MICRO-s10_07 - 2/10/2010 BIOL 240: General Microbiology...

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Unformatted text preview: 2/10/2010 BIOL 240: General Microbiology General Spring 2010 Rm. 22-116 R, Feb. 11, 2010 http://www.smccd.edu/accounts/staplesn/biol240/ 1. Pre-Lab Writeups: Be sure to prepare before each Lab W riteups Be Monday’s labs (for BOTH Mon. & Wed.)!! Monday – (What? Why? How? are we doing in the lab??) 2. Pre-llecture slides and study guides available on course ecture website by the night before. • (Print WISELY!! If you choose to do so..) 3. Midterm 1 study guides will be updated by this weekend!!! • Review session in LAB ROOM next Thurs. at 12:30pm!!! 1. Describe 4 extracellular structures unique to prokaryotes, and 1. Describe extracellular and explain the function of each. explain REVIEW: REVIEW: TODAY’s Objectives: Students should be able to….. 1. Compare and contrast 5 structural characteristics of the gram Compare positive and gram negative cell walls. Include illustrations. positive 2. Describe the prevailing model of cell membrane structure and how the Describe model and macromolecules that form them exemplify structure determining function. function 3. Compare and contrast the transported molecules, energy balances and Compare membrane molecules required for 2 types each of passive & active transport. transport 4. Compare and contrast 8 differences between “prokaryotic” and Compare and eukaryotic cells. W hat structures do they share in common? eukaryotic What 5. Recognize and describe the properties and functions of the various 5. us Eukaryotic Organelles. Eukaryotic 1 2/10/2010 C. Fimbriae & Pili C. Fimbriae Pili 1. Fimbriae allow allow attachment attachment 2. Pili are used to are transfer DNA from one cell to another one Figure 4.11 D. Cell Wall • Prevents osmotic lysis Prevents lysis • Made of peptidoglycan (in bacteria) Made peptidoglycan Figure 4.6 2 2/10/2010 Peptidoglycan • Polymer of disaccharide – N-acetylglucosamine (NAG) & – N-acetylmuramic acid (NAM) • Linked by polypeptides Figure 4.13a + – Figure 4.13b, c 3 2/10/2010 Gram-positive positive Cell Walls Cell 1. Thick peptidoglycan Thick peptidoglycan 2. Teichoic acids, acids, Lipoteichoic acids Lipoteichoic 3. In acid-fast cells, fast contains mycolic acid mycolic Gram-negative Cell Walls 1. Thin peptidoglycan Thin peptidoglycan 2. No teichoic acids No teichoic 3. Outer membrane – Lipopolysaccharide • Lipid A = endotoxin Lipid endotoxin • O-antigen = polysacc. antigen polysacc 1. Gram-Positive cell walls • Teichoic acids: – Lipoteichoic acid links to plasma membrane – Wall teichoic acid llinks to peptidoglycan inks peptidoglycan Wall teichoic • May regulate movement of cations • Polysaccharides provide antigenic variation Figure 4.13b 4 2/10/2010 2. Gram-Negative Outer Negative Membrane Membrane 1. Lipopolysaccharides, llipoproteins, ipoproteins, phospholipids. phospholipids. 2. Forms the periplasm between the outer Forms periplasm between membrane and the plasma membrane. membrane 3. Protection from phagocytes, complement, Protection antibiotics. antibiotics. a. O polysaccharide antigen, • e.g., E. coli O157:H7. e.g., E. (H = flagellum protein antigen) (H b. Lipid A iis an endotoxin. s endotoxin c. Porins (proteins) form channels through form channels through membrane membrane Gram-Negative Outer Membrane Figure 4.13c 5 2/10/2010 Gram Stain Mechanism Gram Mechanism • Crystal violet-iodine crystals form in cell. • Gram-positive – Alcohol dehydrates peptidoglycan. Alcohol peptidoglycan – CV-I crystals do not leave. • Gram-negative – Alcohol dissolves outer membrane and leaves Alcohol holes (large spaces) in peptidoglycan. peptidoglycan – CV-I washes out. http://student.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/images/gram_stain_11.swf 3. Atypical Cell Walls • Mycoplasmas – Lack cell walls; smallest bacteria! – Sterols iin plasma membrane n • waxy; fatty; hydrophobic; stabilizes from lysis? waxy; lysis • Archaea – Wall-less, or Gram -, S-layer of woven surface proteins Gram – W alls of pseudomurein Walls pseudomurein – N-acetylalosaminuronic acid http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=73 Pseudomurein Gram +, +/- S-layer • (lack NAM and D amino acids) • NAT = 6 2/10/2010 4. Damage to Cell Walls 4. 1. Lysozyme digests disaccharide (NAMNAG) in peptidoglycan. NAG) peptidoglycan 2. Penicillin iinhibits peptide bridge formation nhibits in peptidoglycan, & activates “autolysins”. peptidoglycan activates 3. Protoplast is a wall-less cell. 4. Spheroplast iis a ‘wall-less’ Gram-negative s cell. 5. L forms are wall-lless cells that swell into ess irregular shapes. irregular – Protoplasts and spheroplasts are susceptible to Protoplasts spheroplasts are osmotic lysis. l ysis E. Plasma Membrane 1. Phospholipid bilayer 1. Phospholipid bilayer 2. Peripheral proteins 3. Integral proteins 4. Transmembrane proteins Figure 4.14 7 2/10/2010 * Fluid Mosaic Model * Fluid • Membrane is as viscous as olive oil. • Proteins move to function. • Phospholipids rotate and move laterally. • “Proteins afloat Proteins in a sea of phospholipids” phospholipids Figure 4.14b Prok. Plasma Membrane • Selective permeability allows passage of Selective some molecules some • Enzymes for ATP production • Photosynthetic pigments on foldings called Photosynthetic foldings called chromatophores or thylakoids chromatophores or thylakoids Figure 4.15 8 2/10/2010 Plasma Membrane • Damage to the membrane by by – alcohols, – quaternary ammonium (detergents) and (detergents) • Preservatives – polymyxin antibiotics • Causes leakage of cell contents. • Polymyxin B, Polymyxin E (colistin): B, Polymyxin • Drugs compete with divalent cations (Mg++, Ca++) – destabilize lipid bilayers. destabilize bilayers F. Movement Across Membranes Membranes 1.PASSIVE TRANSPORT: PASSIVE a) Simple diffusion: Movement of a solute Movement from an area of high concentration to an area of low conc’n. conc b) Facilitated diffusion: Solute combines with Solute a transporter protein in the membrane. in Figure 4.17 9 2/10/2010 Movement Across Membranes • Osmosis: Movement of water across a selectively permeable membrane selectively – from an area of high [H2O] to an area of from high to lower [H2O]. lower • Osmotic pressure: The pressure needed to Osmotic stop the movement of water across the membrane. stop Figure 4.18ab ISO- = same same HYPO- = low HYPO HYPER- = high Figure 4.18c-e 10 2/10/2010 Movement Across Membranes 2. Active transport of substances of requires a transporter protein and ATP. requires 3. Group translocation of substances of requires a transporter protein and PEP. requires – Unique to prokaryotes – PEP phosphorylates sugar after enters PEP phosphorylates sugar cytoplasm; sugars trapped and concentrated! cytoplasm; 4. Bulk Transport in Euk: Endocytosis, Bulk Euk Endocytosis Exocytosis Exocytosis – Phagocytosis & Pinocytosis Pinocytosis G. Cytoplasm H. Nuclear Area • “Nucleoid” = DNA DNA • Cytoplasm is the Cytoplasm substance inside the and associated proteins (chromosome) plasma membrane plasma Capsule Cell wall PM Figure 4.6 11 2/10/2010 i. Ribosomes i. Ribosomes • “Protein Factories” Figure 4.19 J. Inclusions Metachromatic granules (volutin) Polysaccharide Polysaccharide granules granules Lipid inclusions Sulfur granules Carboxysomes Gas vacuoles Magnetosomes Phosphate reserves Energy reserves Energy reserves Energy reserves Ribulose 1,5-diphosphate carboxylase diphosphate carboxylase for CO2 fixation (photosynthesis!) Protein covered cylinders -- buoyancy Protein -Iron oxide (destroys H2O2) 12 2/10/2010 K. Endospores K. Endospores • Resting cells • Resistant to desiccation, heat, chemicals – Dipicolinic acid + Calcium • Bacillus, Clostridium • Sporulation: Endospore formation Endospore • Germination: Return to vegetative state Figure 4.21 13 2/10/2010 4.2) Eukaryotic Cells • Comparing Prokaryotic & Eukaryotic Cells – Prokaryote comes from the Greek words for Prokaryote pre-nucleus. pre – Eukaryote comes from the Greek words for Eukaryote true nucleus. true Plant Figure 4.22 Alga Plasma Plasma B-Cell Animal Prokaryotic vs. Eukaryotic Cells vs. Eukaryotic 1. No true nucleus 2. No memb.-bound No memb bound organelles organelles 3. Single, circular chromosome Single, chromosome 4. 70S ribosomes 70S ribosomes 5. Unique cell wall (PG) 6. Unique flagella 7. Outer Membrane (gram -) Outer 8. Only unicellular 9. Small (1-5 m diameter) 1. True Nucleus 2. Memb.-bound nucleus and bound other organelles 3. Many, linear chromosomes 3. 4. 80S ribosomes 80S ribosomes 5. Plants and Fungi CW ’s Plants CW 6. Microtubule flagella 7. No O.M. 8. Many spp. Multicellular Many Multicellular 9. Larger (10-100 m diameter) 100 14 2/10/2010 A. Flagella and Cilia Figure 4.23 • Microtubules + motor proteins – Tubulin • 9 pairs + 2 -- arrangements pairs -- B. Euk. Cell Wall B. Euk • Cell wall – Plants, algae, fungi – Carbohydrates • Cellulose, chitin, glucan, Cellulose, glucan mannan, pectins mannan pectins • Glycocalyx jjejunum, glycocalyx and enteroendocrine cell ejunum, glycocalyx and enteroendocrine cell – Carbohydrates extending from animal plasma Carbohydrates membrane membrane – Bonded to proteins and lipids in membrane 15 2/10/2010 C. Euk. Plasma Membrane C. Euk 1. Phospholipid bilayer 2. Peripheral proteins 3. Integral proteins 4. Transmembrane proteins 5. Sterols (animal cells, [mycoplasmas]],, Sterols (animal fungi, plants) fungi, 6. Glycocalyx carbohydrates Euk. Plasma Membrane • Selective permeability allows passage of Selective some molecules some 1. 2. 3. 4. 5. Simple diffusion Facilitated diffusion Osmosis Active transport Endocytosis • Phagocytosis: Pseudopods extend and engulf Pseudopods extend particles particles • Pinocytosis: Membrane folds inward bringing in Membrane fluid and dissolved substances fluid 16 2/10/2010 Eukaryotic Cell Cytoplasm Substance inside plasma membrane Substance & outside nucleus outside Cytosol Fluid portion of cytoplasm Cytoskeleton Microfilaments, intermediate Microfilaments, filaments, microtubules filaments, Cytoplasmic Movement of cytoplasm throughout Movement streaming cells cells Figure 4.22b D. Eukaryotic Organelles: NOT membrane-Bound 1. Ribosome = Protein synthesis 2. Centrosome = Consists of protein fibers Consists and centrioles centrioles 3. Centriole = Mitotic spindle formation Figure 4.22a 17 2/10/2010 E. Eukaryotic Organelles: Membrane-Bound 1. Nucleus = Contains chromosomes. 2. ER = Synthesis & transport network. 3. Golgi complex = Membrane Membrane formation and secretion. formation 4. Lysosome = Digestive enzymes 5. Vacuole = Brings food into cells and Vacuole provides support. provides 6. Mitochondrion = Cellular respiration Mitochondrion Cellular 7. Chloroplast = Photosynthesis 8. Peroxisome = Oxidation of fatty Oxidation acids; destroys H2O2. acids; (E.) Memb. Bound Organelles: (E.) Memb 1. Nucleus **** 1. Nucleus 1. Nuclear Pores 2. Chromatin – Complex of DNA Complex and protein and – Histones; nonhistones nonhistones 3. Nucleolus – Site of Ribosome Site synthesis synthesis Figure 4.24 18 ...
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