Microbial strucutre and growth Flashcards
Simple transport
a transporter that
consists of only a membranespanning protein and is typically driven by
energy from the proton motive force
group transport
an energy-dependent
transport system in which the substance
transported is chemically modified during
the process of being transported by a series
of proteins
ABC transport system
(ATP-binding cassette) transport
system a membrane transport system
consisting of three proteins, one of which
hydrolyzes ATP; the system transports
specific nutrients into the cell
Aerobe
an organism that can use O2 in
respiration; some require O2
aerotolerant aerobe
a microorganism
unable to respire O2 but whose growth is
unaffected by it
alkaliphile
an organism that has a growth
pH optimum of 8 or higher
autoclave
a sealed heating device that
destroys microorganisms with temperature
and steam under pressure
binary fusion
cell division following enlargement of a cell to twice its minimum size
biofilm
an attached polysaccharide matrix
containing bacterial cells
budding division
a cell division process
whereby new cell material is produced from
a single point instead of along the entire cell
cardinal temperatures
the minimum,
maximum, and optimum growth temperatures for a given organism
compatible solute
a molecule that is
accumulated in the cytoplasm of a cell for
adjustment of water activity but that does
not inhibit biochemical processes
extreme halophile
a microorganism that
requires very large amounts of NaCl, usually
greater than 10% and in some cases near
saturation, for growth
facultative
with respect to O2, an organism that can grow in either its presence or
absence
generation time
the time required for a
population of microbial cells to double
halophile
a microorganism that requires
NaCl for growth
halotolerant
tolerates salty environments
hyperthermophyle
a species of Bacteria or
Archaea whose growth temperature optimum is 80°C or greater
mesophyle
an organism that grows best at
temperatures between 20 and 40°C
microaerophile
an aerobic organism that
can grow only when O2 tensions are reduced from that present in air
MIC (minimum inhibitory concentration)
the minimum concentration of a
substance necessary to prevent microbial
growth
neutrophile
an organism that grows best at
neutral pH, between pH 5.5 and 8
obligate anaerobe
an organism that cannot
grow in the presence of O2
osmophile
an organism that grows best in
the presence of high levels of solute, typically a sugar
psychrophyle
an organism with a growth
temperature optimum of 15°C or lower
and a maximum growth temperature
below 20°C
psychrotolerant
capable of growing at low
temperatures but having an optimum
above 20°C
thermophile
e an organism whose growth
temperature optimum lies between 45
and 80°C
water activity
the ratio of the vapor pressure of air in equilibrium with a solution to
the vapor pressure of pure water
xerophile
an organism that is able to
live, or that lives best, in very dry
environments
acidophyle
an organism that grows best at
low pH, typically below pH 5.5
catabolism
energy production
metabolism
sum of all chemical reactions in a cell
anabolism
uses energy to produce biomass
chemoorganotroph
oxidation organic compounds
chemolithotroph
oxidation inorganic compounds
morphology influences
nutrient uptake, swimming motility, gliding motility
morphology
cell size and shape
motility
gliding, swimming, swarming
physiology
temperature, pH
cell lipid chemistry
fatty acids, polar lipids, respiratory quinones
cell wall chemistry
peptidoglycan, amino acid crosslinks
ecosystem
all living organisms plus physical and chemical constituents of environment
bright field
specimens visualized by differences in contrast surroundings
Transmission electron microscopy (TEM)
Specimen must be very thin and stained with high atomic
weight substances to improve contrast, negative staining allows direct observation of intact cells/component
Scanning electron microscopy (SEM)
only surface visualised
cell envelop
everything outside cytoplasmic membrane
archaeal membrane
ether linkages phospholipids (not ester), isoprences (not fatty acids)
symport
solute and H+ cotransported in one direction
antiport
solute and H+ transported opposite direction
ABC system
ATP and protein needed, Gram- employ periplasmic binding proteins, Gram+ and Archaea employ substrate-binding
proteins on external surface of
cytoplasmic membrane
Gram - cell wall
peptidoglycan and outer membrane
Gram + cell wall
thick peptidoglycan layer
S layer
outer most layer, Molecular sieve, attachment, protection
(Archaea: structural strength (cell wall))
Capsules and slime layers
Functions
▪ assist in attachment to surfaces
▪ role in development and maintenance of biofilms
▪ contribute to infectivity (protection against phagocytosis)
▪ prevent dehydration/desiccation
Fijmbriae
stick to surfaces
Pili
ypically longer, and fewer (1 or a few) found per cell
– Conjugative pili facilitate genetic exchange between cells (conjugation)
– Type IV pili adhere to host tissues and support twitching motility
Hamus
grappling hooks, assist in surface
attachment, forming biofilms, archaea
cell inclusions
energy reserves,
carbon reservoirs, and/or have special functions, Enclosed by thin membrane, reduce osmotic stress
carbon storage polymers PHB
lipid polymers, produces upon carbon exces s under though conditions
glycogen
glucose polymere, storage
polyphosphate granules
store inorganic phosphate
carbonate minerals
biomineralization of barium, strontium, calcium,
magnesium
magnetostomes
magnetic iron oxides; allow cell to undergo
magnetotaxis: migration along magnetic field lines
endospores
Highly differentiated cells resistant to heat, harsh chemicals, radiation
endospore steps
– activation: physical (heat) or chemical (nutrients) activator
– germination: rapid (minutes), loss of refractility and loss of
resistance to heat and chemicals
– outgrowth: swelling from water uptake and synthesis of RNA,
proteins, and DNA
endospore feaures
- many layers: exosporium (outermost), spore coats, cortex, core
- enriched in Ca 2+ and dipicolinic acid (DPA):
bind water (dehydration) and stabilize DNA - core contains small acid-soluble spore proteins (SASP):
bind & protect DNA and function as
carbon and energy source for outgrowth
archaella
flagellum in archea, smaller
twitching motility
IV pili extend and retract
glyding motility
bacteria only, intercellular helical protein structure, pmf energy, cell rotates
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
nucleus eukarya
– Contain a double membrane-enclosed nucleus
– Other organelles include mitochondria, Golgi complex, lysosomes,
endoplasmic reticula, microtubules, and microfilaments
– Some have motility (flagella or cilia)
– Some have cell walls
– Membranes contain sterols
▪ structural strength
mitochondria
– respiration and oxidative phosphorylation for aerobic eukaryotes
– few to 1000+ per cell
– surrounded by two membranes
– cristae: folded internal membranes
▪ contain enzymes needed for
respiration and A T P production
– matrix: innermost area of mitochondrion
▪ contains citric acid enzymes
chloroplasts
double membrane, thylakoids: flattened membrane discs
contain chlorophyll and ATP synthetic
components, form proton motive force
microtubules
▪ hollow tubes 25 nm in diameter; composed
of α- and β-tubulin
▪ maintain cell shape, facilitate motility;
move chromosomes and organelles
microfilaments
▪ 7 nm in diameter; polymers of actin protein
▪ maintain and change cell shape; involved
in amoeboid motility and cell division
intermediate filaments
▪ 8–12 nm in diameter; fibrous keratin proteins
▪ maintain cell shape and position organelles
