Gram Staining

Question 1

primary dye

Answer 1

crystal violet

Question 2

mordant (binding agent)

Answer 2

iodine

Question 3

decolorizer

Answer 3

95% ethanol

Question 4

secondary/counter stain

Answer 4

safranin

Question 5

gram-negative cell

Answer 5

pink (THIN peptidoglycan layer); NO teichoic acid

Question 6

gram-positive cell color

Answer 6

purple (THICK peptidoglycan layer; YES teichoic acid

Question 7

Lipid A is found in what type of cell?

Answer 7

gram-negative

Question 8

teichoic acid is found in what type of cell?

Answer 8

gram-positive

Question 9

forgetting to use decolorizer causes what?

Answer 9

false positive; gram-negative cells will stain purple and appear to be gram-positive

Question 10

too long of exposure to decolorizer causes what?

Answer 10

false negative; gram-positive cells will stain pink and appear to be gram-negative because they have been “bleached”