Lab 2

Question 1

What are the 3 transmissions of microorganisms?

Answer 1

• contact transmission (direct, indirect, droplet)
• vehicle transmission (medium of transfer, food, water, blood etc)
• vector transmission (transmitted from an animal to human via another organism ie mosquitoes or ticks)

Question 2

What are possible bacteria you would find in the mouth? (4 points)

Answer 2

• Candida albicans
• Streptococcus mitis
• Staohylococcus aureus
• Streptococcus pyogenes

Question 3

What does peptidoglycan do?

Answer 3

Provides structural support and maintains the characteristic shape of the cell

Question 4

What is the gram stain process?

Answer 4

• Make a film
• flood the film with crystal violet (methyl violet)
• leave for one minute, rinse with water
• flood with Lugol’s iodine
• leave for one minute, rinse with water
• decolorise with acetone
• 5 secs only, then rinse with water
• counterstain with red dye (carbol fuchsin)
• leave for one minute, rinse with water
• pat dry
• put on hotbox to dry before looking at it under microscope

Question 5

What does a gram stain allow?(4 points)

Answer 5

• helps identify bacteria, separates into 2 broad groups
• allows bacteria to be seen under a microscope
• shows shape so further grouping can be made
• gives an idea of how easy/hard they are to kill

Question 6

What is the process for preparing a slide for a gram stain?

Answer 6

• label slide
• turn on the Bunsen
• sterilise the inoculation ring and let cool
• put 2 drops of water into the slide
• flame loop
• take a small amount of bacteria from individualised colonies on agar
• emulsify in the water on the slide and spread it out
• flame loop
• slide goes onto hotbox or is air dried
• once dry need to fix it to the slide by passing through the Bunsen flame several times
• follow gram stain process