after culture stain we watch bacteria under oil immersion lenses we differentiate between Gram + Gram - cocci bacilli spiral filamentous bacterial size bacterial anatomy bacterial organelles cell wall function cell membrane function cell wall destruction cell kill bacteria membrane damage kill bacteria

1. Bacterial morphology
spherical
RODE
SHAPE
COMMA SHAPE
FILAMENTOUS
SPIRAL
COCCI
BACILLI
VIBRIO
CAMPYLOBACTER
ACTINOMYCES
HELICOBACTER
BACILLUS ANTHRACIS
STAPH AURAS

2. Culture and stain

3. Blood cell
Bacillus anthracis
• 7micron in diameter
• 1micron in
diameter

4. Bacterial cell size
Bacillus anthracis 3- 8 micron - *1-1.2 microcracks
staph auras 0.8- 1 micron smallest known famous
rickettsia prowazekii’s smallest
vaccinia virus 0.15- 0.25 micron
Influenzae 1*0.3 micron

5. Bacterial anatomy

7. Bacterial structure
• Capsule
• Flagella
• Fimbriae
• Cell wall
• Polysaccharide k antigen
• Motion H antigen flagellar
• antigen
• Attachment
• Give the shape of bacteria

8. Cell wall structure
Semirigid structure responsible for characteristic shape of
bacteria
Chemically macromolecular network called peptidoglycan
It is thick in Gam positive thin Gram negative

9. Cell wall structure
Semirigid structure responsible for
characteristic shape of bacteria
Chemically macromolecular network
called peptidoglycan
It is thick in Gam positive thin
Gram negative

12. Function of cell wall
Give bacteria characteristic shape
Protect cytoplasm
Determine gram staining nature
Gram positive
Game negative
Penicillin kills bacteria by inhibiting cell wall formation
Mycoplasmas has no cell wall so it is penicillin resistant

13. Gram stain
Gram positive
• Crystal violet complex with iodine
• Trapped in peptidoglycan cannot
be removed by decolorization
Gram negative
• Violet stain initially retained by
lipoprotein layer
• Decolorization dissolve lipoprotein
• Counterstaining result in staining
of decolorized bacteria with red
stain

15. Cell membrane living highly active thin double layered
internal to cell wall
chemically composed
of 60% protein 40% phospholipid
function of cell membrane
selective barrier selective
permeability some molecule pass other not
site for active metabolic process
site for electron transport system
has folds mesosomes increase total surface size

16. Damage to cell membrane
leads to bacterial death
Alcohol
disinfectant like
quaternary ammonium compound
antibiotics
polymyxin
nystatin
Damage to the cell membrane disturbs the
state of cell electrolytes, e.g. calcium, which
when constantly increased, induces
apoptosis. ... Ribosome damage: Damage to
ribosomal and cellular proteins such as
protein misfolding, Leading to apoptotic
enzyme activation.