1. BACTERIAL ANATOMY

2. Bacterial cellular anatomy
Bacterial cellular anatomy may be categorized into
     Structures found external to the cell envelope
        e.g., capsules, flagella, pili, glycocalyx, etc.
  Structures found associated with the cell envelope
e.g., the plasma membrane, the cell wall,  Structures found internal to the cell envelope
        e.g., cytoplasm, ribosomes, nuclear regions, etc.
      

3. Spherical is called coccus.
        
 Division along the same plane forms chains; 2 cocci together - Diplococcus
                              
  in chains - Streptococcus.
                                                    
 Division along 2 different planes - Tetrads
                                          
 Division along 3 planes regularly - Sarcinae
 Division along 3 planes irregularly - Staphylococci
                                                  
                  
          
        
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Copyright 1996 by the Faculty Resource Center Sylvester McKenna & Devabrata Mondal Long Island University, Brooklyn Campus   Last modified on January 10th, 1997

4. Rod shape is called Bacillus.
        
  Two bacilli together - Diplobacilli
                                  
 Chains of bacilli are called Streptobacilli
                           
 Palisades - Rods side by side or in X, V or Y figures
                                                
 Spiral shape that is rigid is called Spirillium.
                                        
 If the organism is flexible and undulating, it is called Spirochete.
                                  
Square shape is called Archaebacteria. Pleomorphism - Different forms of the same species.

5. Extra Cellular Matrix
It is attached to the cell wall and is made of polysaccharide or polypeptide, or a combination of both, to form a viscous layer. If it is thick, structured and adheres strongly to the cell wall, it is called a Capsule. If it is disorganized and loosely attached to the cell wall it is called a Slime layer. Both capsule and slime layer do not take up simple stains but can be observed by negative staining with India Ink or Negrosin. Functions of Capsules - (a). Adhere to surfaces to form colonies. (b). Antiphagocytic. (c). Antigenic. (d). Protect the organism from dehydration.

6. Structures for Movement
Made of the protein flagellin and consists of a filament and basal region. The basal region has a hook and a basal body which has a rod and rings. Gram positive organisms have 2 rings, one in the cell wall and one in the cell membrane. Gram negative organisms have 4 rings, 2 in the cell wall and 2 in the cell membrane.

8. Flagella have different numbers and arrangements:
 Monotrichous                 
 Lophotrichous
                
 Amphitrichous
                      
  Peritrichous
 Counterclockwise rotation is for smooth swimming towards an attractant. Clockwise rotation is for backward or reverse movement. With peritrichous flagella clockwise rotation results in tumbling to change direction.

9.                                  Found in Spirochetes and are similar to flagella, but are located between the cell wall and an outer sheath, and are attached to one end of the organism.

10. Pili Made of the protein pilin and project from the cell surface
Pili Made of the protein pilin and project from the cell surface. There are 2 types:
Sex or conjugation Pili for the transfer of extrachromosomal DNA between donor and recipient.
                             
 Attachment Pili or Fimbriae. There are many and are used for attachment to surfaces. Pili are virulence factors.

11. Cell wall (a) The cell wall of a bacteria (i) Is semirigid
(ii)    Is found externally to the plasma membrane
(iii)    Is responsible for maintaining the cell shape
(iv)  is responsible for protecting bacteria against osmotic lysis
(v)    Consists of peptidoglycan, murein
(vi)  Consists, in Gram-positive bacteria, additionally of teichoic acid
(b)    Though most bacteria possess cell walls, not all do

12. Gram-positive cell wall
(a) The Gram-positive cell wall differs from the Gram-negative cell wall in at least three ways
(i)  It is considerably thicker than the Gram-negative cell wall
(ii) It contains teichoic acid
(iii) It is directly exposed to the extracellular environment (or, at least, is not covered by an outer membrane)
(b)   The thickness of the cell wall allows the retention of the Gram stain thus accounting for the Gram-positive staining of these bacteria

13.    
Gram Positive:
Has a thick peptidoglycan (murein) layer and 2 classes of teichoic acids. Lipoteichoic acid which is on the surface, embedded in the peptidoglycan layer and is linked to the cytoplasmic membrane. Wall teichoic acid is on the surface and is linked to only the peptidoglycan layer. Teichoic acid is responsible for the antigenic determinant of the organism.
                                                                                         
 Gram Negative
Has a thin peptidoglycan (murein) layer with an outer membrane attached to the peptidoglycan layer by lipoproteins. The outer membrane is made of protein, phospholipid and lipopolysaccharide. In the lipopolysaccharide, the lipid portion is embedded in the phospholipid and the O antigen polysaccharide is on the surface. The lipid is called Lipid A and it is toxic, but the whole lipopolysaccharide is called an Endotoxin. The cell wall has channels called Porins for the transport of low molecular weight substances. Between the cytoplasmic membrane and the cell wall is a periplasmic space with hydrolytic enzymes, antibiotic inactivating enzymes and transport proteins.

14. GRAM NEGATIVE BACTERIA - CELL WALL

15. Gram-negative cell wall
(a)    The Gram-negative bacteria cell wall differs
from the cell wall of Gram-positive bacteria in terms of
(i)   The structure of the cell wall itself
(ii)   The covering of the cell wall by an outer membrane
(iii) The existence of a distinct periplasm
located between the outer membrane and the
inner membrane

16. Cytoplasmic Membrane Cell Wall
Made of a phospholipid bilayer with integral and peripheral proteins embedded. It maintains the selective permeability of the cell, has respiratory enzymes and during cell division the chromosome is linked to the cell membrane at a site called Mesosome.
Cell Wall
Protects and maintains the shape of the organism.
There are 2 basic cell walls, Gram positive and Gram negative.

17. Outer membrane
(a)  The outer membrane is a feature of Gram-negative bacteria
but not Gram-positive bacteria
(b)  The outer membrane is found externally to the cell wall
(c) The outer membrane helps protect the cell wall
and plasma membrane from environmental poisons
(d)   The outer membrane additionally surrounds)
the periplasmic space

18. Lipopolysaccharide (LPS, endotoxin)
(a)   A component of the outer-leaflet of the outer membrane of Gram-negative bacteria is LPS
(b)  LPS consists of polysaccharide and Lipid A (the latter anchors the LPS into the outer membrane)
(c)     Another name for Lipid A is endotoxin

19. Periplasmic space (periplasm)
(a)   The periplasm is the volume between the inner and outer
membranes
(b)     Gram-negative bacteria digest nutrients in the periplasm prior to the transport of the nutrients into the cytoplasm
(c)   (Gram-positive bacteria, by contrast, function more like fungi, employing exoenzymes that act beyond the cell to digest nutrients into forms that may then be taken up by the cell)
(d)  In addition to breaking down nutrients, the periplasm additionally serves as a region in which potentially harmful substances are broken down (i.e., destroyed)

20. Inner membrane
                Inner membrane is another name for the Gram-negative plasma membrane

23. Comparative Characteristics of Gram-Positive
and Gram-Negative Bacteria
Characteristic
Gram-positive
Gram-negative
Lipid and lipoprotein content
Low (acid-fast bacteria have lipids linked to peptidoglycan)
High (due to presence of outer membrane)
Flagellar structure
2 rings in basal body
4 rings in basal body
Toxins produced
Primarily exotoxins
Primarily endotoxins
Resistance to physical disruption
High
Low

24. Comparative Characteristics of Gram-Positive
and Gram-Negative Bacteria
Characteristic
Gram-positive
Gram-negative
Inhibition by basic dyes
High
Low
Suscep to anionic detergents
Resistance to sodium azide
Resistance to drying

25. Property Gram-positive Gram-negative Thickness of wall
thick (20-80 nm)
thin (10 nm)
Number of layers  1  2
Peptidoglycan (murein) content 
>50%
10-20%
Teichoic acids in wall 
present
absent
Lipid and lipoprotein content 
0-3%
58%
Protein content  9%
Lipopolysaccharide content  0 
13%
Sensitivity to Penicillin G 
yes
no (some exceptions
Sensitivity to lysozyme no

26. Cytoplasmic Structures
(a) Nucleoid - An area of concentrated DNA with no nuclear membrane.
The DNA is single circular, double stranded without proteins.
(b). Ribosomes - 30S and 50S to form a 70S complex.
(c). Plasmids - Extrachromosomal loops of DNA, some code for drug resistance, toxins and other factors.

27. Endospores Under environmental stress (lack of water, nutrients
etc.) some vegetative cells produce endospores e.g.
Clostridium and Bacillus. Spores can be dormant for
many years. They can survive extreme heat,
desiccation, radiation and toxic chemicals. However,
when conditions become favorable they revert to a
vegetative state. Spore germination is activated by
heat in the presence of moistures but the endospore must degrade the layers around the spore.

28. plasma membrane
The plasma membrane of prokaryotes and eukaryotes are functionally equivalent, though the prokaryote plasma membrane additionally serves in roles that eukaryotes reserve for internal membranes (e.g., cellular respiration)
(b)   Membranes consist of phospholipids which form into lipid bilayers because they have both a hydrophilic and a hydrophobic end
(c)  These lipid bilayers are impermeable to charged or large substances (e.g., ions or sugars); they are thus said to be selectively permeable

29. plasma membrane Active transport of molecules into the cell
Passive diffusion of other nutrients
Energy generation by oxidative phosphorylation
Synthesis of cell wall precurors
Secretion of enzymes & toxins

30. Movement across membranes
Small, hydrophobic substances typically can readily pass through plasma membranes by simple diffusion
(b) Passage of charged or large substances through lipid bilayers is mediated by integral membrane proteins
(c)  Other proteins found in or on membranes serve as enzymes

31. NUCLEIC ACIDS, AND THEIR PROTECTION
Nuclear region (nucleoid)
(a) This is simply where the bacterial DNA is located
(b) The nucleoid is not a membrane-enclosed region
Ribosomes
Ribosomes are the organelles responsible for making proteins

32. Endospores
(a) An endospore is a non-metabolizing bacterial cell that are highly resistant to numerous environment degradants including heat, drying, and all sorts of chemical insults
(b) Not all bacteria produce endospores
(c)  Endospores are produced within bacterial cells (hence the endo- part of their name)
(d) Sporulation = endospore formation
(e) Germination = endospore conversion back to a vegetative (i.e., metabolizing/growing) bacterial cell
(f) Much of the elaborate efforts employed to sterilize bacteria media or instruments is employed to create conditions that are sufficiently harsh that even endospores are killed (and hence the media or instrument has been sterilized)

33. Flagella
Monotrichous
(a)      Bacilli with a single flagellum located at a pole
Amphitrichous
(a)                    Bacilli with two flagella, one located at each pole
Lophotrichous
(a)  Bacilli with two or more flagella located at a single end or two or more each located at both ends
Peritrichous (a)     Bacilli with many flagella all over their surface
(36) Atrichous
(a)                    Bacteria lacking flagella
(b)                   

34. Chemotaxis (positive chemotaxis, negative
Chemotaxis is the movement toward or away from a chemical stimulus

35. PILI
(a) A rigid, proteinaceous projection from the surface of bacterium that is used to attach the bacterium to various surfaces
(b) By allowing adherence to cells and tissue the existence of pili allows bacteria to be pathogenic against certain hosts (i.e., those organisms to which they can attach)