Study Of Bacteria Flashcards
Unstained prepartion
Bacterial motility
Demonstration of spirachetes
Stained preparation
To find Structural detail of bacteria ,use stain which produce colour contract
Smear preparation
Smear drying
Fixation
Staining
Staining techniques
Simple stains
-ve staining
Impregnation
Differential staining
Simple staining
Same colour to all bacteria in the Smear
Basic dye-methylene blue
Negative staining
Dyes-nigrosin and Indian ink
Background get stained
Unstained bacteria stands out
Impregnation
To thicken the bacterial cells and structures to the surface by impregnation of silver
Eg,demonstration of flagella,spirachetes(bark grounded substances)
Differential
Different colours to the structures of bacteria
Eg,gram stain
Acid fast stain
Albert stain
Bacterial cell wall
Complex Rigid structure
Gives definite shape
Strength by peptidoglycon
3 parts of peptidoglycon
1,alternate chains of n acetyl glucosamine and n acetyl Muramic acid
2,id3ntical tetrapeptide chainto n acetyl muramic acid
3, identicalpentapeptide chain that cross bridges
Grame +ve and gram-ve
+ve
Thicker
Several layers of peptidoglycon
50 -90٪of dry weight of cell wall
Techoic acidand polysaccharides
-ve
Thinner
Structurally complex-lipoprorein,polysaccharides,peptidoglycon,
Outer membrane
Techoic acid
Cell wall -covalently bonded to cellwall peptidoglycon
Membrane-covalently bonded to cytoplasm8c membrane
Peptidoglycon layer in-ve bacteria
Single unit,thick (5% to 10%)
Lipoprotein layer-
Connect peptidoglycon to outer membrane
*high antibiotic resistance-large antibiotic molecule penetrate slowly
Outer membrane of gram -ve
Proteins like outer membrane proteins and porin protein
Lipopolysaccharide
Lipid A attached core polysaccharides
Constitute entotoxin -toxicity ( pyrogenesity,lethal effect,tissue necrosis)associated with it
Major surface antigen(antigenO)
Perisplasmic space
Space bw outer membrane and cytoplasmic membrane
Contains peptidoglycon and solution of proteins(gell like)
Types of fixation in staining techniques
Heat fixation and chemical fixation
Heat fixation-preserves overall morphology not the structures within the cells
*flameheating on air dried bacteria
Chemical fixation-protect the internal structures
Using ethanol,acetic acid,methanol,gluteraldehyde,mercuric chloride
*examination of blood smears
Dyes
Basic and acidic dyes
Basic dyes-methylene blue,Basic fusioncrystal violet,suffrage,malachite green
*binds to negative molecules like nucleicacid,proteins, bacterial cells
Acidic dyes-eosin,rosebengal acid fusion,phenolic hydroxyl does carboxyl
*binds to+ve molecules
To prevent Contamination of smears and transfer of organism from one Smear to another
Use smears individually rather than containers
To make stain smear
2 piece of glass rode with rubber tunings at tubings
Which are placed across a sink
*to pour strain-dropper bottles or plastic wash bottles can be used
*reagent bottles are named according to their labelling. Eg,toxic,flammable/corrosive
*after staining, smears are left air dry
Chemical used before /after the application of stain to stain properly
Mordant
Reaction of mordants
Basic mordants+acidic stains
Acidic mordants +Basic stains
Phenolic acid fast staining and iodine in gram staining eg of direct staining
Direct staining-simple staining without using mordant
Accentuator
Chemicals used to speed up reaction/make it more intensive
It cannot combine with stains
Eg,KOH in loefflers methylene blue
