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BIO204 > chap 6 > Flashcards

chap 6 Flashcards

1
Q

microbial growth needs both chemical: ______ ,and physical: ______ requirements

A

chemical: carbon, nitrogen, sulfer, phosphorous, trace elements (NADH, FADH), oxygen (in organic), organic growth factor
physical:
temperature, pH

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2
Q

most common nutrients:

A

carbon, oxygen, nitrogen, hydrogen

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3
Q

microbial growth is increase in _____ of cells, not cell ___.

A

number, (not) size

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4
Q

Temperature: optimal growth temp =

A

temp at which mo grows most rapidly

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5
Q

temperature changes affect:

A
  • proteins; enzyme function (affects 3-D structure of molecule and H-bonding)
  • lipids in cell membranes: too low=rigid, fragile cell membranes (not able to osmosis and diffusion). Cholesterol prevent function in low temp.
    too high=too fluid and can’t hold in contents.
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6
Q

temperature groups based on optimal temp:

psychrophile:

A

opt. temp. between 15C and 15C, die at temps above 20C. Live in snow field, ice. not involved in human disease but in food spoilage

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7
Q

temperature groups based on optimal temp:

mesophile:

A

opt temp. btw 20C and 40C: as human pathogens

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8
Q

temperature groups based on optimal temp:

Thermophile:

A

opt temp. btw 45C and 70C: in compost piles and hot springs; no human disease, body temp is too cold

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9
Q

temperature groups based on optimal temp:

hyperthermophile:

A

(Archaea) opt temp. btw 70C and 110C

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10
Q

pH: organisms sensitive to changes in acidity; H and OH interface with H bonding in proteins and nucleic acids
- most bacteria and protozoa grow best pH 6.5-7.5 (neutral=blood):

A
  • Neureophiles = pathogens
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11
Q

pH: organisms sensitive to changes in acidity; H and OH interface with H bonding in proteins and nucleic acids
- other bacteria and fungi grow best in acidic habitats:

A
  • Acidophiles (yogurt)
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12
Q

pH: organisms sensitive to changes in acidity; H and OH interface with H bonding in proteins and nucleic acids
- ______ live in alkaline soils and water up to pH 11.5

A
  • Alkalinophiles
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13
Q

physical effects of water:

A

microbes require water to dissolve enzymes and nutrients required in metabolism

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14
Q

most cell die in absence of ______.

A

water

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15
Q

water is important reactant in many metabolic reactions

some have _______ that retain water

A

cell wall

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16
Q

_____ and ____ cease (stop) most activity in a dry environment for years

A

endospores and cysts

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17
Q

hypertonic environment (increase in salt or sugar 10%) cause_______.

A

plasmolysis = crenation of cell (shrink)

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18
Q

obligate halophiles (salt 20~30%) require high osmotic ______.

A

pressure

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19
Q

facultative halophiles (_______) tolerate high osmotic pressure

A

osmotlerant

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20
Q

chemical requirements:

carbon

A
  • organic molecules, energy source
  • chemoheterotrophs use organic carbon sources
  • autotrophs use CO2
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21
Q

chemical requirements:

nitrogen

A
  • in amino acids and proteins
  • most bacteria decompose proteins
  • some bacteria use NH4 or NO3
  • a few bacteria use N2 in nitrogen fixation
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22
Q

chemical requirements:

sulfur

A
  • in amino acids, thiamine, biotin (vitamin)
  • most bacteria decompose proteins
  • some bacteria use SO4 2 or H2S
23
Q

chemical requirements:

phosphorus

A
  • in DNA, RNA, ATP, and membranes

- PO4 3 is a source of phosphorus

24
Q

chemical requirements:

trace elements

A
  • inorganic elements required in small amounts

- usually as enzyme cofactors

25
Q

categories mo’s based on their O2 requirements:

obligate aerobes

A
  • undergo aerobic respiration. don’t ferment.
26
Q

categories mo’s based on their O2 requirements:

obligate anaerobes

A
  • do not use aerobic metabolism
27
Q

categories mo’s based on their O2 requirements:

facultative anaerobes

A
  • can maintain life via fermentation or anaerobic respiration or by aerobic respiration
  • E.coli: when O2 is not avail and nitrate (NO3) is, E.coli will use the nitrite (NO2) and ultimately ammonia (NH3) = ferment
28
Q

categories mo’s based on their O2 requirements:

microaerophiles

A
  • require small amount of O2 (2-10% oxygen) and are inhibited by normal (~21%) atmospheric amounts )eg. H.Pylori) due to limited amounts of enzymes
29
Q

categories mo’s based on their O2 requirements:

aerotolerant anaerobes / obligate fermentors

A
  • these mo’s are indifferent to oxygen because they do not use aerobic, and have some limited amounts of oxygen by-product enzymes (Streptococcus does not produce Catalase)
30
Q

toxic oxygen (Reactive Oxygen Species - ROS):

  • singlet oxygen:
  • superoxide free radicals:
  • peroxide anion:
  • hydroxyl radical
A
  • singlet oxygen = O2 boosted to a higher-energy state
  • superoxide free radicals= superoxide dismutase (enzyme)
  • peroxide anion= catalase + peroxidase = hydrogen peroxide
  • hydroxyl radical = OH
31
Q

biofilms = microbial communities
form _____ or ______
- bacteria attracted by chemicals via quorum sensing
- organism live in association with different species:

A

slime or hydrogels

  • antagonistic relationships
  • synergistic relationships
  • symbolic relationships
32
Q

culture media = depending on what you want to do.

A
  • culture medium = nutrients prepared for microbial growth
  • sterile = no living microbes
  • inoculum = (inoculated) introduction of microbes into medium
  • culture = microbes growing in/on culture medium
33
Q

Agar (red seaweed)

A
  • complex polysaccharide
  • used as solidifying agent for culture media in Petri plates, slants (sloping surface of agar in a test tube), and deeps
  • generally not metabolized by microbes
  • liquefies at 100C
  • solidifies at
34
Q

culture media

A
  • chemically defined media = exact chemical composition is known
  • complex media = extracts and digests of yeasts, meat, or plants
  • selective media
  • differential media
  • anaerobic media
35
Q

heterotrophic bacteria =

A

bacteria that rely on organic compounds to grow and reproduce.

36
Q

selective media

A
  • saboraud’s gaar (media) - lower pH (5.6); encourages the growth of fungi and not bacteria
  • thioglycolate media - contains a reducing compound which select for oxygen use
  • endo agar (not gram-) - contains the dye, basic fuschin, which selects for Gr-mo’s that is selective for Staphylococcus (osomotolerant)
37
Q

differential media

A
  • blood agar = hemolysis patterns (alpha/green, bata/clear, gamma/none/don’t secrete)
  • SIM media - sulfate and production of H2S (hydrogen sulfide) blackens media; differentiate enterics (intestine): Salmonella, Shigella, E.coli
  • endo agar = contains lactose: appears red when colonies fermented
  • mannitol/salt agar = contains phenol pH indicator : when mo’s fermented the mantel sugar and the pH becomes acidic, the agar turns from pink to yellow
38
Q
  • dark colonies =
  • white/clear colonies =
  • white + dark colonies =
A

E.coli
coliform bacteria
total coliform bacteria

39
Q

anaerobic culture method

A
  • reducing media = contains chemicals: thioglycolate or oxyrase to combine O2. Heated to drive off O2
40
Q

capnophiles

A

microbes require high CO2 condition

candle jar = 5-7% oxygen

41
Q

biosafety levels

A 
BSL1 = no special precautions
BSL2 = lab coat, gloves, eye protection
BSL3 = biosafety cabinets to prevent airborne transmission
BSL4 = sealed, negative pressure (moon suit) exhaust filter twice
42
Q

colony is a population os cells arising from a single cell or spore or from a group of attached cells
colony is ofter called ____________.
________ method is used to isolate pure cultures

A

colony-forming unit (CFU)

streak plate method

43
Q

deep-freezing =

A

-50 to -95C

44
Q

lyophilization (freeze-drying) = for many years

A

frozen (-54 to -72) and dehydrated in a vacuum

45
Q

reproduction in prokaryotes =

A
  • binary fission
  • budding
  • fragmentation of filaments
46
Q

binary fission:

20min (average time)
19-20 hours:Tuberculosis

A
  1. cell elongates and DNA is replicated. (chromosome attache to cell membrane)
  2. cell wall and plasma membrane begin to constrict
  3. it pinch together and cross-wall forms; completely separating the 2 DNA copies
  4. cells separate.
47
Q

bacterial growth curve

in culture, gram neg- are all dead phase.

A
  1. lag phase
  2. log phase
  3. stationary phase=increase waste
  4. death phase
48
Q

after incubation, count _____ on plates 25-250 (CFUs)

= viable count (not count dead one)

49
Q

SIM =

A 
Sulfate = H2S (black +)
Tryptophan = Indole (red ring +)
Motility = stab line (needle), E.coli, Salmonella, Shigella
50
Q

counting bacteria by filtration = viable count

A

filter retains cells

51
Q

most probable number = viable count

A
  • multiple tube MPN method
  • count positive tubes (count how many tubes are positive)
  • viable count
52
Q

direct microscopic count of bacteria = non viable count

A

all cells in several large squares are counted, then numbers are averaged.

53
Q

measuring microbial growth:

indirect method

A
  • turbidity = how many bacteria are in it
  • metabolic activity
  • dry weight (dry, and weigh) = Cyanobacteria: which lake has more or less
54
Q

Generation time =

A

bacteria grow in different rate under optimal condition of growth.

BIO204 (5 decks)

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