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MCB LEC > Module 4.2 > Flashcards

Module 4.2 Flashcards

1
Q

What is the pH range of each classification of organisms based on pH?

A

Acidophiles < pH 5.4
Neutrophiles pH 5.4 - 8.5
Alkaliphiles pH 7.5 - 11.5

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2
Q

are acid-loving organisms.

< pH 5.4

A

Acidophiles

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3
Q

acidophiles

(pH 6)
(pH 2 or less)
(pH <4) sulfur-oxidizing bacteria
(negative pH values) archaea

A

Lactobacillus
Helicobacter pylori
Acidithiobacillus
Sulfolobus and Thermoplasma, Picrophilus

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4
Q

pH 5.4 - 8.5

most human disease-causing bacteria (human blood and tissues pH = 7.2 – 7.4)

protozoans and most bacteria (pH 6.5-7.5)

A

neutrophiles

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5
Q

neutrophiles

bacteria in gut
protozoan in human large intestines
bacteria on tissue surface
skin infection

A
  • E. coli
  • Balantidium coli
  • Salmonella
  • Staphylococcus
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6
Q

 base-loving organisms
 live in soda lakes, high-carbonate soils
pH 7.5 - 11.5

A

alkaliphiles

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7
Q

pH 7.5 - 11.5

Bacillus
Vibrio cholerae (pH 9),
Alcaligenes faecalis (>pH 9),
Agrobacterium (pH 12)

A

Alkaliphiles

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8
Q

three critical temperatures (affecting enzyme
function) or cardinal temperatures:

A

minimum growth temperature
optimum growth temperature
maximum growth temperature

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9
Q

Temperature Classes of Microorganisms

A

Psychrophiles: <0 to 20, 15
Mesophiles 10 to 48, 37
Thermophiles 40 to 72, 60
Hyperthermophiles 65 to 110, 80

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10
Q

Psychrophiles

obligate psychrophiles <20 ̊C
acultative psychrophiles
snow alga

A

Sporosarcina globispora
Xanthomonas pharmicola
Chlamydomonas nivalis

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11
Q

Psychrophiles

that is present in raw milk and a variety of process meat,
can grow even in cold temp of refrigerator (can multiply at -4.4 ̊C),
can be killed by cooking and pasteurization

A

Listeria monocytogenes

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12
Q

Mesophiles

thermoduric microorganisms

A

Bacillus, Micrococcus, Lactococci, Corynebacterium

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13
Q

obligate thermophiles
facultative thermophiles

A

Geobacillus stearothermophilus
Bacillus coagulans (35-50 ̊C), B. licheniformis

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14
Q

examples of _________:

archaeobacteria (deep-sea vents, 115 ̊C)
Pyrolobus fumarii (“firelobe of the chimney”) – (113 ̊C)
Thermus aquaticus

A

Hyperthermophiles

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15
Q

Preventing Growth Using Temperature:

A

refrigeration (4 ̊C) - refrigerator
long-time storage (-30 ̊C) - ultra-low freezer
high temperatures - pressure cooker

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16
Q

Tolerating Low and High Temperatures

 unsaturated (polyunsaturated) fatty acids in phospholipids
 with enzymes functional at low temperatures
 active transport occurs well at low temperatures

A

Psychrophiles

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17
Q

Tolerating Low and High Temperatures

 saturated fatty acids in phospholipids
 heat-stable proteins and enzymes

A

thermophiles

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18
Q

Tolerating Low and High Temperatures

 no fatty acids in their membrane (phytane)
 lipid monolayer
- in some species, the opposing phospholipid tails are joined into a single tail, forming a monolayer that _______ the membrane at high temperatures

A

Hyperthermophiles,

stabilizes

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19
Q

microorganisms can be classified as (based on oxygen chuchu)

A

obligate aerobes - Pseudomonas
obligate anaerobes - Bacteroides, Clostridium methanogens
microaerophiles - Treponema pallidum
facultative anaerobes - Staphylococcus and E. coli
aerotolerant respiration - Lactobacillus (captures energy by fermentation)

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20
Q

molecule which is the reason why oxygen toxic to
some microorganisms

A

superoxide

21
Q

Anaerobic Culture Methods (How) (5)

A
  1. Use reducing media, containing chemicals that combine with O2
  2. Use anaerobic jar (GasPak)
  3. Novel method in clinical labs: Add oxyrase to growth media (OxyPlate)
  4. Work in a glove box
  5. Use candle jars
22
Q

essential ingredient of bacterial protoplasm.

is needed by actively metabolizing cells

A

Water

23
Q

Effect of drying varies:

  1. Treponema pallidum –
  2. Staphylococcus sp. –
  3. endospore-former bacteria and xerophiles –
A
  1. highly sensitive
  2. can stand for months
  3. resistant to desiccation
24
Q

– minimum pressure needed to be applied to a solution to prevent the flow of water across a semi-permeable membrane

A

osmotic pressure

25
Q

environment/osmotic solution for optimum growth

A

isotonic/hypotonic environment

26
Q

environment that causes plasmolysis, water loss, inhibits growth

A

hyperosmotic environment

27
Q

application: use of salt or sugar as preservative (4)

A

 salting of fish
 sugaring of fruits
 brining of vegetables
 jams, marmalades, preserves, and pickles

28
Q

organisms that can grow at relatively high salt concentration (up to 10%)

A

osmotolerant

29
Q

salt-loving organisms; require relatively high salt concentrations for growth (i.e. archea require NaCl concentrations of 20 % or higher)

have transport systems to regulate movement of substances

require moderate to large quantities of salt

typically found in the ocean (optimum: 3.5% salt concentration)

found in exceptionally salty bodies of water (Dead Sea, brine vats)

A

halophiles

30
Q

halophiles classification

A

 low halophiles – 1-6% NaCl
 mild or moderate halophiles – 6-15% NaCl
 extreme halophiles – 15-30% NaCl

31
Q

halophile that is thriving in the Dead Sea

A

Dunaliela salina

32
Q

pressure exerted by standing water, in proportion to its depth

  • doubles with every 10 meter increase in depth
A

hydrostatic pressure

33
Q

bacteria that live at high pressures

  • membranes and enzymes (3-D configuration) require high pressure to function properly
  • exhibit optimal reproduction rates at hydrostatic pressures exceeding 10MPa, found throughout the deep-biosphere
A

piezophiles (barophiles)

34
Q

In ____, all known bacterial piezophiles fall into this category. They exhibit optimal reproduction rates at hydrostatic pressures exceeding 10MPa and at temperatures ranging from 2-4°C, found throughout the deep-biosphere

A

Psychropiezophiles

35
Q

With ____, the only current example is the archaeon Pyrococcus yayanosii. They exhibit optimal reproduction rates at 52MPa and 98°C.

A

Thermopiezophiles

36
Q

With ____, visible light is the source of energy for photosynthesis (photosynthetic microorganisms: Cyanobacteria, Volvox).

A

Radiation/Radiant Energy

37
Q

What is the difference between Direct Damage and Indirect Damage by ionizing radiation?

A

Direct Damage - Direct sa DNA
Indirect Damage - muagi pag laing molecule (superoxide)

38
Q

How do most bacteria reproduce?

A

Binary Fission

39
Q

What happens in binary fission? (5)

A
  1. replication of chromosomes
  2. cells double in size
  3. septum formation
  4. completion of septum with formation of distinct walls
  5. cell separation
40
Q

interval for the formation of two cells from one cell

A

generation

41
Q

interval of time between for two cells to form from one cell

the time required for a bacterium to give rise to 2 daughter cells under optimum conditions

A

Generation Time

42
Q

Generation Time of the ff:
1. Escherichia coli - ___
2. Staphylococcus aureus - ___
3. Mycobacterium tuberculosis - ___
4. Treponema pallidum - ___

A

Escherichia coli - 20 mins
Staphylococcus aureus - 27-30 mins
Mycobacterium tuberculosis - 792-932 mins
Treponema pallidum - 1980 mins

43
Q

formulas for generation time and everything

k = number of generations that occur per unit time in
an exponentially growing culture
N = final cell number
No = initial cell number
n = no. of generations that have occurred during the period of exponential growth
g = generation time
t = hours or minutes of exponential growth

A

N = No2^n

g = t/n

n = (log N- log N0) / log 2

k = ln 2 / g

44
Q

What are the four phases of bacterial growth curve? (4)

A
  1. Lag Phase - maximum cell size towards the end of lag phase.
  2. Log Phase - smaller cells, stain uniformly.
  3. Stationary Phase - irregular staining, sporulation and production of exotoxins.
  4. Phase of Decline - involution forms (with aging).
45
Q

In the ____ phase,

  • NO significant or immediate increase in cell numbers
  • there may be an increase in the size of the cell
  • ADAPTATION phase
  • is metabolically ACTIVE
  • the period when microorganisms are introduced into fresh culture medium
A

Lag

46
Q

In the ____ or ____ phase, cells start dividing and their number increases exponentially.

  • organisms divide at their most rapid rate
  • population of organisms DOUBLES in each generation time
  • HEALTHIEST state
  • Here, bacteria are MORE SUSCEPTIBLE to antibiotics.
A

Log (Logarithmic); Exponential

47
Q

In the ____ phase,

  • cell division decreases due of nutrients and accumulation of toxic products; inadequate oxygen supply; pH change.
  • Here, growth rate TAPERS OFF.
  • Equilibrium EXISTS between dying cells and the newly formed cells (new cells produced at the same rate as old cells die).
  • Cell functions continue.
  • production of secondary metabolites (small, bioactive molecules) occur.
A

Stationary

48
Q

n the ____ phase, the population decreases due to the DEATH of cells.
Here, conditions in the medium become less and LESS SUPPORTIVE of cell division.
The number of live cells DECREASES at a logarithmic rate (but slower).
Cells undergo LYSIS or INVOLUTION (assume a variety of unusual shapes).
There are also more spores than vegetative cells that survive.

A

Decline (Death)

MCB LEC (9 decks)

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