Talaro's Foundations in Microbiology Chapter 4 PDF

Because learning changes everything. ® Chapter 4 A Survey of Prokaryotic Cells and Microorganisms Talaro’s Foundations in Microbiology Twelfth Edition Barry Chess © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written c...

Because learning changes everything. ® Chapter 4 A Survey of Prokaryotic Cells and Microorganisms Talaro’s Foundations in Microbiology Twelfth Edition Barry Chess © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Characteristics of Cells and Life All living things (single and multicellular) are made of cells that share some common characteristics: Basic shape – spherical, cubical, cylindrical Internal content – cytoplasm, surrounded by a membrane DNA chromosome(s), ribosomes, metabolic capabilities Two basic cell types: eukaryotic and prokaryotic © McGraw Hill LLC. 2  Characteristics of Cells 1 Eukaryotic cells: animals, plants, fungi, and protists Contain membrane-bound organelles that compartmentalize the cytoplasm and perform specific functions Contain double-membrane bound nucleus with DNA chromosomes Prokaryotic cells: bacteria and archaea No nucleus or other membrane-bound organelles © McGraw Hill LLC. 3  Characteristics of Cells 2 Access the text alternative for slide images. © McGraw Hill LLC. 4  Characteristics of Life Reproduction and heredity – genome composed of DNA packed in chromosomes; produce offspring sexually or asexually Growth and development Metabolism – chemical and physical life processes Movement and/or irritability – respond to internal/external stimuli; self-propulsion of many organisms Cell support, protection, and storage mechanisms – cell walls, vacuoles, granules and inclusions Transport of nutrients and waste © McGraw Hill LLC. 5  Structure of a Bacterial Cell Access the text alternative for slide images. © McGraw Hill LLC. 6  External Structures Appendages Two major groups of appendages: Motility – flagella and axial filaments (periplasmic flagella) Attachment or channels – fimbriae and pili Glycocalyx – surface coating © McGraw Hill LLC. 7  Flagella 1 3 parts: Filament – long, thin, helical structure composed of protein flagellin Hook – curved sheath Basal body – stack of rings firmly anchored in cell wall © McGraw Hill LLC. 8  Flagella 2 Access the text alternative for slide images. © McGraw Hill LLC. 9  Flagella 3 Rotates 360° Functions in motility of cell through environment Access the text alternative for slide images. © McGraw Hill LLC. 10  Flagellar Arrangements 1 Monotrichous – single flagellum at one end Lophotrichous – small bunches emerging from the same site Amphitrichous – flagella at both ends of cell Peritrichous – flagella dispersed over surface of cell © McGraw Hill LLC. 11  Flagellar Arrangements 2 (a): Source: Louisa Howard/Dartmouth Electron Microscope Facility; © McGraw Hill LLC. 12  Flagellar Arrangements 3 (b): Heather Davies/Science Source © McGraw Hill LLC. 13  Flagellar Arrangements 4 (c): From: W.J. Strength and N.R. Krieg”, “Flagellar activity in an aquatic bacterium”, “Can. J. Microbiol. May 1971, 17:1133-1137, Fig. 5. Reproduced by permission of the National Research Council of Canada”; © McGraw Hill LLC. 14  Flagellar Arrangements 5 (d): PTP/Phototake © McGraw Hill LLC. 15  Flagellar Responses 1 Guide bacteria in a direction in response to external stimulus: Chemical stimuli – chemotaxis; positive and negative Light stimuli – phototaxis Signal sets flagella into motion clockwise or counterclockwise: Counterclockwise – results in smooth linear direction – run Clockwise – tumbles © McGraw Hill LLC. 16  Flagellar Responses 2 Key Access the text alternative for slide images. © McGraw Hill LLC. 17  Flagellar Responses 3 a) No attractant or repellent Access the text alternative for slide images. © McGraw Hill LLC. 18  Flagellar Responses 4 b) Gradient of attractant concentration Access the text alternative for slide images. © McGraw Hill LLC. 19  Periplasmic Flagella 1 Internal flagella, enclosed in the space between the outer sheath and the cell wall peptidoglycan Produce cellular motility by contracting and imparting twisting or flexing motion © McGraw Hill LLC. 20  Periplasmic Flagella 2 (a): Courtesy of Dr. Misha Kudryashev and Dr. Friedrich Frischknecht, Mol Microbiol, 2009 Mar; 71(6):1415-34. Access the text alternative for slide images. © McGraw Hill LLC. 21  Concept Check: (1) Which of the following best describes the action of the prokaryotic flagellum? A. It whips back and forth to move the cell B. It extends and contracts to move the cell C. It rotates to move the cell D. It attaches to the environment and pulls the cell E. It is capable of all of the above © McGraw Hill LLC. 22  Concept Check: (2) Which of the following best describes the action of the prokaryotic flagellum? A. It whips back and forth to move the cell B. It extends and contracts to move the cell C. It rotates to move the cell D. It attaches to the environment and pulls the cell E. It is capable of all of the above Answer: E © McGraw Hill LLC. 23  Fimbriae 1 Fine, proteinaceous, hairlike bristles emerging from the cell surface Function in adhesion to other cells and surfaces © McGraw Hill LLC. 24  Fimbriae 2 Eye of Science/Science Source © McGraw Hill LLC. 25  Pili 1 Flexible tubular structure made of pilin protein Found only in gram-negative cells Function to join bacterial cells for partial DNA transfer called conjugation © McGraw Hill LLC. 26  Pili 2 L. Caro/SPL/Science Source © McGraw Hill LLC. 27  Glycocalyx 1 Coating of molecules external to the cell wall, made of sugars and/or proteins Two types: Slime layer - loosely organized and attached Capsule - highly organized, tightly attached © McGraw Hill LLC. 28  Glycocalyx 2 Access the text alternative for slide images. © McGraw Hill LLC. 29  Functions of the Glycocalyx 1 Protect cells from dehydration and nutrient loss Inhibit killing by white blood cells by phagocytosis, contributing to pathogenicity Attachment - formation of biofilms © McGraw Hill LLC. 30  Functions of the Glycocalyx 2 (a): Barry Chess Access the text alternative for slide images. © McGraw Hill LLC. 31  Functions of the Glycocalyx 3 b): Steven P. Lynch Access the text alternative for slide images. © McGraw Hill LLC. 32  The Cell Envelope External covering outside the cytoplasm Composed of two basic layers: Cell wall and cell membrane Maintains cell integrity Two different groups of bacteria demonstrated by Gram stain: Gram-positive bacteria: thick cell wall composed primarily of peptidoglycan and cell membrane Gram-negative bacteria: outer cell membrane, thin peptidoglycan layer, and cell membrane © McGraw Hill LLC. 33  Structure of Cell Walls 1 Determines cell shape, prevents lysis due to changing osmotic pressures Peptidoglycan is the primary component: Unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments © McGraw Hill LLC. 34  Structure of Cell Walls 2 The figure of the “Structure of Cell Walls.” a) The peptidoglycan of a cell wall is a huge, three- dimensional latticework that is actually one giant molecule which surrounds and support the cell. b) The molecular pattern of peptidoglycan consists of alternating glycans (NAG and NAM) bound together in long strands. The NAG stands for N-acetyl glucosamine, and the NAM stands for N-acetyl muramic acid. Adjacent muramic acid molecules on parallel chains are bound by a cross-linkage of peptides (brown spheres). © McGraw Hill LLC. 35  Structure of Cell Walls 3 The figure of the “Structure of Cell Walls” continues on this slide. c) An enlarged view of the links between the NAM molecules. Tetrapeptide chains branching off the muramic acids connect by amino acid interbridges. The amino acids in the interbridge can vary or may be lacking entirely. It is this linkage that provides rigid yet flexible support to the cell. © McGraw Hill LLC. 36  Structure of Cell Walls 4 The figure of the “Structure of Cell Walls” continues on this slide. Access the text alternative for slide images. © McGraw Hill LLC. 37  Gram-Positive Cell Wall 1 20 to 80 nm thick peptidoglycan Includes teichoic acid and lipoteichoic acid: function in cell wall maintenance and enlargement during cell division; stimulate a specific immune response Some cells have a periplasmic space, between the cell membrane and cell wall © McGraw Hill LLC. 38  Gram-Positive Cell Wall 2 Gram-Positive Access the text alternative for slide images. © McGraw Hill LLC. 39  Gram-Negative Cell Wall 1 Inner and outer membranes and periplasmic space between them contains a thin peptidoglycan layer Outer membrane contains lipopolysaccharides (LPS) Lipid portion (endotoxin) may become toxic when released during infections May function as receptors and blocking immune response Contain porin proteins in upper layer – regulate molecules entering and leaving cell © McGraw Hill LLC. 40  Gram-Negative Cell Wall 2 Gram-Negative Access the text alternative for slide images. © McGraw Hill LLC. 41  Structures of Gram-Positive and Gram-Negative Bacterial Cell Walls Access the text alternative for slide images. © McGraw Hill LLC. 42  TABLE 4.1 Comparison of Gram-Positive and Gram- Negative Cell Walls Characteristic Gram-Positive Gram-Negative Number of major layers One Two Peptidoglycan Teichoic acid Lipopolysaccharide (LPS) Chemical composition Lipoteichoic acid Lipoprotein Mycolic acids and Peptidoglycan polysaccharides* Porin proteins Overall thickness Thicker (20 to 80 nm) Thinner (8 to 11 nm) Outer membrane No Yes Periplasmic space Narrow Extensive Permeability to molecules More penetrable Less penetrable *In some cells. © McGraw Hill LLC. 43  Concept Check: (3) Which of the following is NOT found in the Gram-Negative cell wall structure? A. Porins B. Teichoic Acids C. Periplasmic Space D. Lipopolysaccharides E. Peptidoglycan © McGraw Hill LLC. 44  Concept Check: (4) Which of the following is NOT found in the Gram-Negative cell wall structure? A. Porins B. Teichoic Acids C. Periplasmic Space D. Lipopolysaccharides E. Peptidoglycan Answer: B © McGraw Hill LLC. 45  The Gram Stain Differential stain that distinguishes cells with a gram-positive cell wall from those with a gram-negative cell wall Gram-positive - retain crystal violet and stain purple Gram-negative - lose crystal violet and stain red from safranin counterstain Important basis of bacterial classification and identification Practical aid in diagnosing infection and guiding drug treatment © McGraw Hill LLC. 46  Atypical Cell Walls Some bacterial groups lack typical cell wall structure, that is, Mycobacterium and Nocardia Gram-positive cell wall structure with lipid mycolic acid (cord factor) Pathogenicity and great deal of resistance to chemicals and dyes Basis for acid-fast stain used for diagnosis of infections caused by these microorganisms Some have no cell wall, that is, Mycoplasma Cell wall is stabilized by sterols Pleomorphic © McGraw Hill LLC. 47  Cell Membrane Structure 1 Phospholipid bilayer with embedded proteins–fluid mosaic model Functions in: Providing site for energy reactions, nutrient processing, and synthesis Passage of nutrients into the cell and discharge of wastes Cell membrane is selectively permeable © McGraw Hill LLC. 48  Cell Membrane Structure 2 Access the text alternative for slide images. © McGraw Hill LLC. 49  Inside the Bacterial Cell Cell cytoplasm: Dense gelatinous solution of sugars, amino acids, and salts 70 to 80% water Serves as solvent for materials used in all cell function © McGraw Hill LLC. 50  Nucleoid 1 Chromosome Single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell Plasmids Free small circular, double-stranded DNA Not essential to bacterial growth and metabolism Used in genetic engineering - readily manipulated and transferred from cell to cell © McGraw Hill LLC. 51  Nucleoid 2 Courtesy of Michael J. Daly © McGraw Hill LLC. 52  Bacterial Ribosome 1 Ribosomes Made of 60% ribosomal RNA and 40% protein Consist of two subunits: large and small Prokaryotic differ from eukaryotic ribosomes in size and number of proteins Site of protein synthesis Found in all cells © McGraw Hill LLC. 53  Bacterial Ribosome 2 Small subunit (30S) Large subunit (50S) Ribosome (70S) Access the text alternative for slide images. © McGraw Hill LLC. 54  Bacterial Internal Structures 1 Inclusions and granules Intracellular storage bodies Vary in size, number, and content Bacterial cell can use them when environmental sources are depleted © McGraw Hill LLC. 55  Bacterial Internal Structures 2 (a): Kwangshin Kim/Science Source © McGraw Hill LLC. 56  Bacterial Internal Structures 3 (c): D. Balkwill and D. Maratea © McGraw Hill LLC. 57  Bacterial Internal Structures 4 Cytoskeleton Many bacteria possess an internal network of protein polymers that is closely associated with the cell wall © McGraw Hill LLC. 58  Bacterial Internal Structures 5 Rut Carballido-Lopez/I.N.R.A. Jouy-en-Josas, Laboratoire de Génétique Microbienne © McGraw Hill LLC. 59  Bacterial Internal Structures 6 Endospores Inert, resting cells produced by some G+ genera: Clostridium, Bacillus, and Sporosarcina Have a 2-phase life cycle: Vegetative cell – metabolically active and growing Endospore – when exposed to adverse environmental conditions; capable of high resistance and very long-term survival © McGraw Hill LLC. 60  Bacterial Internal Structures 7 Sporulation - formation of endospores Hardiest of all life forms Withstands extremes in heat, drying, freezing, radiation, and chemicals Not a means of reproduction Germination - return to vegetative growth © McGraw Hill LLC. 61  Sporulation Cycle (photo): SJ Jones, CJ Paredes, B Tracy, N Cheng, R Sillers, RS Senger, ET Papoutsakis, “The transcriptional program underlying the physiology of clostridial sporulation”, Genome Biol, 2008. 9:R114. Access the text alternative for slide images. © McGraw Hill LLC. 62  Endospores Dehydrated, metabolically inactive Thick coat Longevity verges on immortality, 250 million years Resistant to ordinary cleaning methods and boiling Pressurized steam at 120°C for 20-30 minutes will destroy © McGraw Hill LLC. 63  Concept Check: (5) If you discover that the bacterium you’re studying stores phosphate, which of the following would you expect to contain the stored phosphate? A. Granules B. Ribosomes C. Plasmids D. Lipopolysaccharides E. Endospores © McGraw Hill LLC. 64  Concept Check: (6) If you discover that the bacterium you’re studying stores phosphate, which of the following would you expect to contain the stored phosphate? A. Granules B. Ribosomes C. Plasmids D. Lipopolysaccharides E. Endospores Answer: A © McGraw Hill LLC. 65  Bacterial Shapes, Arrangements, and Sizes Vary in shape, size, and arrangement but typically described by one of three basic shapes: Coccus – spherical Bacillus – rod Coccobacillus – very short and plump Vibrio – gently curved Spirillum – helical, comma, twisted rod, Spirochete – spring-like © McGraw Hill LLC. 66  Common Bacterial Shapes 1 a) Coccus (a): Source: Jeff Hageman, M.H.S./Janice Carr/CDC Access the text alternative for slide images. © McGraw Hill LLC. 67  Common Bacterial Shapes 2 b) Rod/Bacillus (b): Source: Janice Haney Carr/CDC Access the text alternative for slide images. © McGraw Hill LLC. 68  Common Bacterial Shapes 3 c) Vibrio (c): BSIP SA/Alamy Stock Photo Access the text alternative for slide images. © McGraw Hill LLC. 69  Common Bacterial Shapes 4 d) Spirillum (d): Source: Photo by De Wood, digital colorization by Chris Pooley, USDA-ARS Access the text alternative for slide images. © McGraw Hill LLC. 70  Common Bacterial Shapes 5 e) Spirochete (e): Source: Janice Haney Carr/CDC Access the text alternative for slide images. © McGraw Hill LLC. 71  Common Bacterial Shapes 6 f) Branching filaments (f): Source: Dr. David Berd/CDC Access the text alternative for slide images. © McGraw Hill LLC. 72  Common Bacterial Shapes 7 Key to Micrographs a) Staphylococcus aureus (10,000x) b) Legionella pneumophilia (6,500x) c) Vibrio cholerae (13,000x) d) Aquaspirillum (7,500x) e) Borrelia burgdorferi (10,000x) f) Streptomyces species (1,000x) © McGraw Hill LLC. 73  Pleomorphism 1 Variation in cell shape and size within a single species Some species are noted for their pleomorphism © McGraw Hill LLC. 74  Pleomorphism 2 Source: Dr. P.B. Smith/CDC Access the text alternative for slide images. © McGraw Hill LLC. 75  Bacterial Arrangements 1 Arrangement of cells is dependent on pattern of division and how cells remain attached after division: Cocci: Singles Diplococci – in pairs Tetrads – groups of four Irregular clusters – staphylococci and micrococci Chains – streptococci Cubical packets (sarcina) Bacilli: Diplobacilli – a pair Chains – streptobacilli Palisades © McGraw Hill LLC. 76  Bacterial Arrangements 2 The figure of “Bacterial Arrangements.” Access the text alternative for slide images. © McGraw Hill LLC. 77  Bacterial Arrangements 3 The figure of “Bacterial Arrangements” continues on this slide. Access the text alternative for slide images. © McGraw Hill LLC. 78  Bacterial Arrangements 4 The figure of “Bacterial Arrangements” continues on this slide. Access the text alternative for slide images. © McGraw Hill LLC. 79  The Size of Bacteria Access the text alternative for slide images. © McGraw Hill LLC. 80  Classification Systems for Prokaryotes 1. Microscopic morphology 2. Macroscopic morphology – colony appearance 3. Bacterial physiology 4. Serological analysis 5. Genetic and molecular analysis © McGraw Hill LLC. 81  Bacterial Taxonomy Based on Bergey’s Manual Bergey’s Manual of Systematic Bacteriology – five volume resource covering all known prokaryotes Classification based on genetic information – phylogenetic Two domains: Archaea and Bacteria Five major subgroups with 25 different phyla © McGraw Hill LLC. 82  Diagnostic Scheme for Medical Use Uses phenotypic qualities in identification Restricted to bacterial disease agents Divides bacteria based on cell wall structure, shape, arrangement, and physiological traits © McGraw Hill LLC. 83  Medically Important Bacteria 1 TABLE 4.4 Important Families and Genera of Bacteria, with Notes on Some Diseases* I. Bacteria with gram-positive cell wall structure (Phyla Firmicutes and Actinobacteria) Cocci in clusters or packets that are aerobic or facultative Family Staphylococcaceae: Staphylococcus (members cause boils, skin infections) Access the text alternative for slide images. © McGraw Hill LLC. 84  Medically Important Bacteria 2 The “TABLE 4.4” continues on this slide. Cocci in pairs and chains that are facultative Family Streptococcaceae: Streptococcus (species cause strep throat, dental caries) Anaerobic cocci in pairs, tetrads, irregular clusters Family Peptococcaceae: Peptococcus, Peptostreptococcus (involved in wound infections) Access the text alternative for slide images. © McGraw Hill LLC. 85  Medically Important Bacteria 3 The “TABLE 4.4” continues on this slide. Endospore-forming rods Family Bacillaceae: Bacillus (anthrax), Clostridium (tetanus, gas gangrene, botulism), Clostrioides (C-diff disease) Non-spore-forming rods Family Lactobacillaceae: Lactobacillus, Listeria (food infection), Erysipelothrix (erysipeloid) Access the text alternative for slide images. © McGraw Hill LLC. 86  Medically Important Bacteria 4 The “TABLE 4.4” continues on this slide. Family Propionibacteriaceae: Propionibacterium (involved in acne) Family Corynebacteriaceae: Corynebacterium (diphtheria) Family Mycobacteriaceae: Mycobacterium (tuberculosis, Hansen’s Disease) Access the text alternative for slide images. © McGraw Hill LLC. 87  Medically Important Bacteria 5 The “TABLE 4.4” continues on this slide. Family Nocardiaceae: Nocardia (lung abscesses) Family Actinomycetaceae: Actinomyces (dental infections) Family Streptomycetaceae: Streptomyces (important source of antibiotics) Access the text alternative for slide images. © McGraw Hill LLC. 88  Medically Important Bacteria 6 The “TABLE 4.4” continues on this slide. II. Bacteria with gram-negative cell wall structure (Phyla Proteobacteria, Bacteriodetes, Fusobacterium, Spirochaetes, Chlamydiae) Aerobic cocci Family Neisseraceae: Neisseria (gonorrhea, meningitis) Access the text alternative for slide images. © McGraw Hill LLC. 89  Medically Important Bacteria 7 The “TABLE 4.4” continues on this slide. Aerobic coccobacilli Family Moraxellaceae: Moraxella, Acinetobacter Anaerobic cocci Family Veillonellaceae: Veillonella (dental disease) Access the text alternative for slide images. © McGraw Hill LLC. 90  Medically Important Bacteria 8 The “TABLE 4.4” continues on this slide. Aerobic rods Family Pseudomonadaceae: Pseudomonas (pneumonia, burn infections) Miscellaneous rods (different families): Brucella (undulant fever), Bordetella (whooping cough), Francisella (tularemia), Coxiella (Q fever) Legionella (Legionnaires' disease) Access the text alternative for slide images. © McGraw Hill LLC. 91  Medically Important Bacteria 9 The “TABLE 4.4” continues on this slide. Facultative rods and vibrios Family Enterobacteriaceae: Escherichia, Edwardsiella, Citrobacter, Salmonella (typhoid fever), Shigella (dysentery), Klebsiella, Enterobacter, Serratia, Proteus, Yersinia (one species causes plague) Family Vibronaceae: Vibrio (cholera, food infection) Access the text alternative for slide images. © McGraw Hill LLC. 92  Medically Important Bacteria 10 The “TABLE 4.4” continues on this slide. Family Campylobacteraceae: Campylobacter (enteritis) Family Helicobacteraceae: Helicobacter (ulcers) Miscellaneous genera: Flavobacterium, Haemophilus (meningitis), Pasteurella (bite infections), Streptobacillus Access the text alternative for slide images. © McGraw Hill LLC. 93  Medically Important Bacteria 11 The “TABLE 4.4” continues on this slide. Aerobic rods Family Bacteroidaceae: Bacteroides, Fusobacterium, (anaerobic wound and dental infections) Helical and curviform bacteria Family Spirochaetaceae: Treponema (syphilis), Borrelia (Lyme disease), Leptospira (kidney infection) Access the text alternative for slide images. © McGraw Hill LLC. 94  Medically Important Bacteria 12 The “TABLE 4.4” continues on this slide. Obligate and facultative intracellular bacteria Family Rickettsiaceae: Rickettsia (Rocky Mountain spotted fever) Family Anaplasmataceae: Ehrlichia (human ehrlichosis) Family Chlamydiaceae: Chlamydia (sexually transmitted infection) Family Bartonellaceae: Bartonella (trench fever, cat scratch disease) Access the text alternative for slide images. © McGraw Hill LLC. 95  Medically Important Bacteria 13 The “TABLE 4.4” continues on this slide. III. Bacteria with no cell walls (Class Mollicutes) Family Mycoplasmataceae: Mycoplasma (pneumonia), Ureaplasma (urinary infection) Access the text alternative for slide images. © McGraw Hill LLC. 96  Concept Check: (7) Round bacterial cells growing in irregular clusters would be best described as: A. Streptococci B. Streptobacilli C. Staphylococci D. Tetrads © McGraw Hill LLC. 97  Concept Check: (8) Round bacterial cells growing in irregular clusters would be best described as: A. Streptococci B. Streptobacilli C. Staphylococci D. Tetrads Answer: C © McGraw Hill LLC. 98  Prokaryotes with Unusual Characteristics Free-living nonpathogenic bacteria Photosynthetic bacteria – use photosynthesis, can synthesize required nutrients from inorganic compounds Cyanobacteria (blue-green algae) Green and purple sulfur bacteria Gliding, fruiting bacteria © McGraw Hill LLC. 99  Cyanobacteria 1 Gram-negative cell walls Extensive thylakoids with photosynthetic chlorophyll pigments and gas inclusions © McGraw Hill LLC. 100  Green and Purple Sulfur Bacteria 1 Photosynthetic Contain photosynthetic pigment bacteriochlorophyll Do not give off oxygen as a product of photosynthesis © McGraw Hill LLC. 101  Gliding and Fruiting Bacteria Gram-negative Glide over moist surfaces © McGraw Hill LLC. 102  Unusual Forms of Medically Significant Bacteria 1 Obligate intracellular parasites Rickettsias Very tiny, gram-negative bacteria Most are pathogens Obligate intracellular pathogens Cannot survive or multiply outside of a host cell Rickettsia rickettisii – Rocky Mountain spotted fever © McGraw Hill LLC. 103  Unusual Forms of Medically Significant Bacteria 3 Chlamydias Tiny Obligate intracellular parasites Not transmitted by arthropods Chlamydia trachomatis – severe eye infection and one of the most common sexually transmitted diseases Chlamydia pneumoniae – lung infections © McGraw Hill LLC. 104  Archaea: The Other Prokaryotes 1 Constitute third Domain Archaea More closely related to Eukarya than to Bacteria Contain unique genetic sequences in their rRNA Have unique membrane lipids and cell walls © McGraw Hill LLC. 105  Archaea: The Other Prokaryotes 2 TABLE 4.5 Comparison of Three Cellular Domains Characteristic Bacteria Archaea Eukarya Cell type Prokaryotic Prokaryotic Eukaryotic Chromosomes Single, or few, circular Single, circular Several, linear 70S but structure is similar to Types of ribosomes 70S 80S 80S Unique ribosomal RNA signature sequences + + + Number of RNA sequences shared with Eukarya One Three Presence synthesis similar to Eukarya − + Presence of peptidoglycan in cell wall + − − Fatty acids with ester Long-chain, branched Fatty acids with ester Cell membrane lipids linkages hydrocarbons with ether linkages linkages Sterols in membrane −(some exceptions) − + © McGraw Hill LLC. 106  Archaea 1 Live in the most extreme habitats in nature, extremophiles Adapted to extreme temperature, salt, pH, and pressure Includes: methane producers, hyperthermophiles, extreme halophiles, and sulfur reducers © McGraw Hill LLC. 107  Concept Check: (9) Organisms in the Domain Archaea have peptidoglycan in their cell wall. A. True B. False © McGraw Hill LLC. 108  Concept Check: (10) Organisms in the Domain Archaea have peptidoglycan in their cell wall. A. True B. False Answer: B © McGraw Hill LLC. 109