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Unformatted text preview: 2/8/2010 BIOL 240: General Microbiology General
Spring 2010 Rm. 22-116 T, Feb. 9, 2010
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!!! 1. List the 4 types of macromolecules iin living systems, and describe how n 1. List types the components of each particular molecular structure determines its biological function. …… biological …… REVIEW: REVIEW: TODAY’s Objectives: Students should be able to….. 1. Describe 4 extracellular structures unique to Describe prokaryotes, and explain the function of each. prokaryotes 2. Compare and contrast 5 structural characteristics of the Compare gram positive and gram negative cell walls. Include gram Include illustrations. illustrations. 3. Describe the prevailing model of cell membrane structure Describe model and how the macromolecules that form them exemplify and structure determining function. structure 4. Compare and contrast 8 differences between “prokaryotic” Compare and eukaryotic cells. W hat structures do they share in What common? ………. ……… 1 2/8/2010 a.) DNA
• Has deoxyribose Has deoxyribose • Exists as a double Exists helix helix • A hydrogen bonds hydrogen with T • C hydrogen bonds hydrogen with G
Figure 2.16 b.) RNA
• • • Has ribose Has ribose Is single-stranded A hydrogen bonds hydrogen with U • C hydrogen bonds hydrogen with G Figure 2.17 2 2/8/2010 c.) ATP
• Has ribose, adenine, and Has 3 phosphate groups phosphate X -X X
X X X Figure 2.18 ATP
• Is made by dehydration synthesis. Is dehydration
– Absorbs/requires energy = Endergonic Absorbs/requires Endergonic • Is broken by hydrolysis to liberate useful Is hydrolysis to energy for the cell. energy
– Releases energy = Exergonic Releases Exergonic 3 2/8/2010 Chapter 4
Functional Anatomy of Functional Prokaryotic & Eukaryotic Cells Cells 4.1) Prokaryotic Cells 4.1) Prokaryotic
• Average size: 0.2 -1.0 µm 2 - 8 µm Average 1.0 • Basic shapes: 4 2/8/2010 • Unusual shapes
– Star-shaped Stella shaped Stella – Square Haloarcula Square Haloarcula • Most bacteria are Most monomorphic monomorphic (one shape) • A few are few pleiomorphic pleiomorphic (many forms/shapes)
Figure 4.5 Arrangements
• Pairs: diplococci, diplococci diplobacilli diplobacilli • Clusters: staphylococci • Chains: streptococci, streptococci, streptobacilli streptobacilli 5 2/8/2010 A. Glycocalyx A. Glycocalyx Figure 4.6 • • • • Outside cell wall Usually sticky A capsule is neatly organized capsule A slime layer is unorganized & loose slime
– Extracellular polysaccharide (EPS) allows cell to attach Extracellular allows – Capsules prevent phagocytosis Capsules phagocytosis • Outside cell wall • Made of chains of flagellin Made flagellin • Attached to a protein hook Attached hook • Anchored to the wall and membrane by the basal body Anchored basal B. Flagella Figure 4.8 6 2/8/2010 Flagella Arrangement Figure 4.7 Motile Cells
• Rotate flagella to run or tumble Rotate run or tumble • Move toward or away from stimuli (taxis) • Flagella proteins are H antigens are antigens
– e.g., E. coli O157:H7 e.g., E.
CW CCW CW CCW Figure 4.9 7 2/8/2010 B2. Flagella: Axial Filaments Flagella: Axial
• • • • Endoflagella In spirochetes In spirochetes Anchored at one end of a cell Rotation causes cell to move
http://www.cytoviva.com/g allery_flash.htm - Borrelia Figure 4.10 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 8 2/8/2010 D. Cell Wall
• Prevents osmotic lysis Prevents lysis • Made of peptidoglycan (in bacteria) Made peptidoglycan Figure 4.6 Peptidoglycan
• Polymer of disaccharide
– N-acetylglucosamine (NAG) & – N-acetylmuramic acid (NAM) • Linked by polypeptides Figure 4.13a 9 2/8/2010 + –
Figure 4.13b, c 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
• Lipid A = endotoxin Lipid endotoxin • O-antigen = polysacc. antigen polysacc 10 2/8/2010 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 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 11 2/8/2010 Gram-Negative Outer Membrane Figure 4.13c 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 12 2/8/2010 3. Atypical Cell Walls
– Lack cell walls; smallest bacteria! – Sterols iin plasma membrane n
• waxy; fatty; hydrophobic; stabilizes from lysis? waxy; lysis
Gram -, S-layer Gram • Archaea
– Wall-less, or – W alls of pseudomurein Walls pseudomurein
• (lack NAM and D amino acids) • NAT =
– N-acetylalosaminuronic acid
Gram -, +/- S- layer Gram 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 13 2/8/2010 E. Plasma Membrane 1. Phospholipid bilayer
1. Phospholipid bilayer 2. Peripheral proteins 3. Integral proteins 4. Transmembrane proteins Figure 4.14 * 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 14 2/8/2010 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 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 15 2/8/2010 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 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 16 ...
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This note was uploaded on 03/18/2010 for the course BIOL 240 taught by Professor Staples during the Spring '09 term at Canada College.
- Spring '09