Lect 2 General Que.

Question 1

Give examples of “differential staining”

Answer 1

• Gram stain (+ve purple/ -ve pink)
• Acid fast
• Capsule stain
• Flagella stain
• Endospore stain

Question 2

Explain results of Gram staining

Answer 2

Purple = Gram positive
Thicker peptidoglycan layer → traps the crystal violet stain even after decolourization → more stain retained → purple

Pink = Gram negative
Thinner peptidoglycan layer + outer membrane → allows the crystal violet stain to wash out during decolourization → less/no stain retained → pink

Question 3

Name cocci & bacilli in pairs/ chains/ clusters

Answer 3

• Diplococci/ Diplobacilli
• Streptococci/ Streptobacilli
• Staphylococci

Question 4

What does “clear zone” in the blood agar test mean?

Answer 4

Hemolysis (breakdown of RBC)

Question 5

What does a “yellow” result in the Mannitol (sugar) test mean?

Answer 5

Fermentation of sugar (feature of pathogenetic strain) produce acids as a byproduct that lowers the pH and turns the red medium to yellow

Question 6

⭐What are the 5 steps to be considered when making antimibrobial agents?
(of animal virus multiplication)

Answer 6

1. ATTACHMENT of virus to host cell 附著
   => block viral receptor
2. ENTRY of viral nucleocapsid 侵入
   => block fusion process
3. SYNTHESIS of viral proteins and nucleic acids 幹活
   => interfere with the process
4. ASSEMBLY of virion (infectious form of a virus) 組裝
   => interfere with the process
5. RELEASE of progeny virions 放出後代
   => block release

Question 7

⭐What are some targets that antibiotics have but antivirals don’t?

Answer 7

Blocking vital (必要的) metabolic processes in bacteria
- inhibit enzymes in cell wall & cell membrane synthesis
- inferring (推斷) DNA and protein production