Gram staining Flashcards
Thick peptidoglycan cell wall
Gram + or - ?
Gram +
Gram +
- thick peptidoglucan layer
- no outere membrain layer
No outer Membrain
Gram + or - ?
Gram +
Penicilin provents cross linking chains from forming
Gram + or - ?
Gram +
Penicilin inhibits enzyme from working
Gram + or - ?
Gram +
Cell wall synthisis is disrupted
affected by antibiotics
Gram + or - ?
Gram +
New cells grow abnormaly
affected by antibiotics
Gram + or - ?
Gram +
Cells burst due to weakened cell wall - Lysis
affected by antibiotics
Gram + or - ?
Gram +
Thin peptidoglycan cell wall
Gram + or - ?
Gram -
Peptidoglycan surrounded by a thin outer membrain layer
Gram + or - ?
Gram -
Gram -
- thin peptidoglycan layer
- thin outer membrane
Antibiotic must cross cell wall to be effective
Gram + or - ?
Gram -
Ridgid cell wall to prevent exess water access
Gram + or - ?
Gram -
Cells dont burst
are not affected by antibiotics
Gram + or - ?
Gram -
Cells continue to grow
are not affected by antibiotics
Gram + or - ?
Gram -
Stains purple
Gram + or - ?
Gram +
Stains pink
Gram + or - ?
Gram -
Wich stain dosn’t effect gram - bacteria?
Crystal Violet
Why is Safranin able to stain Gram - but not Gram+?
Safranin is smaller than crystal violet and can penitrate the outer membrain layer of gram - to reach the peptidoglycan layer underneeth BUT in gram +, the darker crystal violet stain is too dark for the pink to be seen, but it dose still stain the gram +
How dose penicilin work on gram +?
- Penicilin disrupts the cell wall synthisis
- Wich stops an enzyme, that forms cross bridges, from working
- This weakens the short protines they are made of
- Leading to the cells being unable to hold up under osmosis and bursting (lysis)
Why dosn’t penicilin work on gram -?
Gram - has an outer cell memebrain that acts as a barier that protects the peptidoglycan from the penicilin.
- this keeps the cell wall strong/ridgid
- prevents the cell from bursting under osmosis
Gram staining technique
- Add b——- cultures to microscope slide
- Add C——- V—– stain and rince with lugiol’s iodeen and ethanol
- Add s——- stain and rince with water
- Allow to — and add cover slip before viewing under microscope
- Add bacterial cultures to microscope slide
- Add crystal violet stain and rince with lugiol’s iodeen and ethanol
- Add safranin stain and rince with water
- Allow to dry and add cover slip before viewing under microscope
