Bacterial Morphology Arrangement

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Bacterial Morphology Arrangement

• 1. Bacilli
• a.Streptobacilli
• b. Bacilli
• 2. Cocci
• a. Cocci
• b. Doplococci
• c. Streptococci
• d. Staphylococci
• e. Sarcina ( 3D )
• f. Gaffkya ( 2D )

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Common Shapes Arrangement
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Bacterial morphologies (1)
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Bacterial morphologies (2)
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Bacterial morphologies (3)
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Bacterial Morphology Arrangement

• 3 Spirl
• a. Vibrio
• b. Spirillum
• c. Spirochete

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Bacterial morphologies (4)
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• Bacterial Cell Structures Functions

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Size relationships among prokaryotes
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Bacterial Cell Structure

• Appendages - fdlagella, pili or fimbriae
• Surface layers - capsule, cell wall, cell
  membrane
• Cytoplasm - nuclear material, ribosome, mesosome,
  inclusions etc.
• Special structure - endospore

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Bacterial Cell Structure
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• Appendages
• 1. flagella
• Some rods and spiral form have this.
• a). function motility
• b). origin cell membrane flagella attach to
  the cell by hook and basal body which consists
  of set(s) of rings and rods
• Gram - 2 sets of ring and rods, L, P,
  S, M rings and rods
• e.g. E. coli
• Gram S, M rings and rods
• e.g. B. megaterium

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Organ of bacterial locomotion
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Structure of the flagellum
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Flagella movement(1)
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Flagella movement(2)
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Flagella movement(3)
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• b).Origin (continued)
• The structure of the bacterial flagella allows it
  to spin like a propeller and thereby propel the
  bacterial cell clockwise or counter clockwise
  ( Eucaryotic , wave like motion.
• Bacterial flagella provides the bacterium with
  mechanism for swimming toward or away from
  chemical stimuli, a behavior is knows as
  CHEMOTAXIX, chemosenors in the cell envelope can
  detect certain chemicals and signal the flagella
  to respond.

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• c). position
• monotrichous
• lophotrichous
• peritrichous
• d). structure
• protein in nature subunit flagellin

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2. Pili or Fimbriae Shorter than flagella and
straighter , smaller. Only on some gram-
bacteria. a). function adhere. One of the
invasive mechanism on bacteria. Some pathogens
cause diseases due to this. If mutant
(fimbriae) not virulent. Prevent
phagocytosis.
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pili - sex factor. If they make pili, they are
or donors of F factor. It is necessary for
bacterial conjugation resulting in the transfer
of DNA from one cell to another. It have been
implicated in the ability of bacteria to
recognize specific receptor sites on the host
cell membrane. In addition, number of bacteria
virus infect only those bacteria have F pilus.
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• b). Origin Cell membrane
• c). Position common pili , numerous over the
  cell, usually called fimbriae sex pile, 1-4/cell
• d). Structure composed of proteins which can
  be dissociated into smaller unit
• Pilin . It belongs to a class of protein Lectin
  which bond to cell surface polysaccharide.

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• II. CELL SURFACE LAYER
• 1. Capsule or slime layer
• Many bacteria are able to secrete material that
  adheres to the bacterial cell but is actually
  external to the cell.
• It consists of polypeptide and polysaccharide on
  bacilli. Most of them have only polysaccharide.
  It is a protective layer that resists host
  phagocytosis. Medically important.

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2. Bacterial Cell Wall General structure
mucopolysaccharide i.e. peptidoglycan. It is
made by N-acetylglucosamine and N-acetylmuramic
acid. tetrapeptide ( L-alanine-
isoglutamine-lysine-alanine) is attached. The
entire cell wall structure is cross linked by
covalent bonds. This provide the rigidity
necessary to maintain the integrity of the
cell. N-acetylmuramic acid is unique to
prokaryotic cell.
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Cell walls of bacteria(2)
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Cell walls of bacteria(3)
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Cell walls of bacteria(4)
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Cell walls of bacteria(1)
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Structure of peptidoglycan(1)
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Structure of peptidoglycan(2)
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• (a). Gram positive bacterial cell wall
• Thick peptidoglycan layer
• pentaglycin cross linkage.
• Teichoic acid ribitol TA glycerol TA
• Some have peptioglycan teichoic acid.
• All have lipoteichoic acid.

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Function of TA Antigenic
determinant Participate in the supply of Mg to
the cell by binding Mg regulate normal cell
division. For most part, protein is not
found as a constituent of the G cell wall
except M protein on group streptococci
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Structure of the Gram-positive Cell Wall
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• (b) Gram -
• Thin peptidoglycan
• Tetrapeptide cross linkage
• A second membrane structure protein and
  lipopolysaccharide.
• Toxicity endotoxin on lipid A of
  lipopolysaccharide. glucosamine-
  glucosamine-long
• polysaccharide- repeated sequences of a few
  sugars (e.g. gal- mann-rham) n10-20 O antigen

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Structure of peptidoglycan(3)
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Toxicity endotoxin on lipid A of
lipopolysaccharide. glucosamine-
glucosamine-long FA FA FA FA
polysaccharide- repeated sequences of a few
sugars (e.g. gal- mann-rham) n10-20 O antigen
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Chemistry of LPS
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The Gram-negative outer membrane(1)
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The Gram-negative outer membrane(2)
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• 2. Cell Membrane
• Function
• a. control permeability
• b. transport es and protons for cellular
  metabolism
• c. contain enzymes to synthesis and transport
• cell wall substance and for metabolism
• d. secret hydrolytic enzymes
• e. regulate cell division.
• Fluid mosaic model. phospholipid bilayer
  and protein (structure and enzymatic function).
  Similar to eukaryotic cell membrane but some
  differs. e.g. sterols such as cholesterol in Euk
  not in Prok.

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The cytoplasmic membrane
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Functions of the cytoplasmic membrane(1)
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Functions of the cytoplasmic membrane(2)
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Transport proteins
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Classes of membrane transporting systems(1)
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Classes of membrane transporting systems(2)
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Classes of membrane transporting systems(3)
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• III. Cytoplasm
• 80 water, nucleic acids, proteins,
  carbohydrates, lipid and inorganic ions etc.
• 1. Bacterial chromosomes
• a single large circular double stranded DNA no
  histone proteins. The only proteins associated
  with the bacterial chromosomes are the ones for
  DNA replication, transcription etc.
• 2. Ribosome
• protein synthesis

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The bacterial chromosome and supercoiling
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• 3. Mesosomes
• A large invaginations of the plasma membrane,
  irregular in shape.
• a. increase in membrane surface, which may be
  useful as a site for enzyme activity in
  respiration and transport.
• b. may participate in cell replication by serving
  as a place of attachment for the bacterial
  chromosome.

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• 4. Inclusions
• Not separate by a membrane but distinct.
• Granules of various kinds
• glycogen,
• polyhydroxybutyric acid droplets (PHB)
• i.e. fat droplets
• inorganic metaphosphate (metachromatic
  granules) - in general, starvation of cell for
  almost any nutrients leads to the formation of
  this to serve as an intracellular phosphate
  reservoir.

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PHB
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• 5. Chromatophores
• Only in photosynthetic bacteria and blue green
  algae. Prok. no chloroplast, pigment found in
  lamellae located beneath the cell membrane.

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• IV. Special Structure
• Endospores
• Spore former sporobactobacilli and
  sporosarcinae - no medical importance. bacillus
  and clostridium have medical importance.
• Position median, sub-terminal and terminal
  have small water, high calcium content and
  dipicolinic acid (calcium dipicolinate)
• extremely resistant to heat, UV, chemicals etc.
  may be due to many S containing A.A for disulfide
  groups.

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The process of endospore formation

• After the active growth period approaching the
  stationary growth phase, a structure called
  forespore develops within the cells.
• It consists of coat, cortex and nuclear
  structure.

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Endospores
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Negatively Stained Bacillus (A) Vegetative Cell 
(B)  Endospore
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Dipicolinic acid
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Vegetative/spore-containing cells(1)
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Vegetative/spore-containing cells(2)
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Detailed stepsin endospore formation(1)
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Detailed stepsin endospore formation(2)
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Detailed stepsin endospore formation(3)