Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture...

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation prepared by Christine L. Case

Microbiology

B.E Pruitt & Jane J. Stein

AN INTRODUCTIONEIGHTH EDITION

TORTORA • FUNKE • CASE

Functional Anatomy of Prokaryotic and Eukaryotic Cells


Size Comparisons of Selected Microorganisms/Parasites


Prions and Viroids

• Prions are proteins that are believed to cause diseases like BSE.

• Viroids are small RNA’s with no associated protein that causes diseases in plants.

• Neither fit the criteria for living organisms, but they are microbes and are therefore studied by microbiologists.


Viruses

• Consist of nucleic acid and protein.


Viruses 2

• Obligate intracellular parasites.


Viruses 3

• Are they really alive?

• In general, are smaller than most prokaryotes.


Viruses 4

• Reproduce using host cell mechanisms.


Viruses 4

• Adenovirus

Copyright notice: This notice must accompany any copy of the images. The images must not be used for commercial purposes without the consent of the copyright owners. The images are not in the public domain. The images can be freely used for educational purposes.

Copyright 1994 Veterinary Sciences Division.

• Rhinovirus


Prokaryotic Cells

• Comparing Prokaryotic and Eukaryotic Cells

• Prokaryote comes from the Greek words for prenucleus.

• Eukaryote comes from the Greek words for true nucleus.


• 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


• Average size: 0.2 -1.0 µm 2 - 8 µm

• Basic shapes:


• Unusual shapes

• Star-shaped Stella

• Square Haloarcula

• Most bacteria are monomorphic

• A few are pleomorphic

Figure 4.5


• Pairs: diplococci, diplobacilli

• Clusters: staphylococci

• Chains: streptococci, streptobacilli

Arrangements


• 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


• 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


Flagella Arrangement

Figure 4.7


• 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


Motile Cells

Figure 4.9


• Endoflagella

• In spirochetes

• Anchored at one end of a cell

• Rotation causes cell to move

Axial Filaments

Figure 4.10a


• Fimbriae allow attachment

• Pili are used to transfer DNA from one cell to another

Figure 4.11


Pili

• Short protein appendages

• smaller than flagella

• Adhere bacteria to surfaces

• E. coli has numerous types

• K88, K99, F41, etc.

• Antibodies to will block adherance

• F-pilus; used in conjugation

• Exchange of genetic information

• Flotation; increase boyancy

• Pellicle (scum on water)

• More oxygen on surface


F-Pilus for Conjugation


• Prevents osmotic lysis

• Made of peptidoglycan (in bacteria)

Cell Wall

Figure 4.6a, b


• Polymer of disaccharideN-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM)

• Linked by polypeptides

Peptidoglycan

Figure 4.13a


• 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


Teichoic Acids

• Gram + only

• Glycerol, Phosphates, & Ribitol

• Attachment for Phages


• 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


• 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


Gram-Negative Outer Membrane

Figure 4.13c


Lipopolysaccharide (LPS)• Endotoxin or Pyrogen

• Fever causing

• Toxin nomenclature

• Endo- part of bacteria

• Exo- excreted into environment

• Structure

• Lipid A

• Polysaccharide

• O Antigen of E. coli, Salmonella

• G- bacteria only

• Alcohol/Acetone removes


LPS (cont’d)

• Functions

• Toxic; kills mice, pigs, humans

• G- septicemia; death due to LPS

• Pyrogen; causes fever

• DPT vaccination always causes fevers

• Adjuvant; stimulates immunity

• Heat Resistant; hard to remove

• Detection (all topical & IV products)

• Rabbits (measure fever)

• Amoebocytes Lyse in presence of LPS


LPS (cont’d.)

• Appearance of Colonies

• Mucoid = Smooth (lots of LPS or capsule)

• Dry = Rough (little LPS or capsule)

• O Antigen of Salmonella and E. coli

• 2,000 different O Ags of Salmonella

• 100’s different O Ags of E. coli

• E. coli O157

• O Ags differ in Sugars, not Lipid A


• 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


• 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


Bacterial Stains


Plasma Membrane

Figure 4.14a


Plasma Membrane

• Phospholipid bilayer

• Peripheral proteins

• Integral proteins

• Transmembrane proteins

Figure 4.14b


• Membrane is as viscous as olive oil.

• Proteins move to function

• Phospholipids rotate and move laterally

Fluid Mosaic Model

Figure 4.14b


Cytoplasm

• 80% Water {20% Salts-Proteins)

• Osmotic Shock important

• DNA is circular, Haploid

• Advantages of 1N DNA over 2N DNA

• More efficient; grows quicker

• Mutations allow adaptation to environment quicker

• Plasmids; extra circular DNA

• Antibiotic Resistance

• No organelles (Mitochondria, Golgi, etc.)


Spores

SPORE


Cross-section of Bacillus spore

The central protoplast, or germ cell, carries the constituents of the future vegetative cell, accompanied by dipicolinic acid --heat resistance of the spore.

Surrounding the protoplast is a cortex consisting largely of peptidoglycan (murein), -- heat and radiation resistance of the spore.

The inner layer, the cortical membrane or protoplast wall, becomes the cell wall of the new vegetative cell when the spore germinates.

The spore coats, which constitute up to 50 percent of the volume of the spore, protect it from chemicals, enzymes, etc.


The developmental cycle of the Endospore.


Bacterial endospores. Phase microscopy of sporulating bacteria demonstrates the refractility of endospores, as well as characteristic spore shapes and locations within the mother cell.


• Mycoplasmas

• Lack cell walls

• Sterols in plasma membrane

• Archaea

• Wall-less, or

• Walls of pseudomurein (lack NAM and D amino acids)

Atypical Cell Walls


Archaebacteria

• Newly added taxonomic kingdom.


Archeabacteria 2

• Single celled prokaryotes.

• Extremophiles.

• 4 broad groups.

• Methanogens + extreme halophiles

• Methanogens only

• Sulfur dependent

• Thermophiles


Archeabacteria 3

The preceding Methanobacterim image is from the Department of Microbiology and Evolutionary Biology at the University of Nijmegen, the Netherlands.

http://www-micrbiol.sci.kun.nl/micrbiol/micrgala.html


Eukaryote Cell Structure


Algae

• Eukaryotes that may be unicellular, colonial or filamentous.

These images are from the Molecular Evolution and Organelle Genomics program at the University of Montreal. Copyright 1994-1997 by Charles J. O’Kelly and Tim Littlejohn. Distribution for noncommercial purposes permitted so long as this copyright notice is included and acknowledgement is made.


Algae 2

• Aquatic or terrestrial.

• Mostly plant-like characteristics.

• Photosynthetic.

• Great variety of types, but all contain chlorophyll.

• Some animal-like characteristics like phagocitosis of other organisms.


Algae 3

• Important marine food source.


Protozoa• Single celled eukaryotes, but may form

colonial aggregates.

• Aquatic with animal-like characteristics.

This image is from the Molecular Evolution and Organelle Genomics program at the University of Montreal. Copyright 1994-1997 by Charles J. O’Kelly and Tim Littlejohn. Distribution for noncommercial purposes permitted so long as this

copyright notice is included and acknowledgement is made.


Protozoa 2

• Ingest organic matter for nutrients.

• Vary greatly in size from 0.003mm to 5mm.

• Many are human parasites.

• Most are motile.


Fungi• Very diverse group of eukaryotes.

• Not all are microbes.

• Yeasts are unicellular and spherical.

• Molds are filamentous with branching.

The preceding Pyromyces sp. image is from the Department of Microbiology

and Evolutionary Biology at the University of Nijmegen, the Netherlands. http://wwwmicrbiol.sci.kun.nl/micrbiol/micrgala.html


Fungi 2

• Non-photosynthetic.

• Require the uptake of organic matter for nutrients.

• Saprophytic or parasitic.

• Propagate by spores.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture...

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