Chapter 3 Flashcards
Prokaryote Size. Shape, and Arrangement
Shape: -cocci and rods -other Arrangement: -determined by plane of division - " by separation or not Size: -varies
Cocci (coccus) Shape
Spheres
- diplococci
- streptococci -chains
- staphylococcii - grape like clusters
- tetrads - 4 cocci in a square
- sarcinae - cubic formation of 8 cocci
Other Shapes: Bacilli, Virbrios, Spirilla
Bacilli (bacillus) - rods
-coccobacilli - very short rods
Vibrios - comma shaped rods
Spirilla - rigid helices
Other Shapes: Spirochetes, Mycelium, Pleomorphic
Spirochetes - flexible helices
Mycelium - long multinucleate filaments
Pleomorphic - variable in shape
Size of Prokaryotes
Smallest = 0.3 nm (mycoplasma)
avg rod - 1.1-1.5x 2-6m
v large -600-80m (epulopiscium)
Size-Shape relationship
nutrient uptake
S to V ratio S/V
Small size may be protective mechanism from predation
Bacterial Cell Organization-Common Features
Cell envelope
(plasma, cell wall, capsule/slime layer)
Cytoplasm
External Structures
Bacterial Plasma Membrane
- req
- some w/ internal membrane
Function of Plasma Membrane
Encompass cytoplasm Selectively permeable Interacts w/ external environment - receptors -> chemicals in surroundings -transport systems -metabolic processes
Fluid Mosaic Model of Membrane Structure
lipid bilayers with floating proteins
- amphipathic
- > polar ends(hydrophillic) + non polar tails (hydrophobic)
- membrane proteins
Peripheral Proteins
loosely connected to membrane
easily removed
Integral Proteins
within membrane
carry out impt fxns
maybe as microdomains
Bacterial Lipids
saturation levels = enviro conditions (eg. t)
- bacterial membranes lack sterols, contain sterol like molecules, hopanoids
- stabilize membrane
- in petroleum
Uptake of nutrients (macro)
- C,O,H,N,P,S,
- > organic molecules (proteins, lipids, carbs, nucleic)
- K, Ca, Mg, Fe
- > cations (enzymes, biosynthesis)
- req in large amounts
Uptake of nutrients (micro)
- Mn, Zn, Co, Mo, Ni, Cu
- > trace amounts
- > in water, or media comp.
- > ubiquitous
- > enzymes/cofactors
Uptake of nutrients - Growth Factors
Org, compounds
- essential cell components,
- supplied by enviro
Classes of growth factors
AA -protein syn Purines + Pyrimidines -NA+synthesis Vitamins -enzyme cofactors
What transport mechanisms do microorganisms use?
Facilitated diffusion,
Active Transport
Group Translocation
Passive Diffusion
Higher > lower [] between interior and exterior,
-H20, 02, C02
Facilitated Diffusion
not energy dependent direction from high to low size of [gradient] - rate of uptake -channels/ carrier proteins involved (permeases) -small [] gradient MORE IN EUK, THEN BAC AND ACH
Active Transport
Req E, (ATP/proton motive force used)
against gradient (low-high)
carrier proteins
ABC Transporters
Primary Active Transporters use ATP
-> transporters
(ALL)
2 binding domains
Secondary Active Transport
Major Faciliator Superfamily
ion gradient -> cotransport substances
-> protons,
-> symport - two substances in SAME direction
-> antiport - two substances in OPPOSITE direction
Group Translocation
E dep transport- chemically modifies molecule brought into cell
Phosphoenolpyruvate: sugar phosphotransferase system (PTS)
Iron Uptake
Ferric - insoluble
Siderophores - aid uptake
-> complex with ferric
–> then transported into cell
Peptidoglycan Structure
Long strands
2 sugars: NAG+lactic acid attached by ether linkage, NAM
D+L AA
-crosslinkage
Gram-Negative Cell Walls
More complex than +ve
no teichoic acids
enzymes in intermembrane space
Lipopolysaccharide (LPS)
- o side chain
- core polysaccharide
- lipid A
- ve charge on cell surface
- stabilize other mem structure
- attatchement to surfaces and biofilm
- permeability barrier
- protection from host defences
- endotoxin
