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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
Carrier-mediated (active)
molecules pumped in & out of cell via protein pumps
26
Group translocation (active)
molecules are moved across membrane and converted into useful substances at the same time
27
Bulk active transport
transport of large molecules - endocytosis - exocytosis
28
Phagocytosis
internalizing solid particles | membrane wrapped
29
Pinocytosis
small particles and water are brought into the cell ("to drink")
30
Phototroph
energy source: sun
31
Chemotroph
energy source: chemical (ingest and breakdown)
32
Heterotroph
carbon source = organic carbon | pathogens are heterotrophs
33
Autotroph
carbon source = inorganic CO2 - can convert CO2 into organic compounds - not nutritionally dependent on other living things
34
Photoautotrophs
energy: photosynthetic carbon source: inorganic CO2 to produce organic molecules ex. cyanobacteria, algae, plants
35
Chemoautotrophs
energy: chemical carbon source: CO2 ex. archaea
36
Photoheterotrophs
energy: photosynthetic carbon source: organic (uses carbs, fatty acids, and alcohols) ex. purple and green photosynthetic bacteria
37
Chemoheterotrophs
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
Obligate aerobes
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
Obligate anaerobe
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
Facultative anaerobe
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
Aerotolerant aerobes
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
Microaerophiles
require small amts of oxygen | ex. H. pylori
43
Acidophiles
thrive in acidic environments | ex. H. pylori
44
Alkalinophiles
thrive in alkaline environments | ex. Proteus can create alkaline conditions to neutralize urine and colonize and infect the urinary system
45
Halophiles
salt lovers requires high salt concentrations withstands hypertonic conditions ex. Halobacterium
46
Facultative halophiles
can survive high salt conditions but is not required | ex. S. aureus
47
Radiation
UV, infrared | can cause death or evolution in the bacteria
48
Barophiles
withstand high pressures
49
Spores and cysts
can survive dry habitats
50
Antagonism (nonsymbiotic)
free living species compete | some members are inhibited or destroyed by others
51
Antibiosis
the production of inhibitory compounds such as antibiotics
52
Synergism (nonsymbiotic)
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
Quorum sensing
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
Benefits of biofilm
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
Direct count for measuring microbial growth
actually counting the microbes
56
Indirect count for measuring microbial growth
counting something that indicates the amt of microbes
57
Symbiotic
organisms live in close nutritional relationships | required by one or both members
58
Nonsymbiotic
organisms are free living | relationships not required for survival

BI 234 (16 decks)

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