Lab 3- Bacterial Smear Preparation and Simple Staining

Question 1

Why do we stain bacteria?

Answer 1

increase contrast [to make them more visible]

Question 2

Why do we heat fix organisms to slides?

Answer 2

prevents specimen from washing off the slide
inactivates any enzymes
kills the organism

Question 3

steps for heat fixing

Answer 3

1) smear cells onto slides
2) air dry
3) pass through bunsen burner flame 2-3 times

Question 4

Methylene blue is an example of a ____________

Answer 4

direct stain

Question 5

Explain the whole steps for a simple bacterial smear prep

Answer 5

1. place a small drop of water on a clean microscope slide
2. with the inoculating loop, aseptically add bacterial culture to the drop of water
   3 mix the bacterial with water to fine a suspension, and spread it out.
   4 all to air dry
   5 heat fix by sliding the slide over the fire

Question 6

Explain the procedure for simple staining of bacterial smears

Answer 6

1. cover prepared smear with stain (crystol violet)
   2 let sit for 1 min
   3 rinse slide through water
   4 gently blot dry and observe