Gram staining

Question 1

What is the 1st theory to explain gram staining ?

Answer 1

Gram-Positives have a thick peptidoglycan layer (a polymer unique to bacteria). When alcohol is added the pores shrink and the crystal violet-iodine complex cannot be washed out.

Question 2

What is the 2nd theory to explain gram staining ?

Answer 2

Gram-Positives and Gram-Negatives contain different lipids in the cell wall. The lipids in Gram-Positives do not allow decolorization. Gram Negatives contain mucopolysaccharides, which allow color to be washed out.

Question 3

What is the 3rd theory to explain gram staining ?

Answer 3

Isoelectric Point (IEP): The PH of a compound where the net charge equals zero. Gram-positives have a low IEP and therefore react with the basic dye.

Question 4

What are the reagents of gram staining ?

Answer 4

• crystal violet
• grams iodine
• Ethanol
• safranin

Question 5

Crystal violet (purpose)

Answer 5

primary stain

Question 6

Iodine (purpose)

Answer 6

Mordant

Question 7

Ethanol

Answer 7

decolorizing agent

Question 8

Safranin

Answer 8

Counterstain

Question 9

Explain the gram staining process…

Answer 9

1. place quarter dot of water on the slide
2. flame the loop
3. sweep the top of the agar to acquire organism
4. swirl the organism thoroughly in the dot of water
5. sway the slide back and forth above the bunsen burner until liquid is 90% dry
6. pour crystal violet dye to cover entire dried organism and allow to sit for 1 min
7. Wash stain off with distilled water
8. Pour grams iodine and allow to sit for 1 min
9. rinse with ethanol until solvent washes off colorlessly

Question 10

What was the result of the staph gram stain ?

Answer 10

.

Question 11

What was the result of the strep gram staining ?

Answer 11

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