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Microbiology - Bacteria > Chapter 1: Bacterial morphology, taxonomy, and Gram stain > Flashcards

Chapter 1: Bacterial morphology, taxonomy, and Gram stain Flashcards

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Biology 101 flashcards
1
Q

What are the 4 major shapes of bacteria?

A

1) Cocci - spherical
2) Bacilli - rods (short bacilli are called coccobacilli)
3) Spiral - comma, S, or spiral-shaped
4) Pleomorphic - lacking a distinct shape, like jello

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2
Q

What are the 7(+1) classic Gram-positive bugs that cause disease in humans?

A

1) Streptococcus, 2) Enterococcus
3) Staphylococcus
4) Bacillus
5) Clostridium
6) Corynebacterium
7) Listeria
(8) Mycobacteria (weakly Gram+)

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3
Q

What is the morphology of the classic Gram-positive bacteria? (hint: how do you remember the classification)

A

Of the Gram-positives, 3 are cocci and 4(+1) are rods. 2 are branching filamentous growth

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4
Q

What Gram-positive bacteria are cocci? (3)

A

1) Streptococcus
(2) Enterococcus
3) Staphlococcus

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5
Q

What Gram-positive bacteria are bacilli? (4+1)

A

1) Bacillus
2) Clostridium
3) Corynebacterium
4) Listeria
(5) Mycobacteria (weakly Gram+)

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6
Q

Which Gram-positive bacilli form spores? (2)

A

1) Bacillus

2) Clostridium

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7
Q

Which Gram-positive bacilli do not form spores? (2+1)

A

1) Corynebacterium
2) Listeria
(3) Mycobacteria

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8
Q

What is the morphology of Streptococcus?

A

Gram-positive cocci that form strips

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9
Q

What is the morphology of Enterococcus?

A

Gram-positive cocci that form strips

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10
Q

What is the morphology of Staphylococcus?

A

Gram-positive cocci that form clusters

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11
Q

What is the morphology of Bacillus?

A

Gram-positive rods that form spores

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12
Q

What is the morphology of Clostridium?

A

Gram-positive rods that form spores

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13
Q

What is the morphology of Corynebacterium?

A

Gram-positive rods

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14
Q

What is the morphology of Listeria?

A

Gram-positive rods

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15
Q

Which bacteria is weakly Gram-positive?

A

Mycobacteria

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16
Q

Mycobacteria are weakly Gram-positive. What is a better stain for mycobacteria?

A

Acid-fast stain

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17
Q

Acid-fast stain detects which bacteria? Why is it needed?

A

Mycobacteria, which is weakly Gram-positive.

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18
Q

What Gram-negative bacteria are cocci? (2)

A

1) Neisseria2) Moraxella

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19
Q

What Gram-negative bacteria are spirals? (1)

A

Spirochetes

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20
Q

Which bacteria are the spirochetes? (3)

A

1) Borrelia (Giemsa)
2) Leptospira
3) Treponema

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21
Q

What is the morphology of Neisseria?

A

Gram-negative diplococci

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22
Q

What is the morphology of Moraxella?

A

Gram-negative diplococci

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23
Q

What is the morphology of spirochetes?

A

Gram-negative spirals

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24
Q

Can spirochetes be detected by Gram-stain? Why or why not?

A

Spirochetes have a gram-negative cell wall but are too small to be seen with the light microscope.

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25
Q

How can you detect spirochetes?

A

Spirochetes must be visualized with a special darkfield microscope.Spirochetes have a Gram-negative cell wall but are too small to be seen with the light microscope.

26
Q

Which bacteria is neither Gram-negative nor Gram-positive so does not Gram-stain? Why not?

A

Mycoplasma lack a cell wall, so they are neither Gram-positive nor Gram-negative.

27
Q

What is the morphology of the Gram-negative bacteria? (hint: how do you remember the classification)

A

Of the Gram-negatives, 2 are cocci, 1 are spirals, 2 are pleomorphic, and the rest are rods.

28
Q

Which Gram-negative bacteria are pleomorphic? (2)

A

1) Chlamydia (Giemsa)

2) Rickettsiae (Giemsa)

29
Q

What is the morphology of mycoplasma?

A

Neither Gram-positive nor Gram-negative because they lack a cell wall.

30
Q

What structure is composed of small circles of double-stranded DNA adjacent to bacterial DNA?

A

plasmid

31
Q

What is bacterial DNA?

A

single circle of double-stranded DNA

32
Q

What is the mechanism of action of erythromycin?

A

antibiotic that inhibits bacterial protein synthesis at the 50S subunit of the ribosome

33
Q

What is the mechanism of action of tetracycline?

A

antibiotic that inhibits bacterial protein synthesis at the 30S subunit of the ribosome

34
Q

What antibiotic inhibits bacterial protein synthesis at the 30S subunit of the ribosome?

A

tetracycline

35
Q

What antibiotic inhibits bacterial protein synthesis at the 50S subunit of the ribosome?

A

erythromycin

36
Q

Which bacteria do not Gram stain well? (6)

A

These Microbes May Lack Real Color

1) Treponema
2) Mycobacteria
3) Mycoplasma
4) Legionella
5) Rickettsia
6) Chlamydia

37
Q

Why doesn’t Treponema Gram stain well?

A

it is a spirochete and too thin to be visualized

38
Q

Why doesn’t mycobacteria Gram stain well?

A

high lipid content in cell wall

39
Q

Treponema doesn’t Gram stain well. What is a better way to detect treponema? (2)

A

Darkfield microscopyFluorescent antibody staining

40
Q

Mycobacteria doesn’t Gram stain well. What is a better way to detect mycobacteria?

A

Acid-fast stain : the carbolfuchsin detects the high lipid content in the cell wall

41
Q

Why doesn’t mycoplasma Gram stain well?

A

It lacks a cell wall.

42
Q

Why doesn’t Legionella Gram stain well?

A

It is predominantly intracellular.

43
Q

Legionella doesn’t Gram stain well. What is a better way to detect Legionella?

A

silver stain

44
Q

What bacteria can be detected by acid-fast stain?

A

Mycobacteria(and weakly Nocardia)

45
Q

What bacteria can be detected by dark-field microscopy?

A

Treponemes (spirochetes)

46
Q

What bacteria can be detected by silver stain?

A

Legionella

47
Q

Why doesn’t Rickettsia Gram stain well?

A

it’s an intracellular parasite

48
Q

Why doesn’t Chlamydia Gram stain well?

A

It’s an intracellular parasite, and lacks muramic acid in its cell wall

49
Q

Which Gram-positive bacteria have morphology of branching filamentous growth? (2)

A

1) Actinomyces (anaerobic)

2) Nocardia (weakly acid-fast)

50
Q

What is the morphology of Actinomyces?

A

Gram-positive branching filamentous growth

51
Q

What is the morphology of Nocardia?

A

Gram-positive (acid-fast)

52
Q

Which bacteria have unusual cell membranes and cell walls? (3)

A

1) Mycoplasma
2) Mycobacteria
3) Chlamydia

53
Q

What is unusual about the cell membrane of mycoplasma?

A

Mycoplasma cell membrane contain sterols

54
Q

The cell membrane of which bacteria contains sterols?

A

Mycoplasma

55
Q

The cell wall of which bacteria lacks muramic acid and is therefore not sensitive to penicillin?

A

Chlamydia

56
Q

Which bacteria lacks a cell wall?

A

Mycoplasma

57
Q

What is unusual about the cell wall of mycoplasma?

A

Mycoplasma doesn’t have a cell wall.

58
Q

What is unusual about the cell membrane of mycobacteria?

A

It contains mycolic acid

59
Q

What bacteria contain mycolic acid in their cell membrane?

A

Mycobacteria

60
Q

What is unusual about the cell wall of mycobacteria?

A

high lipid content

61
Q

Which bacteria have a high lipid content in their cell wall and thus need to be detected by acid fast stain?

A

Mycobacteria

Microbiology - Bacteria (15 decks)

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