Lab 2

Question 1

Colony morphology

Answer 1

Characteristic of a colony (size, shape, color, texture) that differs based on species..

Question 2

Define colony

Answer 2

Cluster of bacteria cells growing on solid media (individual cells).

Question 3

Define Lawn

Answer 3

Complete growth of bacteria with no present individual colonies.

Question 4

What is a margin?

Answer 4

A shape of the edge of the colony.

Question 5

What is the difference between bacterial and fungal colonies?

Answer 5

Bacterial colonies are usually small with defined margins whereas fungal colonies are usually large with a fuzzy or powdery appearance.

Question 6

What is the purpose of streak plate?

Answer 6

To isolate bacterial colonies to obtain a pure culture.

Question 7

What zone do you expect most and least colonies?

Answer 7

Zone 1 will have the highest concentration and Zone 4 and 5 will have the lowest concentration of colonies.

Question 8

Why do you flame your loop before streaking the next zone on the plate?

Answer 8

We flame the loop before streaking the next zone to prevent contamination and reduce the number of bacteria on the plate.

Question 9

What is used to view endospores produced by gram positive bacteria?

Answer 9

Spore stain (differential stain)

Question 10

Gram positive bacteria have what?

Answer 10

Have thick cell wall and retain the crystal violet (staphylococcus aureus).

Question 11

Gram negative have what?

Answer 11

Have thin cell wall and don’t retain the crystal violet-iodine complex and are stained pink (Escherichia coli).

Question 12

In gram stain what is the primary stain?

Answer 12

Crystal violet

Question 13

In gram stain what is the secondary stain?

Answer 13

Safranin

Question 14

In gram stain what is the mordant

Answer 14

Iodine- helps to fix the stain.

Question 15

In gram stain what is the Decolorizer?

Answer 15

Ethyl alcohol (removes stain that is not fixed).

Question 16

What is simple stain?

Answer 16

Uses only one staining dye to visualize cells with single color.

Question 17

What is differential stain?

Answer 17

Uses two or more staining dyes to visualize cells with more than one color (primary stain/secondary stain)

Question 18

What are examples of simple stain?

Answer 18

basic dye (crystal violet, safranin, methylene blue)

Question 19

What are examples of differential stain?

Answer 19

acidic dye (spore stain, capsule stain, and acid-fast stain)

Question 20

Gram-positive bacteria produce endospores under adverse conditions, True or False?

Answer 20

True.

Question 21

what stain are used for spore stain?

Answer 21

Malachite green (primary stain) is driven into the spore utilizing heat.
Safranin (secondary stain) is used to stain the vegetative cell.

Question 22

What are capsules?

Answer 22

Extracellular structures produced by bacteria that allows them to adhere to surfaces.

Question 23

Stains used and their purpose (capsule stain)?

Answer 23

Nigrosin (primary stain) and acidic dye that is used to stain the capsule background.
Safranin (secondary stain) is used to penetrates the capsule and stains the cell surface/bacteria.

Question 24

What is the purpose and function of bacterial capsule?

Question 25

Acid fast are red/pink, non-acid fast stain blue. What stains are used in the process resulting the different outcomes?

Answer 25

Carbol funchsin: purple (primary stain)
Methylene blue (secondary stain)
Acid alcohol (decolorizer)

Question 26

What is used for bacteria containing waxy lipids (Mycolic acids) in their cell wall?

Answer 26

Mycobacterium