Lab Quiz 2: Gram Stain, Capsule Stain, and Endospore Stain (Bio 286 - Microbiology)

Question 1

Hans Christian Gram

Answer 1

developed Gram stain in 1884

Question 2

general staining technique

Answer 2

1. primary stain… 2. mordant… 3. decolorizer… 4. secondary stain

Question 3

Gram stain - primary stain

Answer 3

crystal violet (1 min)

Question 4

Gram stain - mordant

Answer 4

Gram’s iodine (1 min)

Question 5

Gram stain - decolorizer

Answer 5

acetone alcohol (5 seconds)

Question 6

Gram stain - secondary stain

Answer 6

safranin (1 min)

Question 7

appearance of gram positive cells after crystal violet in gram stain

Answer 7

purple

Question 8

appearance of gram negative cells after crystal violet in gram stain

Answer 8

purple

Question 9

appearance of gram positive cells after gram’s iodine in gram stain

Answer 9

purple

Question 10

appearance of gram negative cells after gram’s iodine in gram stain

Answer 10

purple

Question 11

appearance of gram positive cells after acetone alcohol in gram stain

Answer 11

purple

Question 12

appearance of gram negative cells after acetone alcohol in gram stain

Answer 12

colorless

Question 13

appearance of gram positive cells after safranin in gram stain

Answer 13

PURPLE

Question 14

appearance of gram negative cells after safranin in gram stain

Answer 14

PINK

Question 15

primary colorizer

Answer 15

stains everything

Question 16

mordant

Answer 16

causes primary colorizer to bind tighter

Question 17

gram positive cells appear purple in gram stain

Answer 17

because the cell wall collapses and traps the purple dye; the purple dye overpowers the pink dye from safranin to appear purple

Question 18

gram negative cells appear pink in gram stain

Answer 18

because the acetone dissolves the outer membrane so the purple dye dissipates, allowing the safranin to turn the now colorless cells pink

Question 19

variable results in gram staining

Answer 19

due to age of culture, variability in amounts of peptidoglycan layer

Question 20

difficult species to gram stain

Answer 20

spirochetes (too thin to be resolved by microscopy), mycobacterium (waxy mycolic acid layer in cell wall blocking entrance of stains), intracellular bacterial parasites (difficult to stain with analine dyes)

Question 21

proper gram stain of gram positive bacteria

Answer 21

appears purple

Question 22

proper gram stain of gram negative bacteria

Answer 22

appears pink

Question 23

staphylococcus aureus

Answer 23

gram positive staphylcocci bacteria

Question 24

klebsiella pneumoniae

Answer 24

gram negative rod bacteria

Question 25

candida albicans

Answer 25

gram positive yeast

Question 26

enterococcus faecalis

Answer 26

gram positive streptococci bacteria

Question 27

moraxella catarrhalis

Answer 27

gram negative diplococci bacteria

Question 28

bacillus cereus

Answer 28

gram positive rod bacteria

Question 29

rhodospirillum rubrum

Answer 29

gram negative spirillum bacteria

Question 30

gram stain

Answer 30

a differential stain that classifies bacteria into two groups, gram-positive and gram-negative

Question 31

glycocalyx

Answer 31

very thin and difficult to detect layer of polysaccharide

Question 32

capsule

Answer 32

very thick and robust layer of polysaccharide; assist the cell in evading phagocytosis, as well as aggregation of cells, biofilm formation, and attachment of cells to some surfaces; can be the main virulence factor of certain mucosal pathogens

Question 33

capsule stain

Answer 33

not a differential stain; a stain that does not stain the capsule but instead stains the surroundings and the cells within the capsules

Question 34

capsule stain technique

Answer 34

1. india ink drop on slide... 2. transfer a drop of water using sterilized loop... 3. transfer drop of species using sterilized loop... 4. spread/smear with another slide... 5. air dry BUT NO HEAT FIX... 6. cover slide with crystal violet for 1 minute... 6. rinse slide with water and allow to air dry

Question 35

endospore stain

Answer 35

A differential stain used to detect the presence and location of endospores in bacterial cells

Question 36

endospore

Answer 36

a spore produced within a vegetative cell under adverse conditions; can withstand chemical agents, antibiotics, heating, cold, and even some exposure to radiation

Question 37

endospore stain - primary stain

Answer 37

malachite green

Question 38

endospore stain - mordant

Answer 38

heat (steam bath) for 15 minutes

Question 39

endospore stain - decolorizer

Answer 39

water (1 min)

Question 40

endospore stain - secondary stain

Answer 40

safranin

Question 41

appearance of endospore after malachite green in endospore stain

Answer 41

colorless

Question 42

appearance of endospore after heat in endospore stain

Answer 42

green

Question 43

appearance of endospore after water in endospore stain

Answer 43

green

Question 44

appearance of endospore after safranin in endospore stain

Answer 44

GREEN

Question 45

appearance of vegetative cell after malachite green in endospore stain

Answer 45

green

Question 46

appearance of vegetative cell after heat in endospore stain

Answer 46

green

Question 47

appearance of vegetative cell after water in endospore stain

Answer 47

colorless

Question 48

appearance of vegetative cell after safranin in endospore stain

Answer 48

PINK

Question 49

growing the endospore-forming bacteria on more nutritious media

Answer 49

bacteria will have less endospore formation

Question 50

growing the endospore-forming bacteria on less nutritious media

Answer 50

bacteria will have more endospore formation