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Completed > Labs 6-11 > Flashcards

Labs 6-11 Flashcards

0
Q

Why is it important to prepare thin smears

A

The thickness of the smear will determine if you can visualize individual cells, their arrangement, or details regarding microstructures associated with cells

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1
Q

Name several goals in preparing a smear

A

To cause the cells to adhere, to insure that shrinkage of cells does not occur, to prepare thin smears

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2
Q

Why is it important to be sure to cool the loop completely before inserting it into a medium

A

A loop that is too hot Will spatter the medium and move bacteria into the air

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3
Q

Describe the procedure for making a bacterial smear using a liquid media

A

To loopfuls of liquid containing organisms are placed on the slide; the smear is allowed to dry at room temperature; slide is passed through flame several times to heat-kill and fix organisms to the slide

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4
Q

What is the first step in the procedure for making a bacterial smear using a solid media

A

To loopfuls of sterile distilled water are placed on the slide

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5
Q

Name three of the most commonly used dyes for simple staining

A

Methylene blue, basic fuchsin, and crystal violet

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6
Q

Why do dyes work well on bacteria

A

Because they have color bearing ions that are positively charged

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7
Q

What is another word for color bearing ions

A

Chromophores

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8
Q

What three physical characteristics can be determined by simple staining

A

Morphology, size and arrangement

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9
Q

Negative stains are _____ and thus have a ____ charged chromophore

A

Negative stains are acidic and thus have a negatively charged chromophore

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10
Q

Two examples of a negative stains

A

India ink and nigrosin

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11
Q

Negative staining can be useful for studying what and why

A

Cell dimensions because heat fixation is not performed no shrinkage of cells occurs and size determinations are more accurate

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12
Q

Three examples of when negative staining is more useful

A

Size determination, capsule observation, observing spirochetes

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13
Q

Which cell has a thicker PG layer

A

Gram-positive

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14
Q

Which cell has an outer membrane

A

Gram-negative

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15
Q

What is the primary stain in gram staining and color results

A

Crystal violet; both cells stain purple

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16
Q

What is the mordant in gram staining and color results

A

Grams iodine; both cells stain purple

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17
Q

What counterstain is used in gram staining and color results

A

Safranin; +=purple, -=pink

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18
Q

What is used for decolorization in gram staining and color results

A

Ethyl alcohol; +=purple, -= “clear”

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19
Q

Final color results of gram staining

A

Gram-positive will be purple, gram-negative will be pink

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20
Q

What significant difference in structure determines whether the dye-mordant complex is removed from the Gram-negative cell or remains associated with the gram-positive cell

A

Thickness of the PG layer that comprises the cell wall as well as the presence of an outer membrane

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21
Q

Can gram-negative bacteria ever convert to Gram-positive bacteria

A

No

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22
Q

Why is it important to prepare thin smears

A

Thin smears allow the observation of individual cells and any arrangement in which the cells occur; thickness also affects the colorization

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23
Q

What is the most critical step in the Gram stain procedure

A

Decolorization

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24
Q

What happens if the Destaining reagent is over applied

A

The dye-mordant complex can eventually be removed from gram-positive cells converting them to gram-negative cells

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25
Q

Explain the gram staining technique

A

crystal violet for 1 min; rinse with water; gram’s iodine for 1 min; rinse with ethyl alcohol 10-20 secs;rinse with water; safranin for 1 min; rinse with water; blot dry with bibulous paper

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27
Q

Describe the shape and color of B. megaterium

A

Purple Rods in a long chain (gram-positive)

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27
Q

What 3 genera of medical importance produce endospores

A

Bacillus, clostridia, sporosarcina

28
Q

Describe the shape and color of M. catarrhalis

A

Large pink diplococci

(gram-negative)

29
Q

If nutrients once again become available the endospore can go through the process of ____

A

Germination to form a new vegetative cell and growth will resume

30
Q

Describe endospores

A

Very dehydrated; not actively metabolizing; resistant to heat, radiation, acids, and many chemicals

31
Q

Why are endospores resistant

A

Exosporium (A protein coat that forms a protective barrier around the spore)

32
Q

The Schaeffer-Fulton spore stain method has four steps describe the first

A

Cover with small piece of paper towel and saturate with malachite green. Steam for 10 minutes. Add additional stain if stain boils off

33
Q

What are the functions of calcium dipicolinate and spore specific proteins during endospore formation

A

Form a cytoplasmic gel that reduces the protoplasmic volume of the endospore to a minimum

34
Q

The Schaeffer-Fulton spore stain method has four steps describe the 3rd and 4th (last)

A

Counterstain with safranin for about one minute. Rinse briefly with water to remove safranin. Blot dry with bibulous paper

35
Q

What does contraction of the thick cortex that forms around the endospore result in

A

A smaller dehydrated structure

36
Q

Is calcium dipicolinate present in vegetative cells

A

No

37
Q

Explain how to destroy endospores by heating

A

They must be exposed for 15 to 20 minutes to steam under pressure which generates temps if 121 C

38
Q

Describe the color results of a properly stained spore-former utilizing the Schaeffer Fulton method

A

A green endospore contained in a Pink sporangium

39
Q

The Schaeffer-Fulton spore stain method has four steps describe the 2nd

A

After the slide has cooled sufficiently remove the paper towel place it in the biohazard bucket and rinse the slide with water for 30 seconds

40
Q

What color are the spores on the Bacillus Megaterium slide when using the Schaeffer-Fulton spore stain method

A

Green

42
Q

The Dorner method for staining produces

A

A red spore within a colorless sporangium

43
Q

There are six steps to the Dorner method for staining. What is the 1st

A

Make a heavy suspension of bacteria by dispersing several loopfuls of bacteria in five drops of sterile water

44
Q

There are six steps to the Dorner method for staining. What is the 2nd-6th

A

Add five drops of carbolfuchsin to the bacterial suspension, Heat in a beaker of boiling water for 15 minutes; Mix several loopfuls of bacteria in a drop of nigrosin on the slide and spread across slide. allow to dry and examine.

44
Q

What to genera test positive when acid-fast staining

A

Mycobacterium and nocardia

45
Q

What color are the spores when using the Dorner method for staining

A

Red

46
Q

Mycolic acid

A

It waxy material in the cell wall that significantly affects the staining properties and prevents them from being stained by many of the stains used in mcb

47
Q

Staphylococcus aureus

A

Non-acid-fast coccus that can also be part of the normal flora of humans as well as a potential pathogen

48
Q

The acid-fast stain is an important diagnostic tool the identification of what two diseases

A

Leprosy and TB

49
Q

Describe the steps to the acid-fast staining method

A

Cover with carbolfuchsin; steam over boiling water for 5 min; cool; decolorize with acid alcohol for 15 to 20 seconds; rinse with water; methylene blue for 1 min; rinse with water; blot dry

50
Q

What is the function of a mordant

A

A chemical that fixes a dye in or on cells by forming an insoluble compound and thereby promoting retention of that dye

51
Q

Methylene blue is a positive or negative charged chromophore

A

Positively charged chromophore; basic stain

52
Q

Describe the appearance of Staphylococcus aureus when gram staining

A

Clusters, cocci, purple

(gram-positive)

53
Q

Describe the appearance of E. coli when Gram staining

A

Pink, rods, gram-negative

54
Q

What are the primary stain,counterstain, and mordant of the Schaeffer Fulton method of spore staining

A

Primary stain: malachite green; counterstain: safranin; mordant: heat

55
Q

What are the primary stain, counter stain, & mordant using the Doerner method of spore staining

A

Primary stain: carbolfuchsin; counterstain: nigrosin Mordant: heat

56
Q

Four diseases detected by spore staining and their genera

A

Anthrax (bacillus);

botulism, tetanus, gangrene all by clostridium

57
Q

What is the primary stain, counterstain, decolorizer, mordant of the acid-fast staining method

A

Primary stain: carbolfuchsin; counterstain: methylene blue; Decolorizer: acid alcohol;
Mordant: heat

58
Q

Color results of acid-fast positive

A

Red

59
Q

Color results of acid-fast negative

A

Blue

60
Q

Two genera of acid-fast positive bacteria

A

Mycobacterium & nocardia

61
Q

E. coli Gram stain and morphology

A

Negative rods

62
Q

Bacillus Megatherium Gram stain and morphology

A

Positive rod, short chains

63
Q

Staphylococcus aureus Gram stain and morphology

A

Positive cocci, irregular clusters

64
Q

Mycobacterium smegmatis Gram stain and morphology

A

Positive (purple) rods, may be Y shaped or branched

65
Q

How many micrometers is each space under 40X power

A

2.5 microns

66
Q

How many micrometers is each space under 100X power

A

1 micron

68
Q

Which is the only anionic stain

A

nigrosin

69
Q

3 genera of spore formers (of medical importance)

A

Bacillus, Clostridium, and Sporosarcina

Completed (12 decks)

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