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Chapter 4 Prokaryotic and Eukaryotic Cells

Functional Anatomy of Prokaryotic and Eukaryotic Cells
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Word origins of Prokaryote and Eukaryote
Comes from the Greek words for prenucleus and true nucleus respectively.
Traits of Prokaryotes
One circular chromosome, not in a membrane; No histones, no organelles, Bacteria: peptidoglycan cell walls; Archaea: pseudomurein cell walls; binary fission
Traits of Eukaryotes
Paired chromoseds in a nuclear membrane; histones; organelles; polysaccharide cell walls; mitotic spindle
Traits of Prokaryotes
Average size of 0.2-1.0 micronmeters x 2-8 micrometers; monophorphic; a few pleomorphic
Basic Shapes of Prokaryotes
Bacillus(Rodlike); Coccus(spherical); Spiral(spirillum, vibrio, spirochete)
Three Arrangements of Bacteria
Pairs(diplocci, diplobacilli); Clusters(staphylococci); Chains(streptococci, streptobacilli)
Glycocalyx
Outside the cell wall usually sticky; capsule is neatly organized; has a slime layer that is unorganized and loose; extracellular polysaccharide allows cell to attach; capsules prevent phagocytosis
Flagella
Outside cell wall; made of chains of flagellin(protein) attached to a protein hook; anchored to the wall and membrane by the basal body
Motile Cells
Rotate flagella to run or tumble; move toward or away from stimuli(taxis); Flagella proteins are H antigens(antigen = anything that can fight an antibody)
Axial Filaments
Also called endoflagella; in spirochetes; anchored at one end of a cell; rotation causes cell to move
Fimbriae and Pili
Hollow tube like structures; Fimbriae used to attach to things; Pili are used to facilitate transfer of DNA from another cell and for gliding and twitching motility
Cell Wall
Prevents osmotic lysis(breaking down); made of peptidoglycan(in bacteria)
Composition of Peptidoglycan
Polymer of disaccharide: N-acetylglucosamine(NAG) and N-acetylmuramic acid(NAM)
Peptidoglycan in Gram-P Bacteria
Linked by polypeptides
Primary Characteristics of Gram-P Cell Wall
Thick peptidoglycan; Teichoic acids; 2 ring basal body; Disrupted by lysozyme(enzyme that disrupts pepidoglycan); Penicillin sensitive
Primary Characteristics of Gram-N Cell Wall
Thin peptidoglycan; Outer membrane; Periplasmic space; 4 ring basal body; Endotoxin; Tetracycline sensitive
Functions of Gram-P Cell Wall
Contains Teichoic Acids such as Lipoteichoic acid and links to plasma membrane also Wall teichoic acid links to peptidoglycan; Cell wall may regulate movement of cations; Polysaccharides provide antigenic variation
Gram-N Outer Membrane
Lipopolysaccharides, lipoproteins, phospholipids; Forms the periplasm(contains peptidoglycan layer) between the outer membrane and the plasma membrane;
Provides protection from phagocytes, complement(things body uses to kill) and antibiotics; O polysaccharide antigen, e.g. E. coli 0157:H7; Lipid A is an endotoxin; Porins(proteins) form channels through membrane
Gram stain mechanism
Crystal violet-iodine crystals form in cell; Gram-P has alcohol dehydrating peptidoglycan and CV-I crystals do not leave
Gram-N Alcohol dissolves outer membrane and leaves holes in peptidoglycan and CV-I washes out
Atypical Cell Wall Characteristics(Acid Fast)
Acid-fast cell walls like gram-p cell walls; waxy lipid(mycolic acid) bound to peptidoglycan; Mycobacterium(pathogen:leprocy) Nocardia
Atypical Cell Wall Characteristics(Mycoplasmas)
Lack cell walls and therefore pleomorphic and contains sterols in plasma membrane;
Atypical Cell Wall Characteristics(Archaea)
Wall-less or walls of pseudomurein (lack NAM and D-amino acids)
Cell Wall Damage
Lysozyme digests disaccharide in peptidoglycan; Penicillin inhibits bridges in peptidoglycan; Protoplast is a wall-less cell; Spheroplast is a wall-less gram-p cell. Both are susceptible to osmotic lysis; L forms are wall-less cells that swell into irregular shapes
Plasma membrane composition
Phospholipid bilayer; Peripheral proteins, Integral proteins; Transmembrane; Proteins; Sterols(Eukaryotes have most bacteria don't)
Glycocalyx carbohydrates
Fluid Mosaic Model
Membrane is as viscous as olive oil; Proteins move to function; phopholipids rotate and move laterally
Plasma membrane Functions
Selective permeability allows passage of some molecules; enzymes for ATP; Photosyntethic pigments on foldings called chromatophores or thylakoids
Simple and facilitative diffusion, Osmosis, Active Transport
Endocytosis both Phagocytosis(pseudopods extend and engulf particles) and Pinocytosis(membrane folds inward, bringing in fluid and dissolved substances)
Plasma membrane damage
Damage to the membrane by alcohols, quaternary ammonium(detergents), and polymyxin antibiotics causes leakage of cell contents
Movement of Materials across membranes
Simple diffusion: movement of a solute from high concentration to low;
Facilitated diffusion: solute combines with a transporter protein in the membrane(uses no energy goes through pore)
Osmosis: movement of water across a selectively permeable membrane from high concentration to low
Osmotic pressure: pressure needed to stop the movement of water across membrane
Movement goes through lipid layer and aquaporins(water channels)
Active Transport: requires a transporter protein and ATP(allows for low to high movement)
Group translocation: requires a transporter protein and PEP(moves more than one molecule at a time)
Isotonic
No net movement of water occurs
Hypotonic
Water movesinto the cell. If the cell wall is strong, it contains the swelling. If the cell wall is weak or damaged, the cell bursts (osmotic lysis).
Hypertonic
Water moves out of the cell, causing its cytoplasm to shrink (plasmolysis).
Cytoplasm
Substance inside plasma membrane but outside the nucleus
Cytosol: fluid portion of cytoplasm
Cytoskeleton: microfilaments, intermediate filaments, microtubles
Cytoplasmic streaming: movement of cytoplasm throughout cells
Nucleoid
Bacterial chromosome (DNA)
Prokaryotic Ribosome
Protein synthesis; 70S (sedimentation)50s/30s subunits
Inclusions
Metachromatic granules(volutin)-phosphate reserves
Polysaccharide granules-energy reserves
Lipid inclusions-energy reserves
Sulfur granules-energy reserves
Carboxysomes-Ribulose 1,5 diphosphate carboxylase for CO2 fixation
Gas vacuoles-protein-covered cylinders
Magnetosomes-iron oxide(destroys H2O2)
Endospores
Resting cells
Resistant to desiccation, heat, chemicals
Bacillus, Clostridium
Sporulation: endospore formation (survival mechanism)
Germination: return to vegetative state (normal ops)
Flagella and Cilia
Microtubules; made of Tubulin a protein; 9 pairs +2 array
Cell wall and glycocalyx
Cell wall are in plants, algae, fungi, carbohydrates
Composed of cellulose, chitin, glucan, mannan
Glycocalyx is made of carbohydrates extending from animal plasma membrane and bonded to proteins and lipids in membrane
Plasma membrane
Phospholipid bilayer
Peripheral proteins
Intergral proteins
Transmembrane proteins
Sterols(eukaryotes have most bacteria don't)
Glycocalyx carbohydrates
Ribosomes
Protein synthesis
80s (eukaryotes); membrane-bound attached to ER; free: in cytoplams
70s in chloroplasts and mitochondria
Organelles
Nucleus: contains chromosomes
ER: transport network
Glogi complex: membrane formation and secretion
Lysosome: digestive enzymes
Vacuole: brings food into cells and provides support
Mitochondrion: cellular respiration(ATP)
Chloraplast: photosynthesis
Peroxisome: oxidation of fatty acids; destroys(H2O2)
Centrosome: consists of protein fibers and centrioles
Endosymbiotic Theory
2 species living together 1 inside of the other