances) embedded in the cell wall
- • Lipoteichoic acids: teichoic acids covalentlybound to membrane lipids
- -NAM branch contains L-Lysene and extra 5 Glycene
- LAGLAGGGGG-LDLD
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Gram negative Bacteria
- • Total cell wall contains ~10% peptidoglycan(Figure 3.20a)
- • Most of cell wall composed of outer membrane (outer layer of outer membrane composed of lipopolysaccharides [LPS] )
- – LPS consists of core polysaccharide and O-polysaccharide
- – LPS replaces most of phospholipids in outerhalf of outer membrane
- – Endotoxin: the toxic component of LPS(what our body reacts to)
- LAGDA-LDD
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Lipopolysaccharide (endo toxin)
- -composed of Lipid A- 6 or 7 fatty acids attached to 2 glucosamine (toxic)
- -Core polysaccharide- 7 specific sugars
- -O-specific polysaccharide- antigen(sets off imune system) group of sugars repeated over and over
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Porins:
channels for movement of hydrophilic low molecular weight substances in outer membrane
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Periplasm:
– ~___ nm wide
– Contents have ____-like consistency
– Houses many ______
- space located between cytoplasmic and outer membranes
- – ~15 nm wide
- – Contents have gel-like consistency
- – Houses many proteins
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Energy conservation
- how bacteria create energy through a proton gradient (high concentration of + out; low in(- on inside) polar membrane)
- -proton flow into the cell (proton motive force) is harnessed for energy
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