Ch.6 : Microbial Growth Flashcards

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1
Q

Physical Requirements for Growth

A

Temperature
pH
Osmotic Pressure

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2
Q

Chemical Requirements for Growth

A
CARBON
NITROGEN
PHOSPHOROUS
Sulfur
Trace Elements
Oxygen
Organic Growth Factor
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3
Q

Microbes classified into 3 groups based on temperature

A

Psychrophiles
Mesophiles
Thermophiles

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4
Q

Psychrophile

A

Cold-loving microbes. 0-20 Degrees Celsius

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5
Q

Mesophile

A

Moderate-temperature loving microbes 20-45 Degrees Celsius

Most disease-causing bacteria prefer 35-40 Degrees Celsius

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6
Q

Thermophiles

A

heat-loving microbes. 55-85 Degrees Celsius

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7
Q

*Psychrotrophs

A

0-35 Degrees Celsius

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8
Q

*Hyperthermophiles

A

85-113 Degrees Celsius

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9
Q

Minimum Growth Temperature

A

Lowest temperature at which the species will grow

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10
Q

Optimum Growth Temperature

A

Temperature which species grow best.

Microbes cannot regulate internal temperature

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11
Q

Maximum Growth Temperature

A

Highest temperature at which growth is possible.

High temperatures may inhibit enzyme functioning and be lethal.

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12
Q

Acidophiles

A

growth optimum between pH 0 and pH 5.5

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13
Q

Neutrophiles

A

growth optimum between pH 5.5 and pH 7

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14
Q

Alkaliphiles (alkalophiles)

A

growth optimum between pH 8.5 and pH 11.5

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15
Q

Plasmolysis

A

Shrinkage of cell’s cytoplasm

Microorganisms composition is 80-90% water

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16
Q

Hypotonic

A

Increase osmotic pressure (cell fills up)

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17
Q

Hypertonic

A

Decrease osmotic pressure (cell shrivels)

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18
Q

Trace Elements

A

Iron, Copper, Molybdenum, Zinc

Essential for the functions of certain enzymes, usually as cofactors. Too much is toxic

19
Q

Halotolerant microbe found on human skin

A

Staphylococcus aureus

Halo = Salt

20
Q

Obligate Aerobes

A

absolute requirement for oxygen

ex. Pseudomonas

21
Q

Obligate Anaerobes

A

cannot tolerate any oxygen (toxic)

ex. Clostridium

22
Q

Facultative Anaerobes

A

grow better with oxygen, but can grow just fine without it also; facultative means flexible

ex. E. coli

23
Q

microaerophiles

A

require small amounts of oxygen (2-10%) but large amounts are toxic

ex. Helicobactern pylori

24
Q

aerotolerant anaerobes

A

indifferent to oxygen; can grow in the presence of oxygen, but never use it to produce energy; obligate fermenters

ex. Streptococcus pyogenes (strep throat), lactic acid bacteria

25
Q

Singlet Oxygen

A

O2- that has been boosted into a higher energy state and is extremely toxic

26
Q

Superoxide free radicals

A

A toxic anion (O2-) with an unpaired electron

Must produce superoxide dismutase (SOD) to neutralize

27
Q

Peroxide Anion

A

An oxygen anion consisting of two atoms of oxygen (O2^-2)

Must produce catalase to neutralize it

28
Q

Hydroxyl Radical

A

A toxic form of oxygen (OH) formed in cytoplasm by ionizing radiation and aerobic respiration

29
Q

Fastidious Organisms

A

organisms that cannot synthesize everything they need and require supplemental growth factors

ex. Neisseria (need all 20 aa, 7 vitamins), Mycoplasma

30
Q

Non-Fastidious Organisms

A

versatile, do not require supplemental growth factors

ex. E. coli, P. aeruginosa

31
Q

Biofilms

A

A microbial community that usually forms as a slimy layer on a surface

Can be formed on any conditioned surface; Hard to remove
Very complex communities

32
Q

Quorum sensing

A

Cell-to-cell chemical communication allows bacteria to coordinate their activity and group together into communities.

33
Q

Planktonic

A

Free swimming bacterium

34
Q

Sessile

A

Grow attached to surfaces

35
Q

Extracellular Polymeric substance (EPS)

A

a glycocalyx that permits bacteria to attach to various surfaces

36
Q

Binary Fission

A

Prokaryotic cell reproduction by division into two daughter cells

37
Q

Lag Phase

A

The time interval in a bacterial growth curve during which there in no growth

38
Q

Log phase

A

The period of bacterial growth or logarithmic increase in cell numbers; also called exponential growth phase

39
Q

Stationary Phase

A

The period in a bacterial growth curve when the number of cells dividing equals the number of dying

40
Q

Death Phase

A

The period of logarithmic decrease in a bacterial population; also called logarithmic decline phase

41
Q

Direct Measurement (counting chamber)

A

counts both live and dead cells

42
Q

Indirect Measurement (Spectrophotometry)

A

measures absorption or transmittance of light at 600nm wavelength

both live and dead cells absorb light

43
Q

Turbidity

A

the cloudiness of a suspension

44
Q

Direct Measurement (Viable Cell Count)

*also called Dilution plating

A

counts only live cells
each viable cell leads to a colony
count colony forming units (cfu)