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MCB 2610 > EXAM 2-Chapter 7 part 2 > Flashcards

EXAM 2-Chapter 7 part 2 Flashcards

1
Q

Complex media

A

Know that it has all necessary macro and micronutrients but do not know specific concetrations

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2
Q

synthetic (defined) media

A

know everything in it and their concentrations

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3
Q

If you aren’t sure the nutrient requirements of your organism which media do you use?

A

synthetic

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4
Q

Components of complex media

A

peptones
extracts
agar

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5
Q

Peptones

A

Protein hydrolysates prepared by partial digestion of various protein sources

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6
Q

Peptones importance

A

break down into amino acids and supply macro and micronutrients

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7
Q

Peptone examples

A

gelatin
caseins
meats

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8
Q

Extracts

A

aqueous extracts usually of beefs or yeasts

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9
Q

Extract importance

A

supply macro and micronutrients

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10
Q

Agar

A

sulfated polysaccharide used to solidify media
usually extracted from red algae

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11
Q

Agar importance

A

melts at high temp- solidifies when cooled
most organisms cannot digest/degrade agar

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12
Q

functional media types

A

supportive/general purpose media
enriched media (supportive+)
Differential media
Selective media

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13
Q

Supportive/general purpose media

A

main function is to just grow your ordinary microorganisms
can grow a wide vareity of them

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14
Q

enriched media

A

general media plus some nutrients

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15
Q

What is enriched media used to grow?

A

Fastidious microorganisms

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16
Q

Fastidious microorganisms

A

Very picky and grow really slow on regular media

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17
Q

Differential

A

distinguishes between different groups based on their biological characteristics

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18
Q

Selective

A

favors the growth of some microorganisms and inhibits the growth of others

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19
Q

What type of media is blood agar?

A

enriched
functional- differential

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20
Q

Blood agar

A

Contains sheep red blood cells
differential: if lysis occurs a clear zone forms around the growth

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21
Q

What type of media is MacConkey agar>

A

complex
functional- differential and selective

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22
Q

MacConkey agar

A

differential- contains lactose and if fermentation occurs agar turns pink
selective- contains biosalts that allow growth of Gram-neg and inhibit Gram-positive bacteria

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23
Q

Why can Gram-negative bacteria grown on MacConkey agar?

A

Have an outer membrane that keeps bio salts out

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24
Q

pure culture

A

a plate with a single isolated culture

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25
3 techniques for isolating colonies
Streak plate- T-streak Spread plate Pour plate
26
T streak method
spreading mixture of cells ON agar surface so that individual cells are separated from one another involves bacteriological loop
27
Spread plate method
Make bacterial dilutions pour 0.1mL on agar plate and spread with "hockey stick" Bacteria grows ON surface
28
Pour plate method
make bacterial dilutions put dilutions into molten agar and vortex to mix cells Pour molten agar and bacteria mix into empty Petri dish Bacteria grown ON and IN agar
29
Why cant we grow all microrganisms in lab?
we cannot replicate appropriate growth conditions symbiotic relationships that we cannot recreate
30
How do we gain information about unculturable bacteria?
PCR Fluorescent in situ Hybridization (FISH) Metagenomics
31
PCR
DNA from unulturable bacteria can be amplified
32
FISH
sequences can be used to produce fluorescent probes that will bind to complementary DNA
33
Metagenomics
Take all DNA in a sample and get all genes in sequence
34
Limitations/drawbacks of metagenomics
results in a lot of info that must be analyzed Results must still be confirmed in culture media
35
Microbial Consortia
Unculturable bacteria organisms that will not grow on their own; require symbiotic relationship
36
Where are microbial consortials commonly found and give example?
interfaces between water and land EX: biofilms
37
Bacterial colony morphology
Can tell us some things but not everything cannot use morphology alone to determine microorganims
38
Differential colony morphology
the same colonies look different when grown in different conditions/on different media
39
Direct counts
see cells and count them
40
Two methods of direct counts
Direct count with Petroff-Hausen chamber Flow cytrometry
41
Direct Count with Petroff Hausen chamber
uses a smaller aliquot to measure larger culture
42
petroff Hausen champer procedure
load knwon volume onto gridded side count under a light microscope
43
petroff-haussen chamber limitations
Can lose accuracy need to ensure aliquot is representative of entire culture- mixed well
44
Flow cytometry
microbial suspension is forced through a small orface with a laser beam gives more accuracy
45
Flow cytometry procedure
one cell moves through light beam at a time and distrupts electrical current When disruption happens the machine counts
46
Specific antibodies and flow cytometry
specific antibodies can be used to determine size and internal capacity EX: set to recognize fluorescence with a live-dead stain or fluorescent probe
47
Limitations of Flow cytometry
very large and expensive requires training
48
Visible counts
serial dilutions and measure as colony forming unites (CFU)
49
Visible counts process
create spread plate and pour plate take dilutions at different times and spream 0.1mL on plate COunt number of colonies on plate (avg) and divide by dilution (CFU/mL)
50
What is a reliable number of colonies for CFU?
20-400
51
What happens if starting culture is already diluted for CFU?
will not give a reliable count must concentrate first
52
How to concentrate already diluted cultures?
filtering apparatus cells get stuck on filter, transfer membrane filture onto growth medium and incubate
53
Turbidity
as culture gets more dense it gets cloudier and the absorbance increases
54
How to take turbidity measurements?
spectrophotometer sends light through culture If tube is cloudy, light will not pass through and strike sensor
55
What does spectrophotometer find?
OD600 optican density at wavelength of 600
56
What is a CFU?
Colony forming unite used to estimate the number of viable microbial cells in a sample
57
How to calculate CFU?
Count the number of colonies on the plate (average) and divide by the dilution Gives CFU/mL
58
Indirect measurements of cell mass
Dry weight Quantity of a particular cell constituent
59
Dry weight
putting cells on a balance and weighing it
60
How to get cells for dry weight
Take 5L of culture Spin in multiple centrifuge tubes to separate pellet Pour liquid and resuspend Continue process multiple times
61
Limitations fo dry weight
time consuming not very sensitive can lose cells when pouring out liquid
62
Quantity of a particular cell constituent
using an assay of constituent As constituent increases so are the sells
63
When can you use as a cell constituent?
protein DNA ATP Chlorophyll
64
What are limitations of using cell constituents?
Must pick the right constituent - cannot fluxuate randomly in cell - needs to be expressed all the time

MCB 2610 (24 decks)

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