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109 Cards in this Set
- Front
- Back
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Cocci
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Spherical
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Bacilli
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Rod-like
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Vibrios
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Comma-shaped
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spirilla
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spirals
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spirochete
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tight spirals, corkscrew
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pleomorphic
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No definite shape. Can occur when there is no cell wall.
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Diplo
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The term used when cells stick together after dividing.
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strepto
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Bacteria found in chains.
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staphlyo
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Grape-like structures
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filaments
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Like chains, but have branches.
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What are the size ranges for microbes?
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.05 µm in diameter (cannot be seen in lght microscope) and can be as long as >500 µm.
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E. coli is a typical....
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bacillus at 1.3 µm. (Can be 1.2 depends on what type and growth)
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What is the microbial envelope?
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It contains all of the outside layers starting from the cytoplasm to the outermost layer.
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Microbial Envelope contains...
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plasma membrane (aka cytoplasmic membrane, PM or CM) and cell wall
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Cell wall is made of....
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murein (at type of peptidoglycan) and sometimes S-layer
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What is the difference in a Gram Negative microbial envelope?
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It has a plasma membrane, then peptidoglycan lining, then a cell wall with an outer lining that has a periplasmic space.
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Basic structure of plasma membrane
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Phospholipid bilayer (glycerol heads with two fatty acid tails)
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What are hopanoids?
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Structures that look similar to cholesterol found between the phospholipid bilayer. Makes the membrane more fluid. Act as fluidity buffers.
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How do hopanoids help in hot and cold weather?
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In extreme heat they keep the membrane together. In cold they keep the lipids fluid.
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How is the level of cytoplasmic membrane fluidity determined by?
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Level of saturation with fatty acids. Increase in double bonds means more fluid.
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If temperature cools down for plasma membrane...
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Insert more hopanoids, more double bonds into fatty acids.
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If temperature heats up for plasma membrane...
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Remove double bonds.
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Where is murein found?
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Only bacterial cell wall.
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What is murein?
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Peptidoglycan that consists of layers (glycan part is a polysaccharide where one subunit containing NAM-NAG is linked head to tail with another NAM-NAG and it continues.)
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What cleaves between the NAM-NAG bonds?
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Lysozyme
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Each NAM has what?
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A short peptide that can be cross linked to another NAM short peptide on an adjacent layer (by transpeptidase).
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Structure of Murein in Gram positive.
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NAM---L Ala---D Glu---DAP---D Ala
No use of interbridges just DAP linked to D Ala. Much fewer layers. |
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Structure of Murein in Gram negative.
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NAM---D GluNH2---L Lys---D Ala
D Ala linked to L Lys by using Gly peptide interbridge. Use of many layers. |
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What does the Gly interbridge allow?
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Flexibility, rotation, fluidity, movement. Cell wall would be too rigid without them.
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What are techoic acids?
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Can attach to NAM. Have an overall negative charge and pass this along to cell wall. Covalently attached to cell wall.
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Lipotechoic acids
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Covalently attached to cytosplasmic membrane (longer than techoic acids).
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In hypotonic situations,
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both Gram + and - protect cells from swelling excessively.
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In inner leaflet of the outer membrane of Gram negative is _______.
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contiguous, or a continuation of the outer leaflet of the cytoplasmic membrane.
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_________ is the major component of the outer leaflet of the outer membrane in Gram negative.
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Lipopolysaccharide (LPS)
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Parts of LPS
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1. Lipid A - Fatty acids attached to GlCN (Glucosamines with phosphates).
2. Core polysaccharide 3. O antigen (or side chain) |
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Lipid A
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AKA endotoxin. It is responsible for septic shock associated with Gram - bacterial infections.
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Which membrane is more permeable in Gram negative?
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Outer membrane is more permeable than plasma membrane. Due to porins, anything <700 MW can be passed.
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What are S-layers?
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The outermost layer in the envelopes of some bacteria and archaea (both gram - & +). They are self assembling, crystalline structures of a single protein or glycoprotein.
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What does the S-layer do in some cases of archae?
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It replaces the cell wall.
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How does campylobactor use S-layers?
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It's found on poultry and when you ingest it, it uses the S-layers to shield itself from our immune system.
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Capsules and slime layers are...
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extracellular structures (non envelope) composed of high MW polysaccharide or polypeptide.
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Functions of capsules.
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Protection from immune system, protection against dessication, important virulence factor.
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Examples that have capsules.
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Polysaccharides: K or S pneumoniae
Polypeptide: B anthracis |
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Funtions of slime layers.
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Attachment, and in some species used as a gliding motility
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_________ never make slime layers.
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Polypeptides.
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Glycocalyx
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The region of slime found between slime producing organisms.
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Archeal cell walls are....
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Non-murein, highly variable in structure.
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Cytoplasmic membranes for archaea.
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They contain branched lipids derived from isoprene, that are ether linked to glycerol phosphates.
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Gram negative archaea does not contain....
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LPS in the outer membrane.
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Hypothermophiles
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live stable at high temperatures.
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How do hypothermophiles stabilize themselves?
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They covalently attach them in the middle so the two leaflets of the membrane can't come apart. Also called C40 monolayers. They also include small cyclic isoprene structures that can help control fluidity.
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Archaea can use what in their cytoplasmic membranes?
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C40 monolayers and lipid bilayers, but only in temperatures from 50-70.
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Two types of prokaryotic appendages.
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Flagella and Pili (fimbriae)
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chemotaxis
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movement towards or away from certain molecules.
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When are flagella used?
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In the most common form of prokaryotic movement, chemotaxis (towards or away a molecule).
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When are Pili (fimbriae) used?
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Mainly for adhesion, but may be used along with slime production to create a type of twitching motility (non-directed) on solid surfaces in a few species.
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How are flagella and pili used to classify microbes?
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Based on type and numbers.
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Monotrichous polar flagellation (example and definition)
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Pseudomonas; one flagella at end of cell
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Lophotrichous flagellation (example and explanation)
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Spirillum; tuft (or many) flagella at one end of cell
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Peritrichous flagellation (example and explanation)
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Proteus vulgaris, or E. coli; flagella all around the cell
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Flagella are...
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semi-rigid, multi-component structures found in both Gram positive and Gram negative cells.
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How are flagella anchored?
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By rings assembled in each layer of the cell envelope (basal body)
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In Gram negative, where are the ring locations?
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MS ring - Cytoplasmic membrane.
P ring - Cell Wall (P for peptidoglycan) L ring - Outer membrane (L for LPS) Hook and filament outside, pointed away from the cell. |
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How are flagella assembled?
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From the inside out via hollow internal tube-like structure
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In Gram positive, where are the ring locations?
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MS ring in the cytoplasmic membrane.
Broad P ring in Cell wall. No L ring (no LPS). |
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What is a flagella filament made of?
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flagellin subunits (H antigens used for classification)
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Each flagella is ______ and movement occurs by...
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semi-rigid; turning the whole structure (propeller mechanism).
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What generates the torque (force) to move the flagella?
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By moving protons into the cell (protonmotive force). This ocurs via the Mot proteins.
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What determines the flagella's clockwise or counterclockwise motion?
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Fli proteins
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Counterclockwise and clockwise mean what direction?
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CCW means forward. CW means backwards or tumble.
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In chemotaxis, movement is a response to.....
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concentrations of repellents or attractants in the environment.
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Type of flagella in spirochetes.
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Endoflagella
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How is the endoflagella of spirochetes assembled?
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It is an axial filament and is when the fibrils wrap around the cell in the periplasmic space.
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How does endoflagella move?
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when the flagella rotates, the spirochetes move in a corkscrew motion, allowing them to invade deep into tissues.
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Types of spirochetes
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Treponema pallidum (syphillus) and Borrelia burgdorferi (Lime disease)
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Pili are...
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short filamentous surface structures (usually in Gram negative microbes).
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Biofilms
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when microbes attach to other microbes they make these multicellular communities.
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Sex pilus is used....
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in conjugation. One long pilus connects two microbes and the exchange genetic material.
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Pili are used in ....
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pathogenesis. Usually harmful microbes are swept away by our cilia, but pili allow them to attach strongly to parts of our body.
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How are pili used in motion?
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They aren't used for locomotion. Only some use a non-directed crawling motion called twitching motility.
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Filaments of pili are made of
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proteins called pilins.
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Nucleoid
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What prokaryotes have instead of a nucleus. Where the chromosome is condensed by proteins. Transcription and translation can occur simultaneously here.
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Prokaryotes typically have
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a single circular chromosome, no nuclear membrane.
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Plasmids
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extra-chromosomal circular DNA that replicate autonomously in the cytoplasm. Size varies from 1kb to 1000kb.
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Conjugative plasmids phenotypic features
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sex pilus, conjugation
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R plasmids phenotypic features
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sex pilus, conjugation, resistance to antibiotics,
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Col plasmids phenotypic features
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colicin production
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Virulence plasmids phenotypic features
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enterotoxin production, tumor induction in plants
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Metabolic palsmids phenotypic features
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degradation
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Prokaryotic cytoplasm is packed with _____ribosomes.
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10^4 - 10^5/cell.
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Prokaryotic ribosomes
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1. consist of 2 subunits (large and small)
2. functionally similar but structurally different than eukaryotic ribosomes 3. differentially inhibited by antibiotics |
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Eukaryotic cells contain _________ in the mitochondria and chloroplasts.
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Prokaryotic type ribosomes
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Prokaryotes have _________ analogous to those found in eukaryotes.
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cytoskeletal elements
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Prokaryotic protein, it's eukaryotic counterpart, and it's function. (Hint: there is three)
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1. FtsZ; tubulin; celldivision
2. MreB; actin; cellshape 3. Crescentin; intermediate filament proteins; cell shape |
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Fluorescence microscopy
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Tagging actin like proteins with GFP (Green Fluorescent Protein) used to look at live cells.
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Gas vesicles are found....
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in both bacteria and archaea (usually photosynthetic organisms).
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Purpose of gas vesicles...
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to confer buoyancy,
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Gas vesicles on size and number.
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The vary in both.
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PHA's are commonly formed and used for...
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storage of excess fuel molecules.
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The most commone PHA.
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PHB (Poly-Beta-hydroxybuterate)
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PHA's are enclosed in....
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lipid membrane to form storage vesicles
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Phosphate and sulfur are stored in....
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granules.
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Magnetosomes:
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1. Contain Oxides or sulfides
2. Work as magnets & align to earth's magentic pole 3. Surrounded by invaginations of cytoplasmic membrane. |
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Carboxysomes:
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contain high levels of enzymes used to "fix" CO2.
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Eterosomes:
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1. Found in "enteric" (gut) bacteria
2. Contain high levels of specific enzymes involved in special metabolic pathways in enteric bacteria. |
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Location of endospores:
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terminal, subterminal, or central.
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Endosporulation
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1. the process of producing an endospore.
2. occurs when the cell cannot survive. |
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Endospores are resistant to:
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dessication, heat, radiation, chemicals, & can survive for centuries or longer.
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How do endospores tolerate so much in resistance?
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-high levels of calcium, dipicolinic acid, and SASPs that bind and protect DNA
- low water - metabolically inactive |
