لخّصلي

Morphology and Anatomy Of Bacteria Lec. 3 M.Sc. Shahalaa Ali MAIN TOPICS  At the end of the Lecture , the students will be able to understand: 1- Classification of bacteria depending on their morphology and Gram staining property. 2- Anatomy of Bacterial Cell. 3- Various Bacterial cell appendages and their functions. Classification of bacteria depending on their morphology and Gram staining property.  Most clinically relevant bacterial species range in size from 0.25 to 1 um in width and to 3 um in length ,  Thus requiring microscopy for visualization.  Just as bacterial species and genera vary in their metabolic processes , their cells also vary in size , morphology and cell – to –cell arrangements and chemical composition and structure of the cell wall.  Bacterial cell wall differences provide the basis for the Gram stain , a fundamental staining technique used in bacterial identification schemes.  This staining procedure separates almost all medically relevant bacteria into two general types: 1- gram –positive bacteria ( deep blue or purple) 2- gram – negative bacteria ( pink to red ) Shape of Bacteria .Cocci – arranged in group (clusters ) , pair or chains . .Bacilli – arranged in chain , pair , and some bacilli are curved , comma shaped , or cuneiform shaped . Anatomy of Bacteria cell  Structure of Bacterial Cell A- Cell Envelope 1- Cell Wall 2- Cell membrane ( plasma membrane , Cytoplasmic membrane ) B- Cytoplasm 1- Nucleoid 2- Ribosomes 3- Granules / Inclusion bodies 4- Mesosomes 5- Spores 6- Plasmids C- Appendages 1- Pilli 2- Flagella 3- Capsule Cell Wall  Is a tough & rigid structure surrounding the bacterium like a shell .  Weighs about 20-25 % of the dry weight of the cell .  Functions :  Accounts for shape of cell.  Provides protection to the cell against osmotic damage .  Confers rigidity upon bacteria .  Takes part in cell division .  Possesses target site for antibiotics , lysozymes and bacteriophages  Carries bacterial antigens that are important in virulence and immunity . S . No. Character 1 Thickness 2 Periplasmic space 3 Lipids 4 Teichoic acid 5 Peptidoglycan Gram Positive Thicker Absent Absent or small Present 16-80nm Gram Negative Thinner Present Present Absent 2nm Gram Positive Cell Wall  Peptidoglycan : thicker (16-80nm) than gram negative bacteria (2nm).  Teichoic acid : 1- Contains in a significant amount which is absent in gram negative . 2- Constitute major surface Ags . 3- Two types (wall teichoic acid and lipoteichoic acid ) . Gram Negative Cell Wall  Gram negative cell wall components -Lipoprotein layer -Outer membrane complex structure with following -LPS (Lipopolysaccharide) : 1- constitutes endotoxin of GNB 2- Determine major surface Ag 3- Toxicity (pyrogenicity , lethal effect , tissue necrosis ) -Periplasmic space -Peptidoglycan . Lipoprotein Layer:

• Connects the peptidoglycan to outer membrane
• . Outer membrane :
• Contains certain proteins called as OMP (outer membrane protein) .
• Target sites for phages , antibiotics and bacteriocins .
• .Lipopolysaccharides ( LPS ) :
• Consist of lipid A attached to a polysaccharide. -Constitutes the endotoxin of GNB .
• . Periplasmic space :
• Space between inner and outer membrane.
• Contains various binding proteins for specific substrates. Peptidoglycan : Rigid part of cell wall peptidoglycan mucopeptide( murein) composed of N-acetyl muramic acid and N-acetyl glucosaminde alternating in chains ,cross linked by peptide subunits. Bacterial with Defective Cell Wall  Synthesis of cell wall interfered or inhibited by many factors : _ Antibiotics _ Bacteriophage _ Lysozyme Cell membrane : Cytoplasmic Membrane . Is 5-10nm thick elastic semipermeable layer lies beneath for separating it from cell cytoplasm . . Acts as an osmotic barrier . . Acts as a semipermeable membrane controlling the inflow and outflow of metabolites to and from the protoplasm . . Contains enzymes necessary for cell wall synthesis (cytochrome oxidase , enzymes of tricarboxylic acid ) . Cytoplasm  Is a colloidal system containing variety of organic and inorganic solutes in a viscous watery solution .  Lacks: 1- Mitochondria 2- Endoplasmic reticulum  Contains: 1- 70% water of bacterial mass. 2- Ribosomes . 3- Mesosomes 4- Vacuoles. 5- Inclusions Ribosomes  Centre for protein synthesis.  Are composed of 1- Ribosomal RNA (rRNA) 2-Ribosomal proteins. Intracytoplasmic inclusions 1- Source of stored energy 2- Are grow under conditions of nutritional deficiency and disappear when deficient nutrients are supplied . 3- Volutin or metachromatic granules are +nt in C. dipyheria. Nucleoid  Bacteria don’t have true nucleus and there is no nuclear membrane or nucleolus.  Nucleiod is present irregularly shaped region containing DNA.  Bacterial DNA is haploid replicates by simple binary fission and maintains bacterial genetic characteristics.  Some bacteria may possess extra- nuclear genetic material in the cytoplasm consisting of DNA named as Plasmids or episomes . Capsule and Slime layer  Is amorphous viscid bacterial secretion of bacteria surrounds outer layer  when diffuses into surrounding medium and remains as a loose under marcated secretion as “Slime layer” when it is organized into a defined structure known as “Capsule” .  FUNCTIONS: 1- Antiphagocytic in nature. 2- Antigenic. 3- Virulence. Flagella :  Cytoplasmic appendages protruding through cell wall.  Composed of a protein (flagellin) (5-20um in length and 0.01- 0.02um in diameter) .  Organ of locomotion.  All motile bacteria contains either one or more flagella . Part and composition : . Three parts: 1- Flament 2- Hook 3- Basal body Arrangements / types 1 –Monotrichous. 2- Amphitrichous. 3- Lophotrichous. 4- Peritrichous. Fimbriae Hair like appendage projecting from cell surface -Also called as “Pili” . -Composed of protein called pilin. -Unrelated to motility.
• Functions: 1-Adhesion .2- Transfer of genetic material. Endospores  Are highly resistant resting stage formed in unfavorate environmental conditions .
• Depletion of nutrients.
• .Sporulation is not a method of reproduction as bacteria is not divide during sporulation . - .each vegetative cells one spore one vegetative bacterium. Morphology of Spore 1- Core 2- Forespore 3- Spore membrane 4- Spore cortex 5- Spore coat 6- Exosporium

Morphology and Anatomy
Of Bacteria
Lec. 3
M.Sc. Shahalaa Ali
MAIN TOPICS
 At the end of the Lecture , the students will be able to
understand:
1- Classification of bacteria depending on their morphology and
Gram staining property.
2- Anatomy of Bacterial Cell.
3- Various Bacterial cell appendages and their functions.
Classification of bacteria depending on their morphology and
Gram staining property.
 Most clinically relevant bacterial species range in size from 0.25 to 1 um in
width and to 3 um in length ,
 Thus requiring microscopy for visualization.
 Just as bacterial species and genera vary in their metabolic processes ,
their cells also vary in size , morphology and cell – to –cell arrangements
and chemical composition and structure of the cell wall.
 Bacterial cell wall differences provide the basis for the Gram stain , a
fundamental staining technique used in bacterial identification schemes.
 This staining procedure separates almost all medically relevant bacteria
into two general types:
1- gram –positive bacteria ( deep blue or purple)
2- gram – negative bacteria ( pink to red )
Shape of Bacteria
.Cocci – arranged in group (clusters ) , pair or chains .
.Bacilli – arranged in chain , pair , and some bacilli are curved ,
comma shaped , or cuneiform shaped .
Anatomy of Bacteria cell
 Structure of Bacterial Cell
A- Cell Envelope
1- Cell Wall
2- Cell membrane ( plasma membrane , Cytoplasmic membrane )
B- Cytoplasm
1- Nucleoid
2- Ribosomes
3- Granules / Inclusion bodies
4- Mesosomes
5- Spores
6- Plasmids
C- Appendages
1- Pilli
2- Flagella
3- Capsule
Cell Wall
 Is a tough & rigid structure surrounding the bacterium like a shell .
 Weighs about 20-25 % of the dry weight of the cell .
 Functions :
 Accounts for shape of cell.
 Provides protection to the cell against osmotic damage .
 Confers rigidity upon bacteria .
 Takes part in cell division .
 Possesses target site for antibiotics , lysozymes and bacteriophages
 Carries bacterial antigens that are important in virulence and
immunity .
S . No. Character 1 Thickness 2 Periplasmic space 3 Lipids 4 Teichoic acid 5 Peptidoglycan Gram Positive Thicker Absent Absent or small Present 16-80nm Gram Negative
Thinner
Present
Present
Absent
2nm
Gram Positive Cell Wall
 Peptidoglycan : thicker (16-80nm) than gram negative bacteria
(2nm).
 Teichoic acid :
1- Contains in a significant amount which is absent in gram negative .
2- Constitute major surface Ags .
3- Two types (wall teichoic acid and lipoteichoic acid ) .
Gram Negative Cell Wall
 Gram negative cell wall components
-Lipoprotein layer
-Outer membrane
complex structure with following
-LPS (Lipopolysaccharide) :
1- constitutes endotoxin of GNB
2- Determine major surface Ag
3- Toxicity (pyrogenicity , lethal effect , tissue necrosis )
-Periplasmic space
-Peptidoglycan
. Lipoprotein Layer:

• Connects the peptidoglycan to outer membrane


• . Outer membrane :


• Contains certain proteins called as OMP (outer membrane protein) .


• Target sites for phages , antibiotics and bacteriocins .


• .Lipopolysaccharides ( LPS ) :


• Consist of lipid A attached to a polysaccharide.
  -Constitutes the endotoxin of GNB .


• . Periplasmic space :


• Space between inner and outer membrane.


• Contains various binding proteins for specific substrates.
  Peptidoglycan :
  Rigid part of cell wall peptidoglycan mucopeptide( murein)
  composed of N-acetyl muramic acid and N-acetyl glucosaminde
  alternating in chains ,cross linked by peptide subunits.
  Bacterial with Defective Cell Wall
   Synthesis of cell wall interfered or inhibited by many factors :
  _ Antibiotics
  _ Bacteriophage
  _ Lysozyme
  Cell membrane : Cytoplasmic Membrane
  . Is 5-10nm thick elastic semipermeable layer lies beneath for
  separating it from cell cytoplasm .
  . Acts as an osmotic barrier .
  . Acts as a semipermeable membrane controlling the inflow and
  outflow of metabolites to and from the protoplasm .
  . Contains enzymes necessary for cell wall synthesis (cytochrome
  oxidase , enzymes of tricarboxylic acid ) .
  Cytoplasm
   Is a colloidal system containing variety of organic and inorganic
  solutes in a viscous watery solution .
   Lacks:
  1- Mitochondria
  2- Endoplasmic reticulum
   Contains:
  1- 70% water of bacterial mass.
  2- Ribosomes .
  3- Mesosomes
  4- Vacuoles.
  5- Inclusions
  Ribosomes
   Centre for protein synthesis.
   Are composed of
  1- Ribosomal RNA (rRNA)
  2-Ribosomal proteins.
  Intracytoplasmic inclusions
  1- Source of stored energy
  2- Are grow under conditions of nutritional deficiency and disappear
  when deficient nutrients are supplied .
  3- Volutin or metachromatic granules are +nt in C. dipyheria.
  Nucleoid
   Bacteria don’t have true nucleus and there is no
  nuclear membrane or nucleolus.
   Nucleiod is present irregularly shaped region
  containing DNA.
   Bacterial DNA is haploid replicates by
  simple binary fission and maintains bacterial genetic
  characteristics.
   Some bacteria may possess extra- nuclear genetic
  material in the cytoplasm consisting of DNA named as
  Plasmids or episomes .
  Capsule and Slime layer
   Is amorphous viscid bacterial secretion of bacteria
  surrounds outer layer
   when diffuses into surrounding medium and remains as a loose
  under marcated secretion as “Slime layer” when it is
  organized into a defined structure known as “Capsule”
  .
   FUNCTIONS:
  1- Antiphagocytic in nature.
  2- Antigenic.
  3- Virulence.
  Flagella :
   Cytoplasmic appendages protruding through cell wall.
   Composed of a protein (flagellin) (5-20um in length and 0.01-
  0.02um in diameter) .
   Organ of locomotion.
   All motile bacteria contains either one or more flagella .
  Part and composition :
  . Three parts:
  1- Flament
  2- Hook
  3- Basal body
  Arrangements / types
  1 –Monotrichous.
  2- Amphitrichous.
  3- Lophotrichous.
  4- Peritrichous.
  Fimbriae
  Hair like appendage projecting from cell surface
  -Also called as “Pili”
  .
  -Composed of protein called pilin.
  -Unrelated to motility.


• Functions: 1-Adhesion .2- Transfer of genetic material.
  Endospores
   Are highly resistant resting stage formed in unfavorate
  environmental conditions .


• Depletion of nutrients.


• .Sporulation is not a method of reproduction as bacteria
  is not divide during sporulation .


• .each vegetative cells one spore one
  vegetative bacterium.
  Morphology of Spore
  1- Core
  2- Forespore
  3- Spore membrane
  4- Spore cortex
  5- Spore coat
  6- Exosporium