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90 Cards in this Set

  • Front
  • Back
what are the two types of prokaryotic cell appendages?
1. Flagella (axial filaments)
2. Fimbriae (Pili)
what are bacteria that do not possess a flagella called?
non-motile
what are the exceptions to bacteria without flagella that can still move?
gliding bacteria
there are 3 parts of a eukaryotic cell?
basal body
hook
filament
what part of the prokaryotic cell is this?
associated cytoplasmic membrane and cell wall
composed rod 1&2 or sets of rings (plates)
basal body
how many plates are there in gram negative bacteria?
4
how many plates are there in gram positive bacteria?
2
are basal bodies capable of rotation?
yes
what part of the cell is this?
anchored into basal body (a short curved surface)
hook
what part of the cell is this?
inserted into hook, composed of protein subunits (FLAGELLIN)
~20 nm dia, 1-7 mm length
(H-antigen used in classification)
filament
where are flagella arranged on bacterial cells, generally?
polar ends
define: monotrichous
single flagella
define: lophotrichous
small tufts at same site
define: ambhitrichous
flagella at both poles
define: lateral flagella
around surface
define: peritrichous
flagella surrounding entire cell
what are the 4 ___taxis of how bacteria move?
chemotaxis
magnotaxis
phototaxis
thermotaxis
define: chemotaxis
chemicals
define: magnotaxis
magnetic field
define: phototaxis
light intensity
define: thermotaxis
heat
explain how a bacterial cells moves via its flagella
movement occurs through rotation of flagellar motion which is reversible motor rotates CCW direction or CW
how does a bacterial cell move forward
by CCW motion of its flagella around a common axis. The flagella collect like a pony tail.
how does a bacterial cell tumble?
by CW motion of its flagella around a common axis. The flagella also disperse like medussa
define: chemorectors
proteins detect and bind chemicals then transmit signals
where are chemorecptors located?
in the periplasmic space/ plasma space
how many chemoreceptor attractrants are there?
20
how many chemorecetors repellants are there
10
how is movement influenced from chemotaxis?
random movement
absence of concentration gradient
movement in attractant gradient
tumbling frequency reduced
how fast do bacteria move with respect to chemotaxis?
20-90 micro meters per second
~ 6ft human running 5 body lengths/second
what is the role of fimbriae?
to attach to each other and surfaces via their bristles
what type of bacteria has a F-pilis? (gram -/+ ?)
gram negative only
what are pili used for?
conjugation (bacteria sex)
define: glycolcalyx
external mucilaginous layer, surrounds cell, shows organization
how many layers is the glycolcalyx composed of?
2
slime layer
capsule
define: slime layer
abundant, easily washed off (poorly organized) biofilm
define: capsule
abundant, not easily washed off (K-antigen used for classification)
what are the purposes of glycocalyx?
provide protection from drying out
block attachment of bacteriophages
anti-phagocytic (inhibit engulment of pathogenic bacteria by WBCs)
true or false
the glycocalyx contributes to virulence infective ability?
true
what are the characteristics of a prokaryotic cell wall?
determines shape
provides support/rigidity
retains cell contents
what is the bacterial cell membrane composed of?
peptidoglycan insoluble and unique to bacteria. Is also cross-linked polymer (glycan) that provides strength and rigidity
is peptidoglycan present in all bacteria?
no, e.g. Mycoplasma sp.
how do the peptide and glycan units connect to form the peptidoglycan sheet?
N-acetyl Muramic Acid (NAM)
and
N-acetyl Glucosamine (NAG)
linked by B(1-4)glycosidic bonds
is the tetrapeptide (4 Aa's)attached to each NAM or NAG?
NAM
Where in the tetrapeptide does cross-linking occur?
the 3rd Aa of 1 tetrapeptide to the 4th Aa of another
what type of bond is between the tetrapeptide crosslinkages?
pentaglycan bridge
Who developed the gram stain?
Christian Gram 1884
What are the characteristics of a gram positive bacteria?
-large peptidoglycan content 50% of dry weight
-tightly bound ACIDIC anionic polysacc's, Teichoic acid + Lipoteichoic acid, bind protons (maintain low pH), cations (Ca2+ and Mg2+)
-acts as virus receptor sites
What are the characteristics of a gram negative bacteria?
-thin shell of peptidogycan 10% of dry weight.
-complex morphology: outer membrane (outer lipopolysacc layer and inner lipid layer)
-PORINS present
-extensive space between peptidoglycan and cell membrane
What is the function of the outer membrane?
IMPERMEABLE BARRIER prevents the escape of enzymes (periplasmic space and outer membrane)
What is Lipopolysaccharide (LPS)endotoxin composed of?
-Inner most LIPID (lipid A), anchors LPS to outer membrane
-Polysaccharide portion (external to lipid A)
-O-polysaccharide long repeating sequence of sugars (O-antigen)
Spirochetes are able to move but do not possess a flagella, so how do they move?
with an internal structure called an ENDOFLAGELLUM
what are the characteristics of an Endoflagellum?
-modified axial filaments
-long thin microfibril, inserted into a hook, entire structure enclosed in periplasmic space.
-imparts a corkscrew-like motility
What is the cell/cytoplasmic membrane composed of ?
4-5 nm thick
composed 1* phospholipid 30-40%
and protein 60-70%
what are the characteristics of the phospholipid bilayer?
polar heads (outwards into aqueous phase- membrane surface)
fatty acyl tails (inwards-semi/liquid phase of at interior)
FLUID MOSAIC MEMBRANE
what are the 2 types of proteins in the cell membrane?
integral and peripheral
How are integral proteins removed?
removed by destruction i.e. detergents
How are peripheral proteins removed?
they are loosely attached and thus easily removed i.e. osmotic shock
What are the five functions of the cytoplasmic membrane?
1. transport
2. oxidative phosphorylation
3. secrection
4. anchoring DNA
5. Metabolism
what is the purpose of transport in the cytoplasmic membrane?
to control nutrients
what is the purpose of oxidative phosphorylation in the cell membrane?
respiration
what is the purpose of secrection in the cell membrane?
discharge of metabolic products
what is the purpose of anchoring DNA in cell membranes?
to help during cell division
what is the purpose of metabolism in the cell membrane?
enzyme sites
What are the characteristics of the protoplasm of prokaryotes?
it has a granular appearance due to the free ribosomes, it is the site of biochemical activity. Water 70-80% act as solvent for nutrients, sugars, Aa and salts.
What does the chromatin area contain?
The bacterial chromosome. Remember, bacteria have no distinct membrane enclosed nucleus.
What are the characteristics of the bacterial chromosome?
-typically single stranded DNA
-all genes are linked, and aggregated into one area
What is the aggregated area of all the DNA of a bacterial chromosome called?
nucleoid
In addition to the chromosome some bacteria may contain one or more small circular pieces of DNA capable of self-replication called?
plasmids
define F-Plasmids
fertility, genes for mating in conjugation
define R-plasmids
resistance, antibiotics; metals; etc.
What are the 6 different types of plasmids?
F-Plasmid
R-plasmid
Virulence factor
Col-plasmids
Ti-Plasmids
Metabolic
what are encoded in the virulence factor plasmids?
enterotoxin (GI upset), fimbriae, antibiotic production
what is encoded in the coliciongenic (col-plasmids)?
gene for protein (COLICINS) toxic to closely related bacteria (eliminates competitors) for nutrient competition
what is encoded in the transformation (Ti-plasmids)?
plant microbiology (formation of crown fall tumors)
what is encoded in metabolic plasminds?
utilization of camphor, toulene
Where are ribosomes locate in the prokaryotic cell?
in the protoplasm
what are ribosomes composed of?
DNA/RNA bodies, composed of 2 subunits (50S + 30S= 70S) Svedburg units
where are the sites for protein synthesis in prokaryotic cells?
ribosome
do you see mesosomes in gram positive or gram negative bacteria?
only in gram positive
define: mesosome
extensive invaginations (infoldings) of cytoplasmic membrane that are continous with membrane. Function= unknown (possibly cell division)
what is the function of gas vesicles?
they are a means of motility, allowing the cells to float up and down in a water colomn in response to environmental factors.
what are the two types of vesicles?
membrane bound
and
non-membrane bound
what is the function of membrane bound vesicles?
vesicles of poly-B-hydroxybutarate, gas filled vacuoles (aquatic photosynthetic bacteria) {non-permanent structures}
what is the function of non-membrane bound vesicles?
vesicles of metachromatic (Volutin) composed of polyphosphate act as a carbon and energy source
compensate for poor availability of nutrients
define: endospores
are specialized structures that require specialized stains (light microscopy)
resistant to environmental stress; UV, irradation, chemical disinfection, drying
(Endospores are a means of survival)
what does the exterior membrane of an endospore look like ?
well-defined multilayered exosporium, electron dense outer coat, thick inner coat
what is the interior of an endospore composed of?
ribosome and nuclear material
define: sporulation
occurs when conditions are unfavorable for bacterial cell survival.
1 bacteria -> 1 spore complex process, takes hours to complete
define: germination
1 spore -> 1 bacterial cell
only occurs when conditions favorable for bacterial cell growth.