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NYCC Microbiology > Bacterial Morphology > Flashcards

Bacterial Morphology Flashcards

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Biology 101 flashcards
1
Q

name the 3 basic bacterial shapes

A

coccus
bacillus
spirillum

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2
Q

thickness of gram-positive cell walls

A

thick

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3
Q

thickness of gram-negative cell walls

A

thin

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4
Q

why should antibiotics be avoided when treating gram-negative bacteria?

A

would release lipid A endotoxin when cell dies

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5
Q

all gram positive cell walls contain ____

A

teichoic acid (stabilizer)

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6
Q

what are the primary components of bacterial cell walls?

A

peptidoglycans: proteins & sugars

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7
Q

in bacterial cell walls, repeating units of ____ are held together by ____

A

sugars
peptide chains

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8
Q

gram negative cell walls contain the endotoxin ____

A

lipid A

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9
Q

what does teichoic acid do to the cell?

A
  • protrudes above cell wall thus imparting negative charge to cell (like rebar in concrete)
  • positive charge allows for stronger bonding with stains which are negatively charged
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10
Q

M protein is only required for infection by ____ species

A

streptococcus

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11
Q

function of M protein

A
  • protrudes from cell wall making cell too large to phagocytize
  • highly susceptible to mutation
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12
Q

mycolic acid is only found in gram _____ cell walls of _____ species

A

positive
mycobacterium

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13
Q

what is mycolic acid and its function?

A
  • waxy lipid inside cell wall structure
  • barrier against antibiotics & host defenses
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14
Q

what makes up the unique outer later of gram negative cell walls?

A

lipopolysaccharide

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15
Q

what are O polysaccharides used as?

A

diagnostic marker in gram negative wall
(E. coli O157:H7)

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16
Q

what is gram stain?

A

differential stain based on components of the bacterial cell wall

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17
Q

gram positive stains ____, while gram negative stains ____

A

purple
red/pink

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18
Q

describe the 4 steps of the gram stain procedure

A
  1. apply crystal violet (1 min), drain, rinse
  2. add grams iodine (1 min), drain, rinse
  3. decolorize w alcohol, (1 short rinse), wash immediately w water
  4. apply safranin (1 min), drain, rinse, blot
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19
Q

what are the components of the gram stain?

A
  • primary stain: crystal violet
  • mordant: gram’s iodide
  • decolorizer: 95% ethanol
  • secondary stain: safranin
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20
Q

name 7 bacterial structures

A

glycocalyx
fimbraie
pili
flagella
axial filaments
plasmids
endospores

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21
Q

many organisms are not infectious without a ____

A

capsule

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22
Q

a capsule inhibits ____

A

phagocytosis

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23
Q

glycocalyx: slime layer

A
  • associated w dental decay
  • very loose adherence to surface
  • genes are transferrable
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24
Q

fimbraie

A
  • sticky projections for adherence (like velcro)
  • found on gram neg organisms
  • genes are transferrable
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25
Q

pili

A
  • bacterial conjugation
  • motility through twitching
  • involved in development of biofilms
26
Q

flagella

A
  • motility
  • movement from one area of body to another (e. coli to bladder)
27
Q

name 4 flagellar arrangements

A
  • monotrichous
  • amphitrichous
  • lophotrichous
  • peritrichous
28
Q

what type of flagellar arrangement has one flagella at one end and allows movement in one direction, with inability to turn around?

A

monotrichous

29
Q

what type of flagellar arrangement allows movement in a rolling pattern, typically in liquids where currents can be used?

A

amphitrichous

30
Q

what type of flagellar arrangement has several flagella at one end and allows movement in one direction?

A

lophotrichous

31
Q

what type of flagellar arrangement has flagella all along the periphery, allowing movement in any direction by running and tumbling, giving it the ability to turn around?

A

peritrichous (best flagellar arrangement)

32
Q

describe the characteristics of axial filaments

A
  • endoflagella (located inside bacteria)
  • rotate like corkscrew (found in spirochetes)
  • ability to bore through tissue
  • very slow moving (latent diseases not recognized by immune system for years)
33
Q

clinical significance of flagella and axial filaments

A
  • opportunistic infections (normal flora, wrong place)
  • escape from host defenses (out run neutrophils)
  • systemic infection (into bloodstream to rest of body)
34
Q

describe the characteristics of plasmids

A
  • extra-chromosomal pieces of DNA (DNA “doughnuts”; not within nucleus)
  • carry genes for toxins and antibiotic resistance
  • transferred via pili during conjugation
35
Q

describe the factors for endospore formation

A
  • response to environmental stress (too hot/cold/wet/etc)
  • only soil-dwelling gram positive rods have ability to form spores
  • extremely resistant to heat, desiccation, toxic chemicals, UV radiation, and antibiotics
36
Q

name 3 examples of spore formers

A
  • clostridium tetani (tetanus)
  • clostridium botulinum (nerve block)
  • bacillus anthracis (anthrax: natural in skin & GI, lab-made bioweapon in pulmonary form)
37
Q

what are the 2 major categories of bacterial growth requirements?

A

physical
chemical

38
Q

physical requirements of bacterial growth

A
  • temperature (~37*)
  • pH (acidic foods)
  • osmotic pressure
39
Q

what does increased temperature do to bacterial growth?

A

breaks chemical bonds

40
Q

human pathogens fall into the ____ temperature range

A

mesophile (moderate)
(33-37*C)

41
Q

majority of bacteria grow best at what pH?

A

neutral (7.0)

42
Q

pathogens prefer the pH of ____

A

blood (7.34, slightly alkaline)

43
Q

what effect does alkaline or acidic pH have on bacterial growth?

A

break bonds thus altering protein structure = lethal event

44
Q

what is the major agent of osmotic pressure for bacterial growth?

A

water
(pressure exerted on bacteria by environment)

45
Q

high salt concentrations create a ____ environment leading to ____

A

hypertonic
plasmolysis

46
Q

obligate halophilic bacteria

A

requires high salt concentration

47
Q

extreme halophilic bacteria

A

requires very high levels of salt

48
Q

facultative halophilic bacteria

A

can grow with or without salt in the environment

49
Q

name 2 types of bacteria that can grow in the presence of oxygen

A
  • aerobes (require O2)
  • facultative anaerobes (with or without O2)
50
Q

obligate aerobes

A

must have O2

51
Q

obligate anaerobes

A

die in presence of O2

52
Q

facultative anaerobes

A

grow with or without O2

53
Q

definition of bacterial generation

A

each division of a bacteria

54
Q

binary fission

A

process whereby bacteria increase their numbers by splitting

55
Q

the time between bacterial divisions is the ____

A

generation time

56
Q

lag phase

A

entry: bacteria are adjusting to their environment

57
Q

log phase

A
  • bacteria double exponentially
  • constant minimum doubling time
  • lasts until resources depleted
  • most metabolically active
58
Q

during which phase are bacteria most susceptible to antibiotics?

A

log phase
(preoccupied with division)

59
Q

stationary phase

A
  • number of cells dividing equals number of cells dying
  • caused by decreasing availability of resources
60
Q

death phase is also known as ____

A

logarithmic decline phase

61
Q

death phase

A
  • continuous decline in number of dividing cells
  • caused by exhaustion of resources
  • cause by toxicity of environment

NYCC Microbiology (17 decks)

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