Micro Lab Practical 2

Question 1

Define diplococcus

Answer 1

When cocci shaped cells divide and remains attached after division is complete.- Same applies for diplobacilli.

Question 2

What types of cell shapes are associated with a single cell arrangement?

Answer 2

Cocci, bacilli, spirilla, spirochetes, and vibrios

Question 3

What cell shapes are associated with chain arrangements?

Answer 3

Cocci and bacilli

Question 4

What cell shapes are associated with tetrodes, cubes (sarina), and cluster (staphylo-) arrangements?

Answer 4

Cocci

Question 5

What cell shapes are associated with palisade and angular arrangements?

Answer 5

Bacilli

Question 6

Describe a tetrad

Answer 6

When a second cell division occurs in a plane that is perpendicular to the first division. ( looks like a square made of four circles)

Question 7

Describe a cube (sarina) shape arrangement

Answer 7

When a third cell division occurs that is perpendicular to the first two produces a cube shaped arrangement of eight cells. (cube made of eight circles)

Question 8

Describe staphylococcus

Answer 8

When the division plane of a coccus are irregular, a cluster of cells is produced.

Question 9

When are cellular arrangements easiest to see?

Answer 9

When the organisms are grown in broth, or observed from a direct smear.

Question 10

What are stains made of?

Answer 10

Solvent (water or ethanol) and a colored molecule (often benzene derivative) called chromogen.

Question 11

Define chromophore

Answer 11

The portion of a chromogen that gives it color. Chromogen may have multiple chromophores, each adding intensity to the color.

Question 12

Define auxochrome

Answer 12

The charged portion of the chromogen and allow it to act asa dye through ionic or covenant bonds between the chromogen and the cell.

Question 13

Define basic stains

Answer 13

When autochrome becomes positively charged as a result of picking up a hydrogen ion or losing a hydroxide ion- are attracted to negative charges on the surface of most bacterial cells.

Question 14

What are common basic stains?

Answer 14

Methylene blue, crystal violet, and safranin.

Question 15

What are basic stains used on?

Answer 15

bacterial smears that have been heat fixed.

Question 16

What does heat fixing do to bacteria?

Answer 16

Kills them, makes them adhere to the slide, and coagulates cytoplasmic proteins to make them more visible. Some cellular distortion is caused.

Question 17

Which cells are decolorized by the deodorizer in gram staining?

Answer 17

Gram negative.

Question 18

What is the primary stain in gram staining?

Answer 18

Chrystal violet

Question 19

What is the mordant in gram staining?

Answer 19

Iodine- used to enhance the crystal violet staining by forming a crystal violet-iodine complex.

Question 20

What is the counterstain in gram staining?

Answer 20

Safranin- which will stain the gram negative cells.

Question 21

How are gram negative cell walls different than gram positive cell walls?

Answer 21

Gram negative have higher lipid contentment and thinner peptidoglycan layer.

Question 22

What are capsules composed of ?

Answer 22

Mucoid polysaccharides of polypeptides that repel most stains because of their neutral charge.

Question 23

What are acid stains?

Answer 23

Congo red or nigrosin- used for staining the background while doing a capsule stain.

Question 24

What kind of stain is used to stain cells in the capsule staining process?

Answer 24

Basic stains

Question 25

What produces endospores?

Answer 25

Gram positive bacillus bacteria.

Question 26

Can endospores be made by small cells?

Answer 26

No, small cells don’t have enough room to make endospores.

Question 27

What genus of endospore forming bacteria are pathogenic?

Answer 27

Clostridium genus

Tetanus, botulism, gangrene

Question 28

In endospore staining, what is the primary stain doing?

What is the stain called?

Answer 28

Staining the endospores.

Malachite Green

Question 29

What is the counterstain doing in the endospore staining process?
What is the counterstain in endospore staining?

Answer 29

It is staining the bacterial walls.

Safranin

Question 30

Is there a deodorizing step in endospore staining?

Answer 30

No

Question 31

In capsule staining, what is the primary stain?

Answer 31

India ink

Question 32

In capsule staining, what is the counterstain?

Answer 32

Crystal violet

Question 33

In the capsule staining, what color is the cell?

Answer 33

purple

Question 34

What color is the capsule?

Answer 34

Clear

Question 35

What is the outer covering endospores made of ?

Answer 35

Keratin

Question 36

When conditions are favorable, what state do endospores take on?

Answer 36

They germinate and enter their vegetative state.