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Microbiology > Chapter 6 Microbial Growth > Flashcards

Chapter 6 Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

Microbial “Growth”

A
  • increase in population of microbes
  • result of growth is a discrete colony
  • reproduction>growth
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2
Q

Colony

A

aggregation of cells arising from a single parent

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3
Q

Growth Requirements

A
  • nutrients for energy + for building organic molecules
  • common nutrients: c, o, n, h
  • microbes obtain nutrients fr various sources
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4
Q

organisms that require CARBON SOURCE for energy

A

Autotrophs + Heterotrophs

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5
Q

organisms that require energy source

A

Chemotrophs + Phototrophs

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6
Q

Autotrophs

A

require CO2

-food producers, dont need to eat

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7
Q

Heterotrophs

A

require organic compound (carbon-containing compounds)

-must obtain food fr other sources

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8
Q

organisms that require light + CO2

A

Photoautotrophs (plants, algae, cyanobacteria)

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9
Q

organisms that require chem compounds + CO2

A

Chemoautotrophs (uses specific chem compounds like hydrogen, sulfur, + nitrifying bacteria + some archaea)

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10
Q

organisms that require light and organic compound

A

Photoheterotroph (food consumers but can also use light)

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11
Q

organism that require chem compound + organic compound

A

Chemoheterotroph (animals, fungi, protazoa, bacteria, yeast, archaea)

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12
Q

4 types of oxygen requirements for bacteria

A

1 Obligate Aerobes
2 Obligate Anaerobes
3 Facultative Anaerobes
4 Aerotolerant Anaerobes

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13
Q

Obligate Aerobes

A
  • O is essential for life

- aerobic resp ONLY

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14
Q

Obligate Anaerobes

A
  • O is deadly
  • toxic forms of O are highly reactive + excellent oxidizing agents
  • O causes irreparable damage to cells bc missing key enzymes

-fermentation ONLY!

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15
Q

Facultative Anaerobes

A
  • can survive in O
  • will use cellular respiration if O is present,
  • can switch to fermentation if O is NOT present

-both fermentation + aerobic resp

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16
Q

Aerotolerant Anaerobes

A
  • tolerate presence of O bc they have enzymes

- fermenters

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17
Q

aerobes and facultative anaerobes have these enzymes that help tolerate toxic oxygen species

A

superoxide dismutase + catalase

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18
Q

Superoxide Dismutase

A

neutralizes oxygen radicals which are toxic

ex)
O2- > O2
O2 + 2H+ > H2O2

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19
Q

Catalase

A

neutralize peroxide

ex)
H2O2 > 2H2O + O2
peroxide > water and oxygen

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20
Q

4 forms of Toxic Oxygen

A

1 singlet oxygen
2 superoxide radicals
3 peroxide anion
4 hydroxyl radical

-unstable forms of oxygen that has extra electrons that they are trying to get rid of

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21
Q

Catalase Test

A
  • determines if bacteria has enzyme catalase
  • hydrogen peroxide is added to bacteria. if bubble/foams, then positive for catalase
    ex) staph cocci vs strep cocci: staph is catalase pos.
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22
Q

4 Microbe Types based on Temp Requirements

A

[ -5 to 20C] PSYCHROphiles
[ 15 to 45C] MESOphiles
[ 43 to 80C] THERMOPHILES
[67 to 105C] HYPERTHERMOphiles

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23
Q

most pathogenic bacteria based on temp

A

Mesophiles [15 to 45C]

24
Q

pH requirements for microbes

A
  • organisms are sensitive to changes in acidity

- H+ and OH- interfere with H bonding

25
Q

3 Microbe Types based on pH Requirements

A

Neutrophiles (most human pathogens)
Acidophiles
Alkalinophiles

26
Q

Water requirements for microbes

A
  • water is required to dissolve enzymes + nutrients
  • water is important reactant in many metabolic rxn
  • when water is not present, bacteria may undergo sporation
27
Q

2 physical effects of water on microbes

A

1 osmotic pressure

2 hydrostatic pressure

28
Q

Osmotic Pressure

A
  • pressure exerted on a semipermeable membrane by a soln containing solutes that cannot freely cross
  • water can freely cross
  • water will follow salt/ions
29
Q

Hypotonic Soln

A

lower solute concentration

30
Q

Hypertonic Soln

A

higher solute concentration

31
Q

Obligate + Facultative Halophiles

A

organisms that live in high salt concentration

32
Q

Biofilms

A
  • complex relationships among numerous organisms
  • from slime layer + fimbraea
  • form on surfaces as a result of quorum sensing
  • many organisms in a biolfilm are more harmful than a colony of a single type
33
Q

Biofilm Extracellular Matrix

A
  • adhere cells to one another
  • allows attachment to a substrate
  • sequester nutrients
  • may protect individuals in the biofilm
34
Q

Inoculum/Inoculation

A

introduction of microbes from one place to another medium

-for collecting environmental, clinical, and stored specimens

35
Q

Culture

A

act of cultivation microbes

36
Q

Obtaining Pure cultures

A
  • cultures composed of cells arise from a single progenitor [CFU-colony forming unit]
  • aseptic technique
  • isolation technique
37
Q

2 Isolation Techniques

A

streak plates

pour plates

38
Q

Pour Plate Method

A 
-dilution of sample by factors of 10
1mL of initial sample into 9mL of broth
1mL of diluted sample into 9mL of broth
repeat and then 
1mL of diluted sample into 9mL warm agar
39
Q

6 types of Culture Media

A 
1 Selective Media
2 Differential Media
3 Defined Media
4 Complex Media
5 Anaerobic Media
6 Transport Media
40
Q

Differential Medium: Blood Agar

A

-checks for pathogenic form of strepto cocci (Beta-Hemolysis, Alpha-Hemolysis, Gamma-Hemolysis)

  • beta (positive hemolysis of rbc)
  • alpha (some clearing, greenish, partial hemolysis, causes pneumonia)
  • gamma (no hemolysis, no clearings, found in oral cavity)
41
Q

Hemolysis

A

destruction of red blood cells

42
Q

MacConkey

A
  • selective+differential media
  • selects for Gram-Neg bacteria
  • differentiates bw Gram-Neg for Lactose Fermentation
43
Q

MacConkey

A
  • selective+differential media
  • selects for Gram-Neg bacteria (gram-pos will not grow)
  • differentiates bw Gram-Neg for Lactose Fermentation (medium turns yellow if positive for fermentation)
44
Q

Preservation of Cultures

A
  • refrigeration (stores for short period of time)
  • deep-freezing (stores for years)
  • lyophilization or freeze-drying (decades)
45
Q

Bacterial Growth

A
  • binary fission

- increasing number of bacterial cells

46
Q

Generation Time

A

time required for bacterial cell to grow and divide

  • amt of time for 1 cell to grow into 2 cells
  • dependent on chem + physical conditions
  • varies among different bacterial species
47
Q

Arithmetical Growth

A

constant increase. straight line

48
Q

Logarithmic Growth

A

. grow at an exponential level each time their generation time is up. curved, to steep line

49
Q

Microbial Growth Curve

A

Lag Phase
Log (exponential) Phase
Stationary Phase
Death (decline) Phase

50
Q

Chemostat

A
  • type of bioreactor
  • fresh medium is continuously added while culture liquid is continuously removed to keep culture volume constant
  • can control the growth rate of microbes by changing the rate w which the medium is added
51
Q

Serial Dilution + Viable Plate Count

A

ways to measure microbial reproduction

52
Q

Metabolic Activity

A
  • distinguishes live and dead cells

- indirect methods of measuring microbial reproduction

53
Q

Lag Phase

A

bacteria is floral sensing

-in new environment, learning what nutrients + amino acids are available.

54
Q

Log Phase

A

-number of bacteria grows exponentially until there is no more room to grow.

55
Q

Stationary Phase

A

maxed out, no more room for growth

Microbiology (26 decks)

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