1. Bacterial morphology

2. Structure of the bacterial cell
I- Bacterial cell wall
1) definition
2) function
3) chemical composition
4) Difference between G +ve & G -ve
5) Mycoplama
6) L form

3. Structure of the bacterial cell
I- Bacterial cell wall
1) definition
-It's the outermost basic component of all bacteria
- It's multilayered structure located external to cytoplasmic membrane

4. Structure of the bacterial cell
I- Bacterial cell wall
2) function
- Maintain the shape: rigid structure
- Protect and support C M: Osmotically insensitive
- Has role in replication: transverse septum
-Responsible stain affinity: G +ve or G –ve

5. I- Bacterial cell wall 3) chemical composition
A- In gram +ve bacteria: Thick but simple
1 – Peptidoglycan (P. G):
- This is the basic structure of cell wall
- Composed of about 40 sheet or 50% of cell wall content
- Formed of repeating unit of N acetyl-D- glucosamin and
N acetyl muramic acid. That form sheet surrounding CM
2 - Techoic acid:
- Formed of polymer of ribitol and glycerol, mixed on both
sides of P.G
- it mediate adherence of bacteria to mucosal surface
both P.G and Techoic acid are the major surface antigen in gram +ve bacteria
NAG
NAG
NAM
NAM

6. I- Bacterial cell wall 2) chemical composition
A- In gram +ve bacteria: Thick but simple

7. I- Bacterial cell wall 2) chemical composition
B- In gram -ve bacteria: thin but complex
1 – Peptidoglycan (P. G): (mention its structure)
- It form thin layer formed of 1or 2 sheets and constitute about 5-10 % of cell wall of G-ve cell wall
2- Outer membrane:
- formed of phospholipids bilayer and proteins (similar to Cytoplasmic membrane)
3- Lipoprotein: cross link P G and outer membrane

8. I- Bacterial cell wall 4- Lipopolysacchrides (LPS):
2) chemical composition
4- Lipopolysacchrides (LPS):
- attached to outer membrane
- formed of inner part called lipid A and the polysaccharide core then
- polysaccharide side chain that called somatic (O) antigen.
- LPS is called endotoxin as when it is released after bacterial lysis
- it induce toxic manifestation called endotoxic shock syndrome
5- Periplasmic space:
- The space between cytoplasmic membrane and outer membrane
- It contain PG, lipoprotein, and gel like structure contain many
enzymes as beta Lactamase enzyme
core
Lipid A
Outer M

9. Structure of the bacterial cell

10. Diference in Structure

11. Bacteria deficient in cell wall
* Definition:
they are bacteria that don’t have cell wall
*Types: cell wall deficient bacterial may be natural as mycoplasma or
induced as L-form that are formed in presence of cell wall inhibitor as
lysozyme or drug as penicillin that interfere with P G
* L form may be of two types
1- Spheroplast: formed from G -ve bacteria and sill contain outer membrane
2- protoplast: formed from G +ve bacteria and don’t contain outer m.
* Importance of L form:
It may be formed during antibiotic treatment so it become resistant to its action then their reversion to the walled stat leads to relapse and chronicity of infection

12. Bacteria deficint in cell wall
Comparison:
Mycoplasma
L- form
Table 2
It’s bacteria that naturally devoid of cell wall.
It’s bacteria é removed or damaged cell wall.
Definition
No external influence.
Due to inhibitor in the media as penicillin or lysozyme
Cause
Can’t
Can revert it the inhibitor removed
Reverting to walled state
Solid or fluid é cholesterol
Grow only on solid media
Media
Less
More fragile
Fragility
Some species may cause respiratory or genital diseases.
Responsible for chronicity of infection and drug resistance
Importance

13. Structure of the bacterial cell
II- Bacterial cytoplasmic M
1) composition
2) functions
3) Mesosomes
4) intracytoplasmic structures

14. II- Bacterial cytoplasmic M
1) composition
Composition:
phospholipids bilayer and proteins but unlike eukaryotes doesn’t contain sterols except in Mycoplasma
Mesosomes:
they are invaginations of the cytoplasmic
membrane into the cytoplasm the are
involved in many function as respiration,
cell division and spore formation.

15. II- Bacterial cytoplasmic M
2) Functions
1- Selective permeability: for nutrients through
- Simple diffusions: down to concentration gradient, no energy
- Facilitated diffusion: for large molecules also no energy.
- Active transport: against concentration gradient so energy is needed.
2- Respiration: by oxidative phosphorylation and electron transport, instead of Mitochondria in eukaryotes.
3- Excretion of extracelluar enzymes and toxins

16. II- Bacterial cytoplasmic M
2) Functions
4- Role in cell division as it provide
- Site of attachment of chromosome before duplication
- Synthesis of cell wall septum for separation of the two cells
5- Provide enzymes and lipid carrier for cell wall synthesis
6- Chemotactic for bacterial response to man attractant or repellant through its receptors e.g. attraction of motile
bacteria toward glucose

17. II- Bacterial cytoplasmic M
4)intracytoplasmic structures
1- Nucleoid body : formed of single circular, chromosomecoiled on itself without nuclear membrane.
2- Plasmid: it is extra-chromosomal double stranded circular DNA smaller than chromosome and carries genes not essential for life.
3- Ribosome: it is of 70s type formed of 2 subunits 50s and 30s It is the site of protein synthesis.
4- Inclusion: many types of inclusion may present as volutin granules which are food reserve for ATP production.

18. Structure of the bacterial cell
III- Bacterial Capsule
1) Definition
2) composition
3) Importance
4) Glycocalyx

19. Bacterial Capsule 1) Definition:
it is the outermost well defined layer in capsulated organism while if ill defined it is called glycocalyx
2) Composition:
it is in vivo structure mostly formed of polysaccharides except in B. antracis formed of polypeptides

20. Bacterial Capsule 3) Importance (functions)
1- Virulence factor: antiphagocytic factor
2-Protection of call wall from antibacterial agent as lysozyme and bacteriophage
3 - Help bacterial attachment and biofilm formation (glycocalyx)
5 - Reservoir for certain nutrient
6 - used in diagnosis
7 - used in formation of vaccines.
8 - used in serotyping

21. Structure of the bacterial cell
IV- Bacterial Flagella
1 - structure
2 - importance
3 - types

22. Bacterial Flagella
Structure
- these are long thin filamentous appendages that are attached to the cell wall and C.M by basal body.
- consist of protein called flagilin which is antigenic and called (H) antigen.
function : these are organ of motility in motile bacteria that move toward nutrient and attractant (chemotaxis).

23. Bacterial Flagella
- Types
According to distribution: many distribution form present but it is constant in the same species, it may be
A - monotrichous,
B - lophotrichous
C - amphotrichous,
D - peritrichous

24. Bacterial Flagella
1) structure
- importance
- types

25. Structure of the bacterial cell
V- Bacterial pili
Definition:
these are hair like projections of cell similar
to flagella but smaller
* Composition: formed of protein called pilin
*Types and Function: 2 types of 2 different functions
1- Ordinary pili: mediate adherence of the organism
to the epithelial surface e.g. N. gonorrhea adhere pili
to mucosa of urethra
2- Sex pili: responsible of conjugation (see Genetic).