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Microbiology > Bacteria - General info > Flashcards

Bacteria - General info Flashcards

classification and structure

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1
Q

What kingdom do bacteria belong to?

A

Monera

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2
Q

Describe a prokaryote.

A

a single celled organism without a nucleus, endoplasmic reticulum, and mitochondria

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3
Q

Describe a eukaryote.

A

a multicellular organism with a nucleus with membrane, an endoplasmic reticulum, and mitochondria

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4
Q

What types of ribosomes do prokaryotes have?

A

30S +50S = 70S

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5
Q

What types of ribosomes do eukaryotes have?

A

40S + 60S = 80S

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6
Q

What are serotypes or serovars differentiated on?

A

the bases of their antigens

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7
Q

What are biotypes and biovars differentiated on?

A

the basis of some type of biological difference

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8
Q

What is is the criteria for classification of bacteria?

A

morphology, staining, cell arrangement, capsules, physiologic or biochemical properties, antigenic composition, and DNA homology

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9
Q

What is DNA homology used for?

A

it is used to determine the relationships between relatively closely related organisms

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10
Q

What percentage of same homology makes species the same?

A

70%

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11
Q

What is 16S rRNA homology used for?

A

it is used to determine relationshps between very diverse groups of organisms

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12
Q

What is MALDI-TOF-MS?

A

Matrix Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry

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13
Q

What does MALDI-TOF-MS measure?

A

it measures highly abundant, relatively small proteins in microorganisms

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14
Q

How is nuclear material kept in bacteria?

A

since there is no nuclear membrane, DNA may be attached to the cell membrane

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15
Q

What are plasmids important for?

A

the transfer of antimicrobial resistance, virulence factors, and may encode for important bacterial antigens

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16
Q

What are bacteriophages?

A

viruses that attack bacteria

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17
Q

How do bacteriophages work?

A

they insert their DNA into the bacterial DNA for purposes of replication and may lyse or may just replicate along with it

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18
Q

What do ribosomes in bacteria serve as?

A

they are attack sites for several antibodies such as tetracycline and gentamicin

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19
Q

What is the structure of the bacterial cell membrane?

A

typical lipid bilayer

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20
Q

What are the components of the cell wall in a gram positive organism?

A

capsule, a thick peptidoglycan layer, periplasmic space and the cell membrane

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21
Q

What are the components of the cell wall in a gram negative organism?

A

capsule, outer cell membrane, thin peptidoglycan layer, periplasmic space, and inner cell membrane

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22
Q

Draw the basic peptidoglycan structure of a gram positive bacteria.

A

it should look like this

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23
Q

Draw the basic peptidoglycan structure of a gram negative bacteria.

A

it should look like this.

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24
Q

What is cross-bridging of the peptidoglycan layer catalyzed by in gram positive organisms?

A

transpeptidase

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25
Q

What do antimicrobials attack in regards to the peptidoglycan layer?

A

transpeptidase to prevent cross-bridging from occuring

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26
Q

What does lysozyme do to peptidoglycan ?

A

it breaks the Beta-1, 4 linkage and lyses the peptidoglycan; this occurs in gram positive bacteria but not gram negative bacteria

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27
Q

What is the penultimate residue in S. aureus?

A

L-lysine

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28
Q

What is the penultimate residue in E. coli and other gram negatives?

A

diaminopimelic acid (DAP)

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29
Q

How does cross linking differ between the peptidoglycan layer in gram positives vs. gram negatives?

A

only 30-70% of the NAM is cross-linked making it weaker

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30
Q

What is the purpose of the peptidoglycan layer?

A

it is antigenic, protects the cell from the environment, increases the resistance of the host to infectious agents, and activates B-cells and stimulates macrophages to produce IL1, toxic effects, and adjuvant effects (MDP)

31
Q

What is the role of MDP?

A

it causes an increase in body temp and has somnogenic effects

32
Q

What are teichoic acids and what is their role?

A

polyribitol and polyglycerol phosphates, attach to NAM, is important in phage attachment and regulation of cell growth, and provide rigidity to the cell wall

33
Q

Which bacteria are techoic acids found in?

A

gram positives only

34
Q

What are lipoteichoic acids attached to and what is their purpose?

A

they are attached to the glycolipid in the cell membrane and may serve as an anchor for the peptidoglycan

35
Q

What is the structure of lipoteichoic acids and how are they excreted?

A

they are amphiphiles (have both hydrophilic and hydrophobic regions) and are excreted as vesicles

36
Q

Draw the structure of lipoteichoic acid.

A

it should look like this

37
Q

What is lipoteichoic acid similar in shape to?

A

LPS

38
Q

What does lipoteichoic acid do?

A

it induces IL6 and IL10 production in monocytes and stimulates nitric oxide release from macrophages

39
Q

Where is the lipoprotein located on gram negative bacteria and what is its role?

A

it extends into the outer membrane and serves to anchor the outer membrane on the cell

40
Q

What is different about the structure of the outer membrane in enteric gram negative bacteria from other gram negative bacteria?

A

the phospholipid is confined to the inner leaflet of the outer membrane in enteric gram-negative bacteria

41
Q

What is needed to transport larger molecules through the outer membrane of gram negative bacteria and why?

A

the outer membrane functions as a coarse molecular sieve so specific transport proteins are needed to transport molecules >800 MW

42
Q

What do porin proteins do?

A

form pores or diffusion channels for small hydrophilic molecules

43
Q

What is the structure of porins?

A

it is made up of three proteins which in turn are composed of 19 transmembrane beta sheet peptides that form a large channel in each of the porin trimers

44
Q

What does the outer membrane contain membranes for?

A

bacteriophages

45
Q

What is the role of the outer membrane?

A

it releases vesicular blebs of LPS and protein that may have a secretory function and shields from lysozyme

46
Q

What does the outer membrane of gram negative bacteria contain?

A

surface antigens, proteases, other enzymes, and virulence factors/toxins

47
Q

What is the outer membrane of gram negative bacteria less permeable to?

A

hydrophobic and amphipathic molecules except for detergents, enzymes, chemicals, and macromolecules

48
Q

What is the integrity of the outer membrane of gram negative bacteria disrupted by?

A

exposure to EDTA which removes divalent metal ions, LPS, and protein

49
Q

What is LPS?

A

an endotoxin

50
Q

What is the toxic portion of LPS?

A

Lipid A

51
Q

When are lipooligosaccharides formed?

A

when the O-Ag portion is not produced in LPS

52
Q

What do bacteria that have a complete O-Ag polysaccharide look like on an agar plate?

A

they look visually smooth

53
Q

What do bacteria that lack a an O-Ag portion look like on an agar plate?

A

they look rough in appearance

54
Q

What does the inner core of LPS contain?

A

2-keto-3-deoxy-octulosonic acid (KDO) that is unique to gram negatives and plant cell walls

55
Q

What does KDO do?

A

it binds to lipid A and helps stabilize OM

56
Q

What is the structure of flagella?

A

thin, several times the length of the cell composed of flagellin (protein) filaments

57
Q

How do flagella move?

A

motion by rotation

58
Q

Define peritrichous.

A

having flagella all over its surface

59
Q

Define polar flagellation,

A

one or more flagella rising from either of the poles of the cell

60
Q

What are periplasmic flagella?

A

flagella that are within a sheath in the periplasmic space

61
Q

What antigen is associated with flagella?

A

H antigen

62
Q

What is flagella’s role in virulence?

A

chemotaxis

63
Q

What is the structure of fili or fimbriae?

A

they are shorter and thinner than flagella and composed of pilin and fimbrin

64
Q

What antigen is associated with fili or fimbriae?

A

F antigen

65
Q

What is the role of fili or fimbriae?

A

they serve roles as receptors and adherence to other cell tupes

66
Q

What are almost all capsules composed of?

A

exopolysaccharides

67
Q

Are most bacteria capsules hard or slimy?

A

slimy

68
Q

In the bacillus species, what are capsules?

A

polypeptides

69
Q

In Klibsiella and Rhodococcus species what is the structure of capsules?

A

thick

70
Q

In regards to being antigenic, are capsules highly or poorly antigenic?

A

they can be highly antigenic but are most often poorly antigenic

71
Q

What are some functions of the capsule?

A

antiphagocytic and masks other cell organisms

72
Q

How does the capsule aid in survival in regards to phacocytosis?

A

some use the capsule to form microcolonies - phagocytic cells cannot ingest and kill a whole colony

73
Q

What are spores resistant to?

A

drying, heat, disinfectants, and antibiotics

74
Q

What enhances the germination of spores?

A

aging, heat, damage to the coat, and the presence of adequate moisture

Microbiology (50 decks)

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