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