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BACTERIAL MORPHOLOGY: PROCARYOTIC AND EUCARYOTIC CELLS Chapter 4.

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Presentation on theme: "BACTERIAL MORPHOLOGY: PROCARYOTIC AND EUCARYOTIC CELLS Chapter 4."— Presentation transcript:

1 BACTERIAL MORPHOLOGY: PROCARYOTIC AND EUCARYOTIC CELLS Chapter 4

2 Eucaryotic cells any organism with a fundamental cell type containing membrane- enclosed organelles any organism with a fundamental cell type containing membrane- enclosed organelles

3 Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells Comparing Prokaryotic and Eukaryotic Cells –Prokaryote comes from the Greek words for prenucleus. –Eukaryote comes from the Greek words for true nucleus.

4 One circular chromosome, not in a membrane One circular chromosome, not in a membrane No histones No histones No organelles No organelles Peptidoglycan cell walls Peptidoglycan cell walls Binary fission Binary fission ProkaryoteEukaryote Paired chromosomes, in nuclear membrane Paired chromosomes, in nuclear membrane Histones Histones Organelles Organelles Polysaccharide cell walls Polysaccharide cell walls Mitotic spindle Mitotic spindle

5 Average size: µm  µm Average size: µm  µm Basic shapes: Basic shapes: Procaryotes (Bacteria)

6 Protozoan (eucaryote)

7 Procaryotic cells any organism with a fundamental cell type without nucleus any organism with a fundamental cell type without nucleus

8 Unusual shapes Unusual shapes –Star-shaped Stella –Square Haloarcula Most bacteria are monomorphic Most bacteria are monomorphic A few are pleomorphic A few are pleomorphic Figure 4.5

9 Bacteria (procaryote)

10 Procaryotic cells (cont.) Bacteria Bacteria –Differentiation by: Morphology, composition, nutritional requirements, and biochemical activities and source of energy Morphology, composition, nutritional requirements, and biochemical activities and source of energy

11 Shapes of bacteria coccus (spheres) coccus (spheres) bacillus (rods) bacillus (rods) spiral (twisted) spiral (twisted) pleomorphic (several) pleomorphic (several)

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19 Pairs: diplococci, diplobacilli Pairs: diplococci, diplobacilli Clusters: staphylococci Clusters: staphylococci Chains: streptococci, streptobacilli Chains: streptococci, streptobacilli Arrangements

20 Arrangements of cocci Divide in: Divide in: –one plane=diplococci –two planes=tetrads –three planes=sarcineae –multiple=staphylococci

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27 Structures external to the bacterial cell wall Glycocalyx Glycocalyx Flagella Flagella Axial filaments Axial filaments Fimbriae and pili Fimbriae and pili

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29 Glycocalyx Capsule (firm) or slime layer (loose) Capsule (firm) or slime layer (loose) –polysaccharide and/or polypeptide –Inhibits phagocytosis –Attaches to host surfaces –Protects against desiccation

30 Outside cell wall Outside cell wall Usually sticky Usually sticky A capsule is neatly organized A capsule is neatly organized A slime layer is unorganized & loose A slime layer is unorganized & loose Extracellular polysaccharide allows cell to attach Extracellular polysaccharide allows cell to attach Capsules prevent phagocytosis Capsules prevent phagocytosis Glycocalyx Figure 4.6a, b

31 Bacterial glycocalyx

32 Streptococcus pneumoniae capsule

33 Outside cell wall Outside cell wall Made of chains of flagellin Made of chains of flagellin Attached to a protein hook Attached to a protein hook Anchored to the wall and membrane by the basal body Anchored to the wall and membrane by the basal body They propel bacteria around They propel bacteria aroundFlagella

34 Flagella

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36 Rotate flagella to run or tumble Rotate flagella to run or tumble Move toward or away from stimuli (taxis) Move toward or away from stimuli (taxis) Flagella proteins are H antigens (e.g., E. coli O157:H7) Flagella proteins are H antigens (e.g., E. coli O157:H7) Motile Cells

37 Peritrichous Monotrichous Lophotrichous

38 Types of Flagella

39 Main function: to propel bacteria to and from area’s of nutrients/toxic environments

40 Types of Flagella

41 Axial filaments Present in spiral cells Present in spiral cells Similar to flagella, but they wrap around the cell Similar to flagella, but they wrap around the cell Corkscrew motion enables a bacterium such as T.pallidum (causative agent of Syphilis) to move effectively through body fluids (vaginal secretions) Corkscrew motion enables a bacterium such as T.pallidum (causative agent of Syphilis) to move effectively through body fluids (vaginal secretions)

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43 Fimbriae, pili and sex pili Short thin appendages Short thin appendages –Fimbriae and pili Help cells to adhere to surfaces Help cells to adhere to surfaces –Sex pili Bridge between bacterial cells for DNA transfer Bridge between bacterial cells for DNA transfer

44 DNA transfer through a sex pili

45 Fimbriae

46 Fimbriae allow attachment to teeth, stones in creeks, plastic catheter's in hospitals Fimbriae allow attachment to teeth, stones in creeks, plastic catheter's in hospitals Pili are used to transfer DNA from one cell to another Pili are used to transfer DNA from one cell to another Fimbriae

47 E. coli Intestinal mucosa

48 Cell wall Surrounds the plasma membrane Surrounds the plasma membrane –Protects the cell from osmotic pressure changes –Lattice formed by peptidoglycan (murein)

49 Prevents osmotic lysis Prevents osmotic lysis Made of peptidoglycan (in bacteria) Made of peptidoglycan (in bacteria) Cell Wall Figure 4.6a, b

50 Peptidoglycan (murein) N-acetylglucosamine (NAG) N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM) N-acetylmuramic acid (NAM) –repeating disaccharides joined by polypeptides

51 Polymer of disaccharide N-acetylglucosamine (NAG) & N- acetylmuramic acid (NAM) Polymer of disaccharide N-acetylglucosamine (NAG) & N- acetylmuramic acid (NAM) Linked by polypeptides Linked by polypeptides Peptidoglycan Figure 4.13a

52 N-acetylglucosamine (NAG) N-acetymuramic acid (NAM) Peptide bridge

53 NAG NAM Peptide bridge

54 Gram-positive cells several well-organized peptidoglycan layers several well-organized peptidoglycan layers teichoic acids teichoic acids

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56 Gram positive

57 S. aureus

58 Teichoic acids: Teichoic acids: –Lipoteichoic acid links to plasma membrane –Wall teichoic acid links to peptidoglycan May regulate movement of cations May regulate movement of cations Polysaccharides provide antigenic variation Polysaccharides provide antigenic variation Gram-Positive cell walls Figure 4.13b

59 Gram Negative Cells

60 Gram-negative cells a thin poorly-organized peptidoglycan layer a thin poorly-organized peptidoglycan layer outer membrane outer membrane –lipoprotein-lipopolysaccharide-phospholipid (LPS)

61 Gram-negative cells (cont.) outer membrane outer membrane –protects against phagocytosis, penicillin  sugars in LPS act as antigens  lipid A acts as endotoxin

62 Outer membrane peptidoglycan Gram negative bacteria

63 Figure 4.13b, c

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65 Gram negative E. coli

66 Gram positive No outer membrane Gram negative With an outer membrane

67 Lipopolysaccharides, lipoproteins, phospholipids. Lipopolysaccharides, lipoproteins, phospholipids. Forms the periplasm between the outer membrane and the plasma membrane. Forms the periplasm between the outer membrane and the plasma membrane. Protection from phagocytes, complement, antibiotics. Protection from phagocytes, complement, antibiotics. O polysaccharide antigen, e.g., E. coli O157:H7. O polysaccharide antigen, e.g., E. coli O157:H7. Lipid A is an endotoxin. Lipid A is an endotoxin. Porins (proteins) form channels through membrane Porins (proteins) form channels through membrane Gram-Negative Outer Membrane

68 Thick peptidoglycan Thick peptidoglycan Teichoic acids Teichoic acids In acid-fast cells, contains mycolic acid In acid-fast cells, contains mycolic acid Thin peptidoglycan Thin peptidoglycan No teichoic acids No teichoic acids Outer membrane Outer membrane

69 Figure 4.13b, c

70 Mycoplasmas Mycoplasmas –Lack cell walls –Sterols in plasma membrane Archaea Archaea –Wall-less, or –Walls of pseudomurein (lack NAM and D amino acids) Atypical Cell Walls

71 Lysozyme digests disaccharide in peptidoglycan Lysozyme digests disaccharide in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycan Damage to Cell Walls

72 Damage to cell walls Lysozyme degrades peptidoglycans Lysozyme degrades peptidoglycans Penicillin and other antibiotics affect synthesis of cell wall Penicillin and other antibiotics affect synthesis of cell wall

73 Plasma Membrane

74 Figure 4.14a

75 Plasma Membrane Phospholipid bilayer Phospholipid bilayer Peripheral proteins Peripheral proteins Integral proteins Integral proteins Transmembrane proteins Transmembrane proteins Figure 4.14b

76 Membrane is as viscous as olive oil. Membrane is as viscous as olive oil. Proteins move to function Proteins move to function Phospholipids rotate and move laterally Phospholipids rotate and move laterally Fluid Mosaic Model Figure 4.14b

77 THE GRAM STAIN

78 Crystal violet-iodine crystals form in cell Crystal violet-iodine crystals form in cell Gram-positive Gram-positive –Alcohol dehydrates peptidoglycan –CV-I crystals do not leave Gram-negative Gram-negative –Alcohol dissolves outer membrane and leaves holes in peptidoglycan –CV-I washes out Gram Stain Mechanism

79 Gram positive Gram negative Gram stain technique

80 Know all four steps and why you are doing them!!!

81 REVIEW We are conditioned to think of bacteria as invisable, potentially harmful little creatures!! We are conditioned to think of bacteria as invisable, potentially harmful little creatures!! Actually, relatively few species of bacteria cause disease in humans, animals and plants!! Actually, relatively few species of bacteria cause disease in humans, animals and plants!! After this course you will realize that without bacteria, much of life as we know it would not be possible !! After this course you will realize that without bacteria, much of life as we know it would not be possible !!

82 Bacteria and Archaea Bacteria Procaryotes

83 The Prokaryotes: Domains Bacteria and Archaea One circular chromosome, not in a membrane One circular chromosome, not in a membrane No histones No histones No organelles No organelles Peptidoglycan cell walls Peptidoglycan cell walls Binary fission Binary fission

84 THE PROTEOBACTERIA Remember all organisms made up of eukaryotic cells probably evolved from bacterialike organism, which were the earliest forms of life!!! Remember all organisms made up of eukaryotic cells probably evolved from bacterialike organism, which were the earliest forms of life!!! Include most of the G-, chemoheterotrophic bacteria Include most of the G-, chemoheterotrophic bacteria Have arisen from a common photosynthetic ancestor Have arisen from a common photosynthetic ancestor

85 Proteobacteria Proteobacteria –Mythical Greek god, Proteus, who could assume many shapes –Gram- negative Domain Bacteria

86 Alpha (  )--Proteobacteria Are capable of growth at very low levels of nutrients Are capable of growth at very low levels of nutrients Have unusual morphology, including protrusions such as stalks or buds known as prosthecae Have unusual morphology, including protrusions such as stalks or buds known as prosthecae They include agriculturally important bacteria capable of inducing nitrogen fixation They include agriculturally important bacteria capable of inducing nitrogen fixation

87 Human pathogens: Human pathogens: –Bartonella –B.hensela Cat-scratch disease –BrucellaBrucellosis The  (alpha) Proteobacteria

88 Rickettsias Rickettsias, Coxiella and Chlamydia are obligate intracellular parasites Rickettsias, Coxiella and Chlamydia are obligate intracellular parasites They only reproduce inside a mammalian cell They only reproduce inside a mammalian cell

89 Obligate intracellular parasites: Obligate intracellular parasites: –Ehrlichia -  Tick-borne, ehrlichiosis –Rickettsia -  Arthropod-borne, spotted fevers R. prowazekii  Epidemic typhus (lice) R. prowazekii  Epidemic typhus (lice) R. typhi  Endemic murine typhus (rat fleas) R. typhi  Endemic murine typhus (rat fleas) R. rickettsii  Rocky Mountain Spotted Fever(ticks) R. rickettsii  Rocky Mountain Spotted Fever(ticks) The  (alpha) Proteobacteria

90 The  (alpha) Proteobacteria (Rickettsias) Figure 11.1

91 Wolbachia. Live in insects and other animals Wolbachia. Live in insects and other animals Belongs to the Rickettsia genera Belongs to the Rickettsia genera The  (alpha) Proteobacteria

92 Have prosthecae: Have prosthecae: –Caulobacter. Stalked bacteria found in low nutrient lakes as well as in laboratory waterbaths— stalk helps in the absorption of nutrients –Hyphomicrobium. Budding bacteria found in lakes— when nutrients are low, stalk size increases to provide greater area for nutrient absorption The  (alpha) Proteobacteria

93 Plant pathogen: Plant pathogen: –Agrobacterium (invades plants & causes crown gall) –It inserts a plasmid into plant cells, inducing the tumor –Researchers are very interested in this organism b/c plant cells are very difficult to penetrate The  (alpha) Proteobacteria

94 Chemoautotrophic: Chemoautotrophic: –Oxidize nitrogen for energy –Fix CO 2 Nitrobacter. NH 3 +  NO 2 – Nitrobacter. NH 3 +  NO 2 – Nitrosomonas. NO 2 –  NO 3 – Nitrosomonas. NO 2 –  NO 3 – The  (alpha) Proteobacteria

95 Nitrogen-fixing bacteria: Nitrogen-fixing bacteria: –Azospirillum Grow in soil, using nutrients excreted by plants Grow in soil, using nutrients excreted by plants Fix nitrogen Fix nitrogen –Rhizobium Fix nitrogen in the roots of plants Fix nitrogen in the roots of plants The  (alpha) Proteobacteria Figure 27.5

96 Are industrially important Are industrially important They produce acetic acid (vinegar) from ethyl alcohol: They produce acetic acid (vinegar) from ethyl alcohol: –Acetobacter –Gluconobacter The  (alpha) Proteobacteria


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