2008 Functional Anatomy of Prokaryotic and Eukaryotic Cells.
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Transcript of 2008 Functional Anatomy of Prokaryotic and Eukaryotic Cells.
2008
• Functional Anatomy of Prokaryotic and Eukaryotic Cells
2008
Prokaryotic Cells
• Comparing Prokaryotic and Eukaryotic Cells
• Prokaryote comes from the Greek words for prenucleus.
• Eukaryote comes from the Greek words for true nucleus.
2008
• One circular chromosome, not in a membrane
• No histones
• No organelles
• Peptidoglycan cell walls
• Binary fission
Prokaryote Eukaryote
• Paired chromosomes, in nuclear membrane
• Histones
• Organelles
• Polysaccharide cell walls
• Mitotic spindle
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• Average size: 0.2 -1.0 µm 2 - 8 µm
• Basic shapes:
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• Unusual shapes
• Star-shaped Stella
• Square Haloarcula
• Most bacteria are monomorphic
• A few are pleomorphic
Figure 4.5
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• Pairs: diplococci, diplobacilli
• Clusters: staphylococci
• Chains: streptococci, streptobacilli
Arrangements
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• Outside cell wall
• Usually sticky
• A capsule is neatly organized
• A slime layer is unorganized & loose
• Extracellular polysaccharide allows cell to attach
• Capsules prevent phagocytosis
Glycocalyx
Figure 4.6a, b
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• Outside cell wall
• Made of chains of flagellin
• Attached to a protein hook
• Anchored to the wall and membrane by the basal body
Flagella
Figure 4.8
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Flagella Arrangement
Figure 4.7
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Flagella arrangement flash animation
2008Figure 4.8
2008
Flagella structure flash animation
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• Rotate flagella to run or tumble
• Move toward or away from stimuli (taxis)
• Flagella proteins are H antigens (e.g., E. coli O157:H7)
Motile Cells
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Motile Cells
Figure 4.9
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• Endoflagella
• In spirochetes
• Anchored at one end of a cell
• Rotation causes cell to move
Axial Filaments
Figure 4.10a
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Motility flash animation
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• Fimbriae allow attachment
• Pili are used to transfer DNA from one cell to another
Figure 4.11
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• Prevents osmotic lysis
• Made of peptidoglycan (in bacteria)
Cell Wall
Figure 4.6a, b
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• Polymer of disaccharideN-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM)
• Linked by polypeptides
Peptidoglycan
Figure 4.13a
2008Figure 4.13b, c
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• Thick peptidoglycan
• Teichoic acids
• In acid-fast cells, contains mycolic acid
Gram-positive cell walls Gram-negative cell walls
• Thin peptidoglycan
• No teichoic acids
• Outer membrane
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• Teichoic acids:
• Lipoteichoic acid links to plasma membrane
• Wall teichoic acid links to peptidoglycan
• May regulate movement of cations
• Polysaccharides provide antigenic variation
Gram-Positive cell walls
Figure 4.13b
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• Lipopolysaccharides, lipoproteins, phospholipids.
• Forms the periplasm between the outer membrane and the plasma membrane.
• Protection from phagocytes, complement, antibiotics.
• O polysaccharide antigen, e.g., E. coli O157:H7.
• Lipid A is an endotoxin.
• Porins (proteins) form channels through membrane
Gram-Negative Outer Membrane
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Gram-Negative Outer Membrane
Figure 4.13c
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• Crystal violet-iodine crystals form in cell
• Gram-positive
• Alcohol dehydrates peptidoglycan
• CV-I crystals do not leave
• Gram-negative
• Alcohol dissolves outer membrane and leaves holes in peptidoglycan
• CV-I washes out
Gram Stain Mechanism
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• Mycoplasmas
• Lack cell walls
• Sterols in plasma membrane
• Archaea
• Wall-less, or
• Walls of pseudomurein (lack NAM and D amino acids)
Atypical Cell Walls
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• Lysozyme digests disaccharide in peptidoglycan.
• Penicillin inhibits peptide bridges in peptidoglycan.
• Protoplast is a wall-less cell.
• Spheroplast is a wall-less Gram-positive cell.
• L forms are wall-less cells that swell into irregular shapes.
• Protoplasts and spheroplasts are susceptible to osmotic lysis.
Damage to Cell Walls
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Plasma Membrane
Figure 4.14a
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Plasma Membrane
• Phospholipid bilayer
• Peripheral proteins
• Integral proteins
• Transmembrane proteins
Figure 4.14b
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• Membrane is as viscous as olive oil.
• Proteins move to function
• Phospholipids rotate and move laterally
Fluid Mosaic Model
Figure 4.14b
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• Selective permeability allows passage of some molecules
• Enzymes for ATP production
• Photosynthetic pigments on foldings called chromatophores or thylakoids
Plasma Membrane
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• Damage to the membrane by alcohols, quaternary ammonium (detergents) and polymyxin antibiotics causes leakage of cell contents.
Plasma Membrane
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• Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentration.
• Facilitative diffusion: Solute combines with a transporter protein in the membrane.
Movement Across Membranes
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Movement Across Membranes
Figure 4.17
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• Osmosis
• Movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water.
• Osmotic pressure
• The pressure needed to stop the movement of water across the membrane.
Movement Across Membranes
Figure 4.18a
2008Figure 4.18c-e
2008
• Active transport of substances requires a transporter protein and ATP.
• Group translocation of substances requires a transporter protein and PEP.
Movement Across Membranes
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• Cytoplasm is the substance inside the plasma membrane
Cytoplasm
Figure 4.6a, b
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• Nuclear area (nucleoid)
Nuclear Area
Figure 4.6a, b
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Ribosomes
Figure 4.6a
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Ribosomes
Figure 4.19
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• Metachromatic granules (volutin)
• Polysaccharide granules
• Lipid inclusions
• Sulfur granules
• Carboxysomes
• Gas vacuoles
• Magnetosomes
Inclusions
•Phosphate reserves
•Energy reserves
•Energy reserves
•Energy reserves
•Ribulose 1,5-diphosphate carboxylase for CO2 fixation
•Protein covered cylinders
•Iron oxide (destroys H2O2)
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• Resting cells
• Resistant to desiccation, heat, chemicals
• Bacillus, Clostridium
• Sporulation: Endospore formation
• Germination: Return to vegetative state
Endospores
2008Figure 4.21a
2008
Eukaryotic Cells
• Comparing Prokaryotic and Eukaryotic Cells
• Prokaryote comes from the Greek words for prenucleus.
• Eukaryote comes from the Greek words for true nucleus.
2008Figure 4.22a
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Flagella and Cilia
Figure 4.23a, b
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• Microtubules
• Tubulin
• 9 pairs + 2 arrangements
Figure 4.23c
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• Cell wall
• Plants, algae, fungi
• Carbohydrates
• Cellulose, chitin, glucan, mannan
• Glycocalyx
• Carbohydrates extending from animal plasma membrane
• Bonded to proteins and lipids in membrane
Cell Wall
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• Phospholipid bilayer
• Peripheral proteins
• Integral proteins
• Transmembrane proteins
• Sterols
• Glycocalyx carbohydrates
Plasma Membrane
2008
• Selective permeability allows passage of some molecules
• Simple diffusion
• Facilitative diffusion
• Osmosis
• Active transport
• Endocytosis
• Phagocytosis: Pseudopods extend and engulf particles
• Pinocytosis: Membrane folds inward bringing in fluid and dissolved substances
Plasma Membrane
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• Cytoplasm Substance inside plasma membrane and outside nucleus
• Cytosol Fluid portion of cytoplasm
• Cytoskeleton Microfilaments, intermediate
filaments, microtubules
• Cytoplasmic streaming Movement of cytoplasm throughout cells
Eukaryotic Cell
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• Membrane-bound:
• Nucleus Contains chromosomes
• ER Transport network
• Golgi complex Membrane formation and secretion
• Lysosome Digestive enzymes
• Vacuole Brings food into cells and provides support
• Mitochondrion Cellular respiration
• Chloroplast Photosynthesis
• Peroxisome Oxidation of fatty acids; destroys H2O2
Organelles
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• Not membrane-bound:
• Ribosome Protein synthesis
• Centrosome Consists of protein fibers and centrioles
• Centriole Mitotic spindle formation
Eukaryotic Cell
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Nucleus
Figure 4.24
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Endoplasmic Reticulum
Figure 4.25
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• 80S
• Membrane-bound Attached to ER
• Free In cytoplasm
• 70S
• In chloroplasts and mitochondria
Ribosomes
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Golgi Complex
Figure 4.26
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Lysosomes
Figure 4.22b
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Vacuoles
Figure 4.22b
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Mitochondrion
Figure 4.27
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Chloroplast
Figure 4.28
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Endosymbiotic Theory
Figure 10.2