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Compare/contrast prokaryotic and eukaryotic cells
- Prokaryotic cells (bacterial cells)
- . No nucleus
- Nucleoid Region.
- binary Fission.
- 70s ribosomes.
- cell size and shape (smallest organisms) include; Coccus, Bacillus, Coccobacillus, Vibrio, spirillum, Spirochete).
- cell wall (movement of substances across membranes).
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Compare/contrast prokaryotic and eukaryotic cells
- Eukaryotic cells.
- has a nucleus (plants, animal, fungi, and protoza.
- Membrane-bound organelles.
- mitosis & meiosis.
- reproduce sexually.
- 80s & 70s ribosomes
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Compare/contrast prokaryotic and eukaryotic cells
Both have cell walls or plasma membrane.
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What are possible shape of Prokaryotic cells?
- Coccus(s), Cocci (pl.); sphenical round.
- bacillus (s), bacilli (pl.); rods.
- Vibrio; curved.
- spirillum; wavy.
- spirochete; cork crew
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What is pleomorhusm?
Baceria that vary widely in form (shape) even w/in a single culture.
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What are the possible arrangements of bacterial cells?
- diplo=pairs.
- stepto=chains.
- tetrads=four cells cube.
- garcinae= eight cells arranged in a cube.
- staphlo= grape shaped
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Steptococcus tells you what about the organism?
steptococcus translates into chains of special bacteria.
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How are the arrangements formed?
in chains
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What are the function of the bacterial cell wall?
- 1st Maintain shape of the cell.
- 2nd Prevent cell from bursting when fluid flow into cell by osmosis.
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What is the major component of the bacterial cell wall?
Major component is peptidoglycan. It is a large polymer thought of as one immense covalently linked molecule.
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How does the cell wall determine gram neg or pos. bacteria?
- G+ has a thick (40) layer peptidoglycan.
- third Amino Acid is lysine.
- teichoic acid
- G- has a thin layer.
- diaminopimelic acid
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What is a outer membrane?
Primay G- a bilayer membrane. Outer most layer of the cell wall attached to pepidoglycan by and almost continous layer of small lipoprotein molec. contains lipopolysacchard (endotoxin) identifis G-, LPs contains polysacchards and lipids A.
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What is it composed of?
Lipopolysaccharide (polysaccharides and lipid A)
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What is endotoxin?
Lipopolysaccharide (polysaccharide) released when cell wall of dead bacteria are broken down.
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In which bacterial cells do you find on OM?
G-.....G neg.
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What is the periplasmic space?
Gap between cell membrane and peptidoglycan.
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Which cells have the periplasmic space?
---> gap observed by electron microscopy of G neg bacteria.
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Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
G pos; Thick layer of peptidoglycan. Have little amount of protein cell, cell wall retain chrystal violet stain. Lacks both outer membrane and a periplasmic space.
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Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
G neg; cell wall thinner more complex than G+. cell membrane consistis of polysaccharides protein & lipids. Cell wall contains outer membrane & periplasmic space. Have lipo proteins and lipopolysaccharide in their walls.
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Compare/contrast the cell wall of gram +,gram -,and acid-fast bacteria?
- Acid- fast bacteria; cell wall (mycobacteria) thick 60% lipids less peptidoglycan. Carbolfuchsin binds to cytoplasm (resists removal by an acid-alcohol mixture).
- Lipids make impermeable to stains, protects from acid and alkalis slows growth because lipid impermeable nutrients.
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What organism have no cell walls?
- mycoplasm genus bacteria.
- shape pleomorhism (deficent strains are called L-form).
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Describe the fluid-mosaic model of the cell membrane?
A phospholipid bilayer has two long fatty acid tail of hydrocarbon they are hydrophobic the head of the molecule consists of a charged phosphate group usually joined to charged nitrogen containing group. Head is hydrophilic.
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How are the phospholipids arranged?
Phospholipids form a bilayer or two adjacent layers phosphate ends of lipid molecules extends towards the membrane surface and fatty acid ends extend inward.
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Define diffusion
- Simple diffusion; is the net movement of particles from a region of higher to lower concentration.
- facilitated diffusion; diffusion down a concentration gradient and across a membrane with the assistance of special pores or carrier molec.
- osmosis; a special case of diffusuon in which water molecules diffuse across a selectively permeable membrane.
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What is osmotic pressure ?
- Pressure at is required to prevent the net flow of water by osmosis.
- The least amount of hydrostatic pressure required to prevent the movement of water from a given solution into pure water is osmotic pressure.
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define hypotonic
hypotonic; water moves into cell
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define hypertonic
hypertonic is water moves out of cell.
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define isotonic
isotionic is water moves out and in equally.
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how will a bag or a cell behave in each type of solution and what way will the water flow?
- Hypotonic water flows into the bag and will cause it to swell & burst.
- Hypertonic water flows out of the bag and will cause it to shrivel.
- Isotonic water flows equally and retains the same shape.
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Define active transport
- Carrier protein molec aid in movement of molec against a concentration gradient.
- *requires ATP and membrane proteins.
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Compare/contrast the ribosomes in prokaryotic vs. eukaryotic cell
Eukaryotic ribosomes are 60% RNA & 40% protein larger than prokaryotic. Have a sedimentation rate of 80s subunits have sediment rates of 60s & 40s assembled in the nucleoli of nucleus. Prokaryotic & eukaryotic ribosomes provide sites for protein synthesis some are chains as polyribosomes. Free floating ribosomes make protein for use in cells.
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what are the clinical applications that exploit this difference?
Antibiotics such as streptomycin & erythromycin bind to 70s ribosomes specifically & disrupt bacterial protein synthesis w/out harming Eukaryotic host which mostly has 80s ribosomes.
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What is the nucleoid region?
Also known as nuclear region of DNA but has some RNA and protein associated with it. May contain chromosomes and plasmids.
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Generally what is the characteristics of bacterial chromosomes?
One large circular chromosomers, two circular chromosomes on circular and 1 linear chromosomes circular molec. of DNA called plasmids.
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What are plasmids and how are they used?
Plasmid are smaller circular molec. of DNA. They contain genetic information in plasmids supplement info in the chromosomes.
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What are endospores and what is their purpose?
- A special struture found in bacteria (Bacillus sp. & Clostridium sp.)
- *Requires time and energy to make spores
- **Helps the bacterial cell to survive when conditions become unfavorable
- ****resistant to heat, drying, acids, bases, certain disinfectants and radiation
- ******known to be remain dormant for 10,000yrs.
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What are flagella, and how might they be arranged?
- Flagella are long thin helical appendages that make bacteria motile.
- Arrangements include
- monotrichous: one end (polar).
- anphitnchous: one at each end (polar).
- Lophotrichous: tuft of flagella at one or both ends.
- Peritrichous: flagella all over the surface.
- Atrichous: no flagella (no motility)
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How are flagella anchored in gram-positive and gram-negative bacteria?
G-neg bacteria have a pair of rings embedded in the cell membrane and another pair of rings associated with peptidoglycan & lipopolysaccaride layers of the cell wall. G+ pos. bacteria have one ring embedded in the cell membrane and another in the cell wall.
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Flagella in Eukaryotic cells?
- Longer and more complex than those of prokaryotic cells. Constist of two central micro tubules and 9 pairs of peripheral microtubules surrounded by a membrane. Each fiver is a microtubule made of the protein tubulin. Move like a whip.
- Found mostly in protozoa. Most have one flagella some have 2 or more.
- spermatozoa is the only human flagellated cell..
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Describe a run and tumble
- When flagella of a bacteria rotate counter clock wise.
- Direction the flagella bundle together and push the bacterium fairly strait this is the run.
- Reverse & rotate in a clockwise direction the bundle comes apart each flagella acts independantly.
- The cells tumble about in randum direction= tumble.
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What is chemotaxis?
- Pos./neg chemotaxis.
- movement toward or away from a substance in their environment.
- Toward is an attrachtant; positive
- Away is repleant; negative
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What is phototaxis?
- Some bacteria can move toward or away from the light.
- Pos. phototaxis is toward light.
- Neg. phototaxis is away from light
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What are pili and how are they used ?
- Pili are tiny hollow projections.
- They attach bacteria to surfaces.
- Do not movement.
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How are pile used in conjugation?
- Long conjugation pili (F-pili):
- tube in which DNA is transferred form one cell to the next.
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How are pili used in attachment?
- Attachement pili or fimbriae;
- help bacteria to adher to surfaces such as cell surphases and the inter faces of water and air contribute to pathogenicity of certain bacteria.
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How are pile used in pellicle?
- Some aerobic bacteria form a shiny of fuzzy thin layer at the water/air interface of a broth culture.
- This layer is the pellicle.
- Consist of many bacteria that adhere to the surface by their attachment pili.
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Glycocalyx
refers to all polysaccaride - containing substanced found external to the cell wall from the thickest capsule to the thinnest...slime layer.
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What is a capsule and why are encapsulated bacteria more difficult for their host to fight?
- A capsule is a protective structure outside the cell wall of the organism that secretes it.
- Capsules prevents host defense mechanism such as phagocytosis from destroying the bacteria.
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What is a slime layer and function?
- A less tightly bound to the cell wall and is usually thinner than a capsule.
- Protects cell from drying out, traps nutriunts near the cell.
- Sometimes bind cells together.
- Slime lalyer allow bacteria to adhere to objects in their environments, such as.
- rock surface.
- root hairs of plants
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List Eukayotic cells
- Nucleus.contain RNA that assembles ribosomes.
- Have chromosomes that contain DNA.
- Golgi apparatus.Stores, transports and receives substances form the er packages.
- Ribosomes.Provide site for protein synthesis.
- Endoplasmic reticulm.smooth ER, synthesizes lipids, Rough ER manufacture proteins.
- vacuoles.store starch glycogen or fat for energy.
- mitochondria.carry out the oxidative rxn that capture energy in ATP
- Cytoplasm.semifluid substance consisting mainly of water.
- Chloroplast.carrys out photsynthesis.
- lysomes.fus w/vacuoles and release enzymes to digest the substance inthe vacuoles.
- peroxisomes.filled w/enzymes that oxidize AA in animals cells and fats in plant cells.
- Cytoskeleton.network of protein fiber microtubles and microfilaments that supports and gives ridgity to cells
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What are celia?
- Cilia are shorter and more numerous than flagella, mainly in protozoa passes thru strokes and recovery cycle.
- Propell's fluids and dissolves particles of bacteria mucus.
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What is pseudopodia?
- False feet.
- temporary projections of cytoplasm associated w/amoeboid movement. occurs oily in cells w/o walls.
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Explain the endosymbiotic theory
Organelles of eukaryotic cells arose form prokaryotic cells that had developed a symbiotic relationship w/the eukaryotic to. When one organism lives inside another organism not just close contact.
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What evidence supports this theory about the endosymbiatic theory?
- Mitochondria and chloroplast; same size as prokaryotic cells and have own DNA.
- Organelle DNA & ribosomes carry out protein synthesis as it occurs in bacteria.
- Antibiotic inhibiting protein synthisis in bacterail ribosomes also inhibit it in ribosomes of chloraplasts and mito.
- mito. and chloro divide indepentality of cell by means of binary fission.
- Double membrane structure of mito & chloro resemble syanobacteria.
- Mito DNA resemble DNA of rickettsia.
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What example found of endosymbiotic theory in nature?
- Certain eukaryotes living in low-oxygen enivonments lack mito yet they have bacteria that live inside them and serve as surrogates mito.
- Protist live symbiotically in lermite termites guts in torn colonized by symbiotic bacteria of the same size and distribution they frunction better in low O2 conditions better that mito
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Endocytosis
- made from portions of plasma membrane.
- form invanation & surround substances from outside cell and enter the cell
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Exocytosis
vesicles inside cell fuse w/plasma membrane and extrude their contents.
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