Study Of Bacteria

Question 1

Unstained prepartion

Answer 1

Bacterial motility
Demonstration of spirachetes

Question 2

Stained preparation

Answer 2

To find Structural detail of bacteria ,use stain which produce colour contract

Smear preparation
Smear drying
Fixation
Staining

Question 3

Staining techniques

Answer 3

Simple stains
-ve staining
Impregnation
Differential staining

Question 4

Simple staining

Answer 4

Same colour to all bacteria in the Smear
Basic dye-methylene blue

Question 5

Negative staining

Answer 5

Dyes-nigrosin and Indian ink
Background get stained
Unstained bacteria stands out

Question 6

Impregnation

Answer 6

To thicken the bacterial cells and structures to the surface by impregnation of silver

Eg,demonstration of flagella,spirachetes(bark grounded substances)

Question 7

Differential

Answer 7

Different colours to the structures of bacteria

Eg,gram stain
Acid fast stain
Albert stain

Question 8

Bacterial cell wall

Answer 8

Complex Rigid structure
Gives definite shape
Strength by peptidoglycon

Question 9

3 parts of peptidoglycon

Answer 9

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

Question 10

Grame +ve and gram-ve

Answer 10

+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

Question 11

Techoic acid

Answer 11

Cell wall -covalently bonded to cellwall peptidoglycon
Membrane-covalently bonded to cytoplasm8c membrane

Question 12

Peptidoglycon layer in-ve bacteria

Answer 12

Single unit,thick (5% to 10%)

Question 13

Lipoprotein layer-

Answer 13

Connect peptidoglycon to outer membrane
*high antibiotic resistance-large antibiotic molecule penetrate slowly

Question 14

Outer membrane of gram -ve

Answer 14

Proteins like outer membrane proteins and porin protein

Question 15

Lipopolysaccharide

Answer 15

Lipid A attached core polysaccharides
Constitute entotoxin -toxicity ( pyrogenesity,lethal effect,tissue necrosis)associated with it
Major surface antigen(antigenO)

Question 16

Perisplasmic space

Answer 16

Space bw outer membrane and cytoplasmic membrane
Contains peptidoglycon and solution of proteins(gell like)

Question 17

Types of fixation in staining techniques

Answer 17

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

Question 18

Dyes

Answer 18

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

Question 19

To prevent Contamination of smears and transfer of organism from one Smear to another

Answer 19

Use smears individually rather than containers

Question 20

To make stain smear

Answer 20

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

Question 21

Chemical used before /after the application of stain to stain properly

Answer 21

Mordant

Question 22

Reaction of mordants

Answer 22

Basic mordants+acidic stains
Acidic mordants +Basic stains

Question 23

Phenolic acid fast staining and iodine in gram staining eg of direct staining

Answer 23

Direct staining-simple staining without using mordant

Question 24

Accentuator

Answer 24

Chemicals used to speed up reaction/make it more intensive
It cannot combine with stains
Eg,KOH in loefflers methylene blue

Question 25

Differentiation/decolourisation

Answer 25

Regressive-after staining ,excessstain is removed or washed out
*basic stains-decolrise acid soln
*acidic stain -decolorise basic soln

Progressive
Without decoloriser,stains applied in sequence for specified time