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BI 234 > Exam 2: Ch 6: Microbial Nutrition & Growth > Flashcards

Exam 2: Ch 6: Microbial Nutrition & Growth Flashcards

1
Q

Growth

A

number of cells (not size)
population growth
dictated by length of generation time
exponential, not arithmetic

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2
Q

Binary fission

A

the division of a bacterial cell
parental cell enlarges and duplicates its DNA
Cell wall and plasma membrane begin to divide
Cross wall forms completely around DNA - septum formation divides the cell into 2 separate chambers
cells separate - complete division results in 2 identical cells (daughter cells)
dont necessarily replicate plasmids/may not have the ones they started with

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3
Q

Generation time

A

time required for a complete division cycle (doubling)
length of generation time = measure of the growth rate
dependent on chemical/physical conditions (the environment)
avg generation time for a pathogen: 30-60 minutes

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4
Q
  1. Lag phase
A

cells are adjusting, enlarging, and synthesizing critical proteins and metabolites to grow
right after inoculation
changing gene expression to make them more fit for new environment

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5
Q
  1. Exponential growth phase (Log)
A

max exponential growth rate of cell division - fastest rate
adequate nutrients
favorable environment (havent produced enough waste)
most sensitive to antibiotics: they’re growing & antibiotics attack ribosomes and those are needed to make proteins and grow
-making peptidoglycan so they arent totally protected yet
-person actively shedding in the early/middle stages of infection = more likely to spread b/c there is more bacteria in the shedded products b/c they are growing faster

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6
Q
  1. Stationary phase
A

cell birth rare = cell death rate

survival mode - depletion in nutrients, waste is starting to build up

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7
Q
  1. Death phase
A

cells begin to die exponentially due to the lack of nutrients and build up of waste
more and more dead cells at the bottom
some cells will remain viable

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8
Q

Standard plate count (direct measurement)

A

most common
DILUTE to get individual countable colonies
can distinguish btwn living and dead (the living ones are the ones growing)
(1:10 dilution - 1 ml of culture, 9ml of broth)
1ml of original culture taken out, put in new tube, plate (gets more dilute as you continue the process)

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9
Q

Microscopic count (direct measurement)

A

count w/microscope
Easy and fast
Uses special microscope counting slide
does not differentiate btwn live and dead bacteria

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10
Q

Membrane Filtration (direct measurement)

A

when # of microbes is small - very dilute
have a filter, run that liquid through, plate that, let it grow
can distinguish btwn living and dead cells (if you are growing microbes, you will only see living)

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11
Q

Coulter counter (direct measurement)

A

automated cell counter
electronic sensor detects and counts the # of cells
counts living and dead

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12
Q

Turbidity (indirect/estimation)

A

more bacteria –> more cloudiness
can measure w/spectrometer or eye
Turbidity using spectrometer:
Spectrometer shines light, then it detects the light (light absorbed = microbes)

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13
Q

Metabolic activity (indirect/estimation)

A

assumes amt of metabolic product is proportional to #
the metabolic output or input of a culture can be used to estimate viable count
ex. measure how fast gases and/or aids are formed in a culture
ex. the rate a substrate like glucose or oxygen is used up
can distinguish btwn living and dead cells

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14
Q

Dry weight (indirect/estimation)

A 
used for filamentous organisms (like molds)
to calculate the dry weight of cells
-cells separated from the medium
-dried
-resulting mass is weighed
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15
Q

Genetic probing (indirect/estimation)

A

real time PCR to “count” how many bacterial genes there are in a sample
The most accurate
Can identify a single cell in a sample
Using genetic analysis to count
Does not distinguish btwn living and dead (living and dead both have DNA)

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16
Q

Growth measurements that can distinguish btwn living and dead cells:

A

standard plate counts
filtration
metabolic activity

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17
Q

Macronutrients

A

carbon, hydrogen, oxygen

required in relatively large quantities and play principal roles in cell structure and metabolism

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18
Q

Micronutrients (trace)

A

present in much smaller amts

manganese, zinc, nickel

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19
Q

Inorganic nutrients

A

have carbon OR hydrogen (not both)

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20
Q

Organic nutrients

A

has carbon-hydrogen bond

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21
Q

Passive transport

A

molecules transported along concentration gradient
doesnt require energy
-simple diffusion
-facilitated diffusion

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22
Q

Active transport

A

molecules transported against concentration gradient
requires energy
-carrier mediated
-group translocation

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23
Q

Simple diffusion (passive)

A

transport of small, neutral, hydrophobic molecules through membrane (H2O, CO2, O2)

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24
Q

Facilitated diffusion (passive)

A

transport of large, charged, hydrophilic molecules
-channel proteins
-carrier proteins
proteins –> hallway

25
Q

Carrier-mediated (active)

A

molecules pumped in & out of cell via protein pumps

26
Q

Group translocation (active)

A

molecules are moved across membrane and converted into useful substances at the same time

27
Q

Bulk active transport

A

transport of large molecules

  • endocytosis
  • exocytosis
28
Q

Phagocytosis

A

internalizing solid particles

membrane wrapped

29
Q

Pinocytosis

A

small particles and water are brought into the cell (“to drink”)

30
Q

Phototroph

A

energy source: sun

31
Q

Chemotroph

A

energy source: chemical (ingest and breakdown)

32
Q

Heterotroph

A

carbon source = organic carbon

pathogens are heterotrophs

33
Q

Autotroph

A

carbon source = inorganic CO2

  • can convert CO2 into organic compounds
  • not nutritionally dependent on other living things
34
Q

Photoautotrophs

A

energy: photosynthetic
carbon source: inorganic CO2 to produce organic molecules
ex. cyanobacteria, algae, plants

35
Q

Chemoautotrophs

A

energy: chemical
carbon source: CO2
ex. archaea

36
Q

Photoheterotrophs

A

energy: photosynthetic
carbon source: organic (uses carbs, fatty acids, and alcohols)
ex. purple and green photosynthetic bacteria

37
Q

Chemoheterotrophs

A

energy and carbon source: organic compounds (chemicals and organic carbon)
vast majority of microbes causing human disease are these
ex. most bacteria (that we know of), all pathogens, all fungi, all animals, all protozoans

38
Q

Obligate aerobes

A

require oxygen for metabolism
have enzymes that neutralize toxic organic metabolites (catalase)
ex. most fungi, protozoa, and bacteria (bacillus species and Myobacterium TB)

live on top of the tube (higher O2 on top, none at the bottom)

39
Q

Obligate anaerobe

A

cannot use oxygen for metabolism
dont possess superoxide dismutase or catalase
the presence of oxygen is toxic to the cell and will kill it
ex. many oral bacteria, intestinal bacteria
cannot be around O2, live at bottom, cant use oxygen gas (o2) as a way to make ATP

40
Q

Facultative anaerobe

A

doesnt need it but can grow w/O2
during oxygen free states, anaerobic respiration or fermentation occurs
possess superoxide dismutase and catalase
ex. many gram - pathogens

prefer oxygenated environments b/c more energy is produced during aerobic respiration
have to have some type of protection against O2;

41
Q

Aerotolerant aerobes

A

can live with, but do not use oxygen for metabolism
able to break down peroxides (not using catalase)
ex. some lactobacilli and streptococci
grow all over the tube b/c they can grow w/O2 but don’t need it so they’re totally oblivious to the O2 gradient

42
Q

Microaerophiles

A

require small amts of oxygen

ex. H. pylori

43
Q

Acidophiles

A

thrive in acidic environments

ex. H. pylori

44
Q

Alkalinophiles

A

thrive in alkaline environments

ex. Proteus can create alkaline conditions to neutralize urine and colonize and infect the urinary system

45
Q

Halophiles

A

salt lovers
requires high salt concentrations
withstands hypertonic conditions
ex. Halobacterium

46
Q

Facultative halophiles

A

can survive high salt conditions but is not required

ex. S. aureus

47
Q

Radiation

A

UV, infrared

can cause death or evolution in the bacteria

48
Q

Barophiles

A

withstand high pressures

49
Q

Spores and cysts

A

can survive dry habitats

50
Q

Antagonism (nonsymbiotic)

A

free living species compete

some members are inhibited or destroyed by others

51
Q

Antibiosis

A

the production of inhibitory compounds such as antibiotics

52
Q

Synergism (nonsymbiotic)

A

free-living species benefits together but is not necessary for survival
cooperate and share nutrients to produce a result that none of them could do alone

gum disease, dental caries, and some bloodstream infections involve mixed infections of bacteria interacting synergistically

53
Q

Quorum sensing

A

communicate w/chemicals

used by bacteria to interact with members of the same species as well as members of other species that are close by

54
Q

Benefits of biofilm

A

large, complex communities form w/different physical and biological characteristics
the bottom may have very different pH and oxygen conditions than the surface
partnership among multiple microbial species
cannot be eradicated by traditional methods

55
Q

Direct count for measuring microbial growth

A

actually counting the microbes

56
Q

Indirect count for measuring microbial growth

A

counting something that indicates the amt of microbes

57
Q

Symbiotic

A

organisms live in close nutritional relationships

required by one or both members

58
Q

Nonsymbiotic

A

organisms are free living

relationships not required for survival

BI 234 (16 decks)

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