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Structure and Function of Bacteria
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31
Microbiology
Undergraduate 3
01/31/2013

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Term
Types of Microorganisms
Definition
1. Bacteria
2. fungi
3. parasites
4. viruses
Term
Prokaryotic
Definition
-early nucleas
-bacteria/algi
Term
Eukaryotic
Definition
-membrane bound
-true nucleas
-animals/fungi
Term
Prokaryotic cell
Definition
appendages
cell envelope
cytoplasm
endospores
Term
Appendages
Definition
flagella
fimbriae or common pili
sex pilus
Term
cell envelope
Definition
glycocalyx (slime layers, capsule)
cell wall
cell mambrane
Term
cytoplasm
Definition
cell pool
nucleoid: chromosome
plasmids
ribosomes
inclusion bodies/granules
Term
Flagella
Definition
not all bacteria have
long hair-like appendages composed of multiple units of flagellin
-vary in # and arrangment
dircted mvmnt influenced by - & + chemotaxis
Term
fimbriae or common pili
Definition
short hairs on exterior of cell
thinner than flagella
composed of multiple units of pilin
adhesin / aggresin / indavin
*main function: attchmt
fimbriae: 100s of hairs
pili: about 20 hairs
Term
virulent factor
Definition
can attach, has pili
increases pathogenesis ( ability to cause infection)
Term
sex pilus
Definition
elongate, rigid, hollow tubular structure through which dna may be transferred (bacterial conjugation)
Term
cell envelope (glycocalyx)
Definition
sticky gelatinous layer around some but not all bacteria
composed of a polysaccharide/protein mix-variable thickness
function: protection (of extreme environmental conditions, loss of water and nutrients) and attachment
Term
Slime Layer
Definition
loose soluble shield non-uniform in density or thickness that protects cell from dehydration and nutrient loss
-aid in bacterial attchmnt
-composition: polysaccharide protein mix
Term
capsule
Definition
thick gelatinous polymer firmly attached to cell wall that contributes to bacterial virulence by potecting bacteria from phagocytosis and destruction by certain white blood cells
Term
cell wall
Definition
gives bacterium its shape
protects cell from osmotic lysis by confining the cytoplasmic membrane
thickness depends on gram - or gram +
-primary component: heteropolymer peptidogylcan
Term
peptidogylcan
Definition
long polysaccharide chains of 2 repeating disaccharides (glycan chains)
1. NAG & 2. NAM
-glycan chains are cross-linked by short tetrapeptide between M subunits
Term
Gram + cell wall
Definition
blue/purple
primarily composed of peptidoglycan (40 multiple layers) (90% of cell wall)
remaining 1-%: 1. teichoic acid & 2. lipoteichoic acid
Term
Function of teichoic acid & lipoteichoic acid
Definition
1. assist in the transport of ions
2. reinforce cross linking btwn glycan chains
3. increase rigidity of cell wall

-tetrapeptides (maybe referred to as interbridging) also increase rigidty of cell wall
Term
Gram - cell wall
Definition
-3 layered cell wall
-single layer of peptidoglycan thus weaker cell wall than gram +
Term
Gram - cell wall
outer membrane
Definition
-largest part of cell wall
-external to peptidoglycan layer
-semipermeable
-phospholipid bilayer
-contains:
a. lipopolysaccharides (anchor)
b. lipoproteins (hold outer membrane to peptidoglycan layer)
c. porin proteins-protein channels ( nonspecific protein channels so materials can enter in periplasmic space)
Term
Gram - cell wall
periplasmic space
Definition
-main function
-narrow gap btwn the inner and outer membrane
-contains degradative or hydrolytic enzymes-phosphates, nucleases, proteases and lipases
-contains peptidoglycan
-porin proteins allow material to enter periplasmic space
Term
Gram - cell wall
peptidoglycan
Definition
one layer thick
Term
eukaryotic cell membrane
Definition
-bacterial analog for membrane bound organelles
-thin flexible structure inside cell wall, molded around cytoplasm
-phospholipid bilayer containing specialized proteins(peripheral and integral)
-phospholipid molecule consists of polar head ( hydrophilic) and non polar tains (2 long chain fatty acids-hydrophobic)
-semi-permeable
-site of metabolic activities atribute to eukaryotes:
1. respiration/photosynthesis
2. transport systems
3. synthesis of cell wall components
4. synthesis of lipids
5. secretion of exoenzymes to periplasmic space
6. secretion of toxins (virulent factors)
-discharge of waste (co2, h2o, etc)
Term
peripheral protein
Definition
exterior surface
Term
integral protein
Definition
hydrophillic & hydrophobictendencines in the phospholipid layer
Term
cytoplasm
Definition
70-80% made of h2o
-internal matrix of cell contained inside the cell mambrane
-dense gelatinous solution with primary component of h20
-within h2o is cell pool (complex mix of nutrients which is the building block for cell synthesis/metabolism or sources of energy/catabolism)
Term
necleoid (chromatin)
Definition
-single circle of double stranded dna with specialized proteins
-irregularly shapes/ minimal material needed for bacterial survival
-contains genetic info for cell structure and function
-not enclosed by a membrane
-aka nuclear region
Term
plasmids
Definition
extra piece of dna
-found in most bacteria but not all
-antibiotic resistance
-production of toxins
-production of enzymes
Term
ribosomes
Definition
free in cytoplasm or attached to inner membrane
-granules of rna and proteins that function as sites for protein synthesis
Term
inclusion bodies / storage granules
Definition
-amophous particles floating in the cytoplam and composed of reserve nutrients stored when in abundance
-may contain polysaccharides (glycogen or starch), lipids (polymer of b-hydroxy-butyric acid; phb) or poly-phosphate (inorganic phosphate)
Term
endospores
Definition
mechanism of survival
-only certain bacteria can form a spore (advantagis for bacteria)
-not growth, its a means for survival
-1 bacteria can only form 1 spore and visa versa
-synthesized in the cytoplasm of certain gram + bacteria
-no metabloc activity/growth
-resistant to environmental stress
-when proper nutrients are present, endospore becomes activated and will germinate into a normal bacterial cell
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