Lecture 5 Flashcards
glycol tetrapeptide
structure of repeating unit in peptidoglycan found in coli and most gram neg. bacteria
glycol tetrapeptide repeating units
N-acetylglucosamine and N-acetylmuramic acid
glycosidic bonds
X direction
peptide bonds
Y direction
Gram pos. cells walls can contain up to ___%peptidoglycan
90%
Gram pos. cell walls are common to have ____________ embedded in their walls.
teichoic acids
lipoteichoic acids
teichoic acids covalently bound to membrane lipids
Examples of prokaryotes that lack cell walls?
- mycoplasmas
- thermoplasmas
mycoplasmas
group of pathogenic bacteria
thermoplasma
species of archaea
Gram geg. bacteria walls contain ___% peptidoglycan.
10
Most of the cell wall of gram neg. bacteria walls are composed of…
lipopolysaccharide (LPS) layer
LPS consists of…
core polysaccharide and O-polysaccharide
LPS replaces most phospholipids in the….
outer half of outer membrane
endotoxin
the toxic components of LPS
Lipid A
releases endotoxin when gram neg. cells are lysed
periplasm
gel like consistency space located between cytoplasmic and outer membranes that houses many proteins
How wide is the periplasm
~15nm
porins
channels for movement of hydrophilic low-molecular-weight substances
Archaea has no…
peptidoglycan and outer membrane
pseudomurein
- polysaccharide similar to peptidoglycan composed of N-acetylglucosamine and N-acetylalosaminuronic acid
- found in cell walls of certain methanogenic archaea
T/F all archaea cell walls contain pseudomurein
some cell walls lack pseudomurein
S layers
- present outside other layers of the cell wall
- not in all species
- made of protein
Archaea and the S layer
In some archaea, the S layer is the only cell wall
Capsules and slime layers are made of…
carbohydrate polymers
Capsules and slime layers….
- assist in attachment to surfaces
- protect against phagocytosis
- resist desiccation
fimbriae
-filamentous protein structures that enable organisms to stick to surfaces or form pellicles
pili
filamentous protein structures typically longer than fimbriae
What do pili do
- assist in surface attachment
- facilitate genetic exchange between cells
- motility
Which pili is involved in twitching motility
type IV
conjugation
facilitate genetic exchange between cells
polyphosphates
accumulations of inorganic phosphate
sulfur globules
composed of elemental sulphur
carbonate minerals
composed of barium, strontium, and magnesium
magnetosomes
can orient themselves specifically within a magnetic field
gas vesicles
spinal-shaped, gas filled structures made of protein that confer buoyancy in planktonic cells by decreasing cell density
-impermeable to water
gas vesicles are composed of which two proteins?
GvpA and GvpC
endospores
dormant, highly differentiated cells resistant to heat, harsh chemicals and radiation
Ideal dispersal of endospores
via wind, water, or animal gut
Endospores are present only in..
some gram pos. bacteria
types of endospores
terminal, subterminal, and central
endospore structure
- contains dipicolinic acid
- enriched in Ca2+
- core contains small acid-soluble spore proteins (SASP)
Spore formation is…
highly regulated
flagella
assists in swimming moving by rotation
-helical in shape
different flagellar arrangements
peritrichous, polar, lophotrichous
flagella composed of..
flagellin
flagellar structure of archaea
- half the diameter of bacterial flagella
- composed of several different proteins
- move by rotation
flagellar synthesis in bacteria
- several genes required
- MS ring made first
- then proteins and hook
- filament grows from tip
Flagella increase or decrease rotational speed in relation to strength of the….
proton motive force
Differences in swimming motions
- peritrichous: move slow in straight line
- polarly flagellated: move more rapidly and typically spin
gliding motility
- flagella-independent motility
- slower and smoother than swimming
- movement along long axis of cell
- requires surface contact
mechanisms of gliding motility
- excretion of polysaccharide slime
- type IV pili
- gliding-specific proteins
taxis
directed movement in response to chemical or physical gradients
chemotaxis
response to chemicals
phototaxis
response to light
aerotaxis
response to oxygen
osmotaxis
response to ionic strength
hydrotaxis
response to water
chemotaxis attractants and receptors sensed by..
chemoreceptors
