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Microbiology Lab Exams > Micro Lab Exam 1 > Flashcards

Micro Lab Exam 1 Flashcards

1
Q

How much media for a small test tube?

A

5 ml of media

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2
Q

How much media for a large test tube?

A

10 ml of media

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3
Q

How much media for a petri plate?

A

25 ml of media

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4
Q

A petri plate is a two step process. What are they?

A
  1. Media is placed in large test tube with the cap on so it can be sterilized.
  2. Once sterilized it can be stored in the test tube until it is to be transferred to the petri plate.
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5
Q

Negative Stain - what is the result?

A

cell remains clear and background is dark

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6
Q

What type of stain is Nigrosine?

A

Negative stain

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7
Q

What charge is Nigrosine stain?

A
  • (negative) Charge
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8
Q

What is the % of the following bacteria cells in the human mouth? Coccus, Bacillus & Spirochete

A

Coccus 100%
Bacillus 80%-90%
Spirochete 10%-20%

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9
Q

What is the importance of the quadrant streak plate inoculation?

A
  1. Observe bacteria colonies

2. separate a mixed culture of bacteria into separate colonies

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10
Q

What is the importance of heat fixing a smear before staining?

A
  1. Kill bacteria
  2. Adhere cells to slide
  3. Preparing cells for stain
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11
Q

What was the stain we used for the simple stain?

A

Methylene blue

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12
Q

What are the 4 simple stains listed in our lab book?

A

Crystal violet
Methylene blue
Safranin (red)
carbolfuchsin (red)

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13
Q

What is the process to do a simple stain with methylene blue?

A
  1. Mix the bacteria with distilled water on clean slide. Smear all over slide. Set aside and let dry.
  2. Place slide over sink/tray and use a couple drops of methylene blue. Let stain sit for 1 min on slide.
  3. Rinse slide with distilled water to remove excess stain.
  4. Blot excess water from slide and let dry. Can use paper towel or Bibulous paper.
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14
Q

What is the process to do a negative stain with Nigrosen?

A
  1. Use a clean slide and place a drop of Nigrosen on one end of the slide.
  2. Use a sterilized inoculating loop(we used toothpicks) and mix the bacteria with the Nigrosen for about 15 seconds.
  3. Re sterilize the loop in a flame before setting down.(throw out toothpick)
  4. Using a clean slide. touch the short end on the slide with the stain and a 45 degree angle and drag it toward the drop of stain/bacteria and create the smear.
  5. Remove and rise the second slide and allow the smeared slide with bacteria and Nigrosen air dry completely.
  6. Then view under the microscope.
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15
Q

What stain did we use for our negative stain?

A

Nigrosen

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16
Q

What stains are used for the gram stain?

A

Crystal Violet
Gram’s Iodine
95% ethanol (Alcohol)
Safranin

17
Q

What is the process to do a gram stain?

A
  1. Need a slide with a fixed smear of bacteria.
  2. Over a sink or tray cover the smear with Crystal Violet for 1 minute
  3. When minute is up rinse with distilled water.
  4. Then cover the smear with the Gram’s Iodine for 1 minute.
  5. When minute is up rinse with distilled water.
  6. Decolorize with the 95% ethanol (alcohol). Hold slide at a 45 degree angle and count to 10 then immediately rinse with distilled water.
  7. Last stain is the Safranin. Cover slide and wait for 1 minute.
  8. When minute is up rinse slide with distilled water.
  9. Finally blot slide gently with paper towels or bibulous paper.
  10. Then examine under microscope using oil immersion lens
18
Q

The process of heat fixing a smear before staining.

A
  1. Place small amount of distilled water on slide and then smear bacteria in water and cover the slide. Attach a cloth spin to the end of the slide to prevent burning of our fingers.
  2. Using a Bunsen burner place the flame high. Quickly move slide through the middle of the flame bacteria side up. test the heat of the slide on our hand/wrist. Do this a total of 3 times.
  3. Let cool and it is ready to stain.
19
Q

In doing a gram stain what is the purpose of the Crystal violet and what color will it be for G+ and G-?

A

The purpose is to stain the bacteria cells purple

G+ / Purple G- / Purple

20
Q

In doing a gram stain what is the purpose of the Gram’s Iodine and what color will it be for G+ and G-?

A

The purpose is it binds to the Crystal Violet.

G+ / Purple G- / Purple

21
Q

In doing a gram stain what is the purpose of the Alcohol and what color will it be for G+ and G-?

A

The purpose is to dissolve the LPS membrane

G+ / Purple G- / Clear

22
Q

In doing a gram stain what is the purpose of the Safranin and what color will it be for G+ and G-?

A

The purpose is it is a counter stain. It will stain G- cells.
G+ / Purple G- / Pink red

Microbiology Lab Exams (1 decks)

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