Lab Practicum 1

Question 1

What type of stain is a background stain that is also an indirect stain?

Answer 1

Negative Stain

Question 2

What acidic dye did we use for the negative stain?

Answer 2

Nigrosin

Question 3

What stain uses basic dyes that are positively charged?

Answer 3

Simple Stain

Question 4

In a simple stain, what is the drying time for Methylene Blue? Crystal Violet? Safranin?

Answer 4

Methylene Blue: 2 minutes
Crystal Violet: 30 seconds
Safranin: 2 minutes

Question 5

What are the steps of the bacterial smear?

Answer 5

1. 1 drop of bacteria in middle of the slide
2. 1 drop of deionized water closer to the side of the
   slide
3. Mix
4. Air Dry for time depending on the dyes
5. Heat fix

Question 6

What is the procedure for a simple stain?

Answer 6

1. Bacterial Smear
2. Flood the slide with basic dye of your
   choice
3. RInse off
4. Blot dry

Question 7

What type of stain is a Gram stain?

Answer 7

a differential stain

Question 8

What are the two bacteria we used with the Gram Stain?

Answer 8

1. Escherichia Coli

2. Staphylococcus

Question 9

What are the steps for the Gram Stain?

Answer 9

1. Using Crystal violet (primary stain)- dry for
   30 sec
2. Rinse off
3. Use Gram’s Iodine (mordant)- dry for 1
   minute
4. Rinse off
5. Use 95% ethanol (decolorizing) - Dry for 30
   sec
6. Rinse off
7. Flood with Safranin (counterstain) - dry for 2
   minutes
8. Rinse off
9. Blot dry

Question 10

What type of stain is an Acid Fast Stain?

Answer 10

a differential stain

Question 11

What is a mycobacterium?

Answer 11

a mycolic acid (lipid)

Question 12

What are the two bacteria we used in the Acid Fast Stain?

Answer 12

1. Escherichia Coli

2. Mycobacterium Smegmatis

Question 13

What are the steps of the Acid Fast Stain?

Answer 13

1. bacterial smear
2. 80-85 degrees on hot plate
3. Put filter paper on top of slide glass
4. Add Carbolfuchsin to the filter paper
5. Keep wetting it for 5 Minutes
6. Peel off filter paper
7. Put inside staining tub and wait for it to cool
8. Rinse off remaining Carbolfuchsin with water
9. Flood with Acid Alcohol for 30 seconds
10. Rinse off with water then flood with methanyl Blue for 2
    minutes
11. Rinse off Methanyl Blue and blot dry

Question 14

What bacteria is used in a Spore stain?

Answer 14

Bacillus Subtilis

Question 15

What is a Spore stain?

Answer 15

an endospore stain that differentiates the spores

Question 16

What are the steps of the Spore stain?

Answer 16

1. Put on slide glass and Bacterial Smear
2. 80-85 degrees; filter paper and Malachite green for 5
   minutes
3. Peel off filter paper and put inside staining pan
4. flood with safranin for 2 minutes
5. Rinse and then blot dry

Question 17

What are the steps for a capsule stain?

Answer 17

1. Negative stain with nigrosin
2. Put in staining tub; Flood slide glass with crystal violet for 30 seconds
3. Rinse off with .85% NaCl (=saline sol)

Question 18

What are the 5 Sterilization Methods?

Answer 18

1. Autoclave (121°C for 15-20 minutes, 15 psi)
2. Dry Heat (160-170°C for 2 hours)
3. UV Radiation (260nm)
4. Filtration (.22 um)
5. Ethylene Oxide (Gas)

Question 19

What are the physical states of culture media?

Answer 19

1. Liquid(broth)- to obtain large amount of cells per unit
   medium
2. Semi-Solid: in test tube, like jello substance
3. Solid: i) to obtain pure culture ii) to observe the colony
   appearance iii) storage

Question 20

What are the ingredient types of media?

Answer 20

1. =components
2. Complex = Yeast extract, Beef extract, peptones…
3. Chemically Defined = mainly for autotrophs; various
   chemicals are examples

Question 21

https://www.microscopemaster.com/parts-of-a-compound-microscope.html

Answer 21

link for microscope parts and their functions