microbiology chapter 3 - york college of pennsylvaniafaculty.ycp.edu/~cmathur/micro ch 3.pdf ·...

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MicrobiologyWith Diseases by Taxonomy

Second Edition

PowerPoint® Lecture Slides

PART A

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings

3Cell Structure and Function


CHAPTER 3

MicrobiologyCell structures and functionsGrowthReproductionResponsivenessMetabolismTable 3-1


Processes of Life

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.1 - Overview

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Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Table 3.5 Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings

Prokaryotes

Do not have membrane surrounding their DNA; no nucleusLack various internal structures bound with phospholipid membranesSmall; ~1.0 µm in diameterSimple structureComprised of bacteria and archaea


Eukaryotes

Have membrane surrounding DNA; have nucleusHave internal membrane-bound organellesAre larger; 10-100 µm in diameterHave more complex structureComprised of algae, protozoa, fungi, animals, and plants


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Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.3 Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings

Cocci

Neisseria gonorrhea Gram negative

S. pneumoniae Gram positiveS. pyogenes

S. aureus Gram positive


bacilli (rods)

Escherichia coli Gram negative

Bacillus cereus Gram positiveB. anthracis


Spiral

Vibrio cholerae Gram negative

Treponema pallidum G –syphilis

Borrelia burgdorferii G-Lyme Disease

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Axial filament


External Structures of Prokaryotic Cells

GlycocalycesFlagellaFimbriae and pili


Glycocalyces

Gelatinous, sticky substance surrounding the outside of the cellComposed of polysaccharides, polypeptides, or bothTwo types

CapsuleSlime layer


Capsule

Composed of organized repeating units of organic chemicalsFirmly attached to cell surfaceProtects cells from drying outMay prevent bacteria from being recognized and destroyed by host

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Slime Layer

Loosely attached to cell surfaceWater solubleProtects cells from drying outSticky layer that allows prokaryotes to attach to surfaces


Flagella

Are responsible for movementHave long structures that extend beyond cell surfaceNot all prokaryotes have flagellaSerotypes: E. coli O157:H7


Flagellar Arrangements

Peritrichous Single polar

Tufted polar


Axial filament

Treponemapallidum

Borreliaburgdorferi

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Bacterial Movement

Figure 3.8

PLAYAnimation:Bacterial Motility

Chemotaxis/phototaxis


Motility http://www.cellsalive.com


Fimbriae and Pili

Nonmotile extensionsFimbriae

Sticky, proteinaceous, bristlelike projectionsUsed by bacteria to adhere to one another, to hosts, and to substances in environmentMay be hundreds per cell and are shorter than flagellaImportant function in biofilms


Pili

Long hollow tubules composed of pilinLonger than fimbriae but shorter than flagellaBacteria typically only have one or two per cellJoin two bacterial cells and mediate the transfer of DNA from one cell to another (conjugation)Also known as conjugation pili or sex pili

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Prokaryotic Cell Wall

Provides structure and shape and protects cell from osmotic forcesAssists some cells in attaching to other cells or in eluding antimicrobial drugsAnimal cells do not have; can target cell wall of bacteria with antibiotics


Prokaryote cell wall


Bacterial Cell Wall

Most have cell wall composed of peptidoglycan; a few lack a cell wall entirelyPeptidoglycan composed of sugars, NAG, and NAMtetrapeptide bridges


Cell walls

G- G +-http://www.ppws.vt.edu/~sforza/prokarote/cell_walls.html

G- G+

Scientists describe two basic types of bacterial cell walls: gram-positive and gram-negative

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G+ cell wall


Gram-Positive Cell Wall

Relatively thick layer of peptidoglycanteichoic acidsRetains crystal violet dye in Gram staining procedure; appear purple


Gram-Negative Cell Walls

Have only a thin layer of peptidoglycanBilayer membrane outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS) May be impediment to the treatment of diseaseFollowing Gram staining procedure, cells appear pink


E. coli O157:H7

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LPS and periplasm

LPS; lipopolysaccharide (union of lipid with sugar)Also known as endotoxinLipid portion known as lipid A

Dead cells release lipid A when cell wall disintegratesMay trigger fever, vasodilation, inflammation, shock, and blood clottingCan be released when antimicrobial drugs kill bacteria

Periplasm located between outer membrane and cell membrane

Contains peptidoglycan and periplasmContains water, nutrients, and substances secreted by the cell, such as digestive enzymes and proteins involved in transport


Bacterial Cell Walls

Figure 3.13b


Cell walls

G- G +-http://www.ppws.vt.edu/~sforza/prokarote/cell_walls.html

G- G+

Scientists describe two basic types of bacterial cell walls: gram-positive and gram-negative


Archael Cell Walls

Do not have peptidoglycanCell walls contain variety of specialized polysaccharides and proteinsGram-positive archaea stain purple Gram-negative archaea stain pink

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Phospholipid Bilayer of CytoplasmicMembrane

Figure 3.14 Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings

Prokaryotic Cytoplasmic Membrane

Referred to as phospholipid bilayer; composed of lipids and associated proteinsApproximately half the membrane is composed of proteins that act as recognition proteins, enzymes, receptors, carriers, or channels

Integral proteins Peripheral proteins Glycoproteins

Fluid mosaic model describes current understanding of membrane structure


Control of Substances Across CytoplasmicMembrane

Naturally impermeable to most substancesProteins allow substances to cross membraneOccurs by passive or active processesMaintains a concentration gradient and electrical gradient

Chemicals concentrated on one side of the membrane or the otherVoltage exists across the membrane


Passive Processes of Transport

DiffusionFacilitated diffusion Osmosis

Isotonic solution Hypertonic solution Hypotonic solution

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Effects of Solutions on Organisms

Figure 3.18 Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings

Cell wall disruption

G+; lysozyme (or penicillin): protoplastG-; lysozyme; spheroplasthttp://www.cellsalive.com


Penicillin discovered


Penicillin Effects

http://http://www.cellsalive.comwww.cellsalive.com

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Active Processes of Transport

Active TransportUtilizes permease proteins and expends ATP

Group TranslocationSubstance chemically modified during transport

PLAYAnimation:Membrane Transport


Nuclear region

One circular chromosome: nucleod

Plasmid: small circular DNA outside of chromosome


Ribosome


Inclusions

Reserve depositsVolutin (Polyphosphates): CorynebacteriumdiphtheriaSulfur granules: ThiobacillusCarboxysomes (enzyme for photosynthesis): Cyanobacteria

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Cytoplasm of Prokaryotes

Cytosol – liquid portion of cytoplasmInclusions – may include reserve deposits of chemicalsRibosomes – sites of protein synthesisCytoskeleton – plays a role in forming the cell’s basic shapeSome bacterial cells produce dormant form called endospore


Endospores

GerminationDormant form; NOT reproductive Resists heating, freezing, desiccation, chemicals and radiationGenera Bacillus and ClostridiumG+ rodsSpore stain


Endospore


Endospore stain

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Eukaryotic cell


External Structure of Eukaryotic Cells

GlycocalycesNever as organized as prokaryotic capsulesHelps anchor animal cells to each otherStrengthens cell surfaceProvides protection against dehydrationFunction in cell-to-cell recognition and communication


Eukaryotic Cell Walls

Fungi, algae, plants, and some protozoa have cell walls but no glycocalyxComposed of various polysaccharides

Cellulose found in plant cell wallsFungal cell walls composed of cellulose, chitin, and/or glucomannanAlgal cell walls composed of cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate, or a combination of these


Eukaryotic Cytoplasmic Membrane

All eukaryotic cells have cytoplasmic membraneIs a fluid mosaic of phospholipids and proteinsContains steroid lipids to help maintain fluidityControls movement into and out of cell

Uses diffusion, facilitated diffusion, osmosis, and active transportPerforms endocytosis; phagocytosis if solid substance and pinocytosis if liquid substanceExocytosis enables substances to be exported from cell

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Endocytosis

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.35


Eukaryotes – outer structures and Nonmembranous Organelles

Flagella: “9 + 2” arrangement of microtubules in all flagellated eukaryotesCiliaRibosomes: Composed of 60S and 40S subunitsCytoskeletonCentrioles and centrosome


Eukaryotic Flagella

Figure 3.27a

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Cytoplasm of Eukaryotes – Membranous Organelles

NucleusEndoplasmic reticulumGolgi bodyLysosomes, peroxisomes, vacuoles, and vesiclesMitochondriaChloroplasts


Endosymbiotic Theory

Eukaryotes formed from union of small aerobic prokaryotes with larger anaerobic prokaryotes; smaller prokaryotes became internal parasites

Parasites lost ability to exist independently; retained portion of DNA, ribosomes, and cytoplasmicmembranesLarger cell became dependent on parasites for aerobic ATP productionAerobic prokaryotes evolved into mitochondriaSimilar scenario for origin of chloroplasts

Not universally accepted

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Table 3.4 Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Table 3.5

microbiology chapter 3 - york college of pennsylvaniafaculty.ycp.edu/~cmathur/micro ch 3.pdf ·...

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