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Ch 4
Ch. 4 Prokaryotes
55
Microbiology
Undergraduate 2
07/10/2010

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Term
characteristics of prokaryotes
Definition
-DNA not enclosed in a membrane
-DNA not associated with histones
-no membrane bound organelles
-cell wall of peptidoglycan
-divide by binary fission
-bacteria and archea
Term
3 basic shapes
Definition
cocci (spheres), bacilli (rods), spiral
Term
arrangements of cocci
Definition
-diplococci
-streptococci
-tetrad
-sarcinae
-staphylococci
Term
streptococci
Definition
chains
Term
tetrad
Definition
group of 4 cocci
Term
sarcinae
Definition
group of 8 cocci
Term
staphylococci
Definition
grapelike
Term
types of bacilli
Definition
-diplobacilli
-streptobacilli
-coccobacilli
Term
types of spiral
Definition
-vibrio
-spirillum
-spirochete
Term
vibrio
Definition
curved rods
Term
spirillum
Definition
helical shape (use flagella)
Term
spirochete
Definition
helical and flexible (axial filaments)
Term
3 other shapes
Definition
-star
-rectangle
-triangle
Term
star
Definition
stella
Term
rectangular
Definition
haloarcula
Term
triangular
Definition
angulomicrobium
Term
external structures to the cell wall
Definition
-glycocalyx
-flagella
-pili/fimbriae
Term
glycocalyx
Definition
-general term to describe substances that surround the cell
-viscous, sticky, gelatinous polymer of polysaccharides/polypeptides or both
-capsule (organized tight)
-slime layer(loose)
Term
functions of glycocalyx
Definition
-act as a barrier to toxic hydrophobic molecules (detergents)
-can enable adherence to other bacteria or host tissue (biofilms)
-major virulence factor due to its weak antigenic and antiphagocytic properties
Term
flagella and types
Definition
-composed of helically coiled proteins (flagellin)
-peritrichous
-monotrichous and polar
-lophotrichous and polar
-amphitrichous
Term
peritrichous
Definition
distributed over entire cell
Term
monotrichous and polar
Definition
single flagellum at one pole
Term
lophotrichous and polar
Definition
many flagella at one pole
Term
amphitrichous
Definition
flagella at both poles
Term
flagella movement
Definition
-driven by rotary engine composed of proteins located at flagellum's anchor point on the inner cell membrane (basal body)
-powered by proton motive force
Term
pili/fimbriae
Definition
-thin protein tubes originating from plasma membrane
-found in all gram negative bacteria
Term
pili
Definition
-shaft composed of pilin
-involved in motility
-bring bacteria together and allow transfer of DNA (conjugation)
Term
fimbriae
Definition
-can occur at poles or over entire surface
-promote attachment to other bacteria and host
-virulence factor
-ex. E. coli colonization
-N. gonorihoeae urinary infection
Term
the cell wall and functions
Definition
-contains semi rigid, tight knit, molecular complex of peptidoglycan(NAG,NAM,peptides)
-protects inside of cell from detrimental changes in the outside environment
-prevents cell from rupturing in hypotonic conditions
-maintains shape
-provides ligands(binds to receptors) for adherence
-essential structure for cell viability
Term
NAM and NAM
Definition
-linked in rows of 10-65 sugars
-attached to peptide chain of 4 amino acids (direct and cross linked)
Term
The gram stain
Definition
-named after Hans Christian Gram (1884)
-one of the most important techniques in microbio
-based on ability of bacteria cell wall to retain primary crystal violet dy during solvent treatment
Term
Gram stain steps
Definition
-apply crystal violet
-apply iodine (mordant)
-decolorize with alcohol
-apply safranin (counterstain)
Term
Gram + stain mechanism
Definition
-high peptidoglycan
-low lipid
-pores shrink from alcohol
-CVI complex retained
Term
Gram - stain mechanism
Definition
-low peptidoglycan
-high lipid
-dissolution of lipid membrane from alcohol
-CVI complex washes out
-cell takes up counterstain
Term
Gram + cell wall characteristics
Definition
-thick peptidoglycan (20-80nm)
-contains teichoic acids (wall and lipo)
-contains alcohol group (glycerol,ribitol) and phosphate group
-may be involved in regulating flow of cations
-important surface antigens involved in adherence
Term
Gram - cell wall characteristics
Definition
-thin peptidoglycan (7-8nm)
-no teichoic acids
-possesses outer membrane
-lipoprotein bind peptidoglycan to outer membrane
Term
outer membrane
Definition
-LPS
-lipoproteins
-phospholipids
-porins
Term
LPS
Definition
-lipid A
-core polysaccharide
-O antigen
Term
lipid A
Definition
-basic component
-endotoxin activity
Term
core polysaccharide
Definition
-branched 9-12 sugars
-structural
Term
O antigen
Definition
-50-100 repeating saccharide units
-allows serotype distinction
Term
mycoplasma
Definition
-have no cell wall
-plasma membrane contains sterols
Term
Archea
Definition
-may lack cell wall or are composed of polysaccharides and proteins
-pseudomurein instead of peptidoglycan
Term
plasma membrane
Definition
-thin semi permeable membrane composed of phospholipid bilayer
-polar ends form innermost and outermost
-peripheral proteins found at innner or outer surface
-integral proteins span membrane or are channels with a pore (transmembrane proteins)
Term
functions of plasma membrane
Definition
-selective semi permeable membrane that determines what goes on in and out of organism
-breakdown of nutrients
-production of energy (ATP)
Term
cytoplasm
Definition
-gel like substance
-80% water
-contains proteins, carbs, lipids, inorganic ions. low MW compounds
Term
major structures of cytoplasm
Definition
-nucleoid
-plasmids
-ribosomes
-inclusions
Term
nucleoid
Definition
-long single molecule of double stranded helical supercoiled DNA
Term
plasmids
Definition
-small molecules of double stranded helical non chromosomal DNA
-code for proteins not coded by nucleoid (antibiotic resistance, exotoxins)
Term
ribosomes
Definition
-composed of rRNA and protein
-composed of two subunits with densities of 30S and 50S
-two subunits combine during protein synthesis to make 70S
Term
inclusions
Definition
-reserve deposits
-may be starch glycogen, lipids, sulfur, phosphate
-bacteria live in competitive environment where nutrients are in short supply so they store up whenever possible
-gas vacuoles are hollow cylinders that maintain buoyancy
Term
endospores
Definition
-resistant structures formed by Gram + bacteria under adverse conditions
-most resistant life from known
-able to survive 100 degrees C for long periods
-reisistant to UV light, drying up, and harmful chemicals
-some disease organisms like anthrax and botulism form spores that reside in soil
-size shape and location are genetic characteristics
Term
formation of endospores
Definition
-spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm
-Plasma membrane starts to surround DNA, cytoplasm, and membrane isolated in step 1
-spore septum surrounds isolated portion forming an forespore
-peptidoglycan layer forms between membranes
-spore coat forms
-endospore is freed from cell
Term
NAG
Definition
N-acetylglucosamine
Term
NAM
Definition
N-acetylmuramic acid
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