IMED2001 Study Guide - Final Guide: Opportunistic Infection, Immunodeficiency, Coagulase
30 Jun 2018
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IMED2001: Revision Notes 1
Gram Stains:
-GN = pink!
-GP = purple!
4 reagents in GRAM STAINING:
1. crystal violet !
-(purple)!
2. fixative !
-(lugol’s iodine)!
3. Alcohol (for decolorisation) !
-= washes out CV+LI in GN bacteria!!!!
4. Counter stain (carbon fuchsin) !
--> stains GN pink!!
NOTE: (CV bind to LI to peptidoglycan** important because key difference between GN
and GP)
2 bacteria names (classic)
1. GP!
-Cluster of grapes !
-= eg. staphylococcus aureus !
-= purple!
2. GN!
-Escherichia (genus) coli (species) !
-= pink RODS!
* MAKE SURE THE UNDERLINE BOTH GENUS AND SPECIES IN EXAM)
Cells Walls:
-Difference between GN and GP bacteria cell walls: has two membranes with cell wall
between them !
-(outer and inner membrane with periplasmic space between them)!
-More discreet in GN, in GP is very tiny!
GP: !
-Peptidoglycan = THICK !
-From outside -> in: outer membrane, periplasmic space (with thick peptidoglycan
within), inner membrane = plasma membrane!
Document Summary
4 reagents in gram staining: crystal violet. = washes out cv+li in gn bacteria!: counter stain (carbon fuchsin) Note: (cv bind to li to peptidoglycan** important because key di erence between gn and gp) * make sure the underline both genus and species in exam) Di erence between gn and gp bacteria cell walls: has two membranes with cell wall between them. (outer and inner membrane with periplasmic space between them) More discreet in gn, in gp is very tiny. From outside -> in: outer membrane, periplasmic space (with thick peptidoglycan within), inner membrane = plasma membrane. From outside -> in: outer membrane, periplasmic space (with thin peptidoglycan within), inner membrane = plasma membrane. Because crystal violet gets xed by iodine in thick peptidoglycan layer. Strep - catalase negative, no bubbles: coagulase test. It only happens when person is immunocompromised)
