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BIO 442 > Microbial Nutrition and Growth > Flashcards

Microbial Nutrition and Growth Flashcards

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Biology 101 flashcards
1
Q

What is carbon used for in organisms?

A

everything?

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2
Q

What is quorum sensing?

A

bacteria communicate with each other by secreting molecules. signals can lead to new genes being expressed.

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3
Q

Carbon source for photoautotrophs

A

CO2

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4
Q

What are superoxide free radicals?

A

an oxygen-based free radical

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5
Q

Which type of organisms are most likely to contaminate a brine (salt) solution found in pickles?

A

halophiles

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6
Q

Describe plate counts

A

count colonies on plate, colonies between 25-250

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7
Q

describe most probable number

A

best guess at cell number based on the fact that more dilutions are required for a denser culture. used for organisms that don’t grow well in solid media. Use different dilutions and dye indicators

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8
Q

lag phase

A

cells not actively dividing, adjusting to environment

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9
Q

What ingredient is added to make liquid media solid or semi-solid?

A

agar

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10
Q

Describe two methods for obtaining isolated colonies.

A

streak plates and pour plate

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11
Q

Describe binary fission. Describe how to calculate the number of cells after each round.

A

binary fission is the splitting of a bacterial cell. They split into two every time.

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12
Q

Define facultative anaerobes, where they are in the tube, and a species example

A

prefer O2 but can adapt to a lack of it
E.coli

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13
Q

define microaerophiles, where they are in the tube, and an example

A

prefer a low oxygen environment
campylobacter jejuni

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14
Q

What macromolecules require nitrogen?

A

amino acids, DNA, RNA, and proteins

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15
Q

Energy source for chemotrophs

A

organic and inorganic chemicals

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16
Q

What is a colony?

A

cluster of cells that can be seen with the naked eye and originated from 1 cell

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17
Q

Carbon source for chemoheterotrophs

A

organic chemicals

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18
Q

describe direct microscopic count

A

individual cells are counted using a special cell counter and adding a known volume of the inoculum

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19
Q

describe metabolic activity indirect measurement

A

production of a product or utilization of a substrate used to estimate cell number

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20
Q

define obligate anaerobes, where they are in the tube, and example

A

cannot live in the presence of O2
clostridium

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21
Q

Define obligate aerobes

A

need O2 to live

22
Q

stationary phase

A

no net growth, # of cells dividing and dying are at equal rates

23
Q

Which type of organisms are most likely to contaminate and grow in the refrigerator?

A

psychrotolerant

24
Q

define capnophiles

A

thrive in a high level of CO2

25
Q

What reaction does catalase catalyze?

A

coverts hydrogen peroxide into H2O and O2

26
Q

Carbon source for chemoautotrophs

A

inorganic molecules, fix their own C

27
Q

During which phase are bacteria most susceptible to antibacterial agents?

A

log phase

28
Q

What temperature do pathogenic organisms grow best at?

A

37 C

29
Q

describe dry weight measurment

A

used fo molds. cells are collected, dried, and then weighed

30
Q

Define generation time.

A

time to split into 2 cells

31
Q

Describe the range of temperature of growth for the following organism types:
a. thermophiles (including extreme)
b. mesophiles
c. psychrotolerants (psychrotrophs)
d. psychrophiles

A

a. thermophiles (including extreme)- 45-105 C
b. mesophiles- 15-45 C
c. psychrotolerants (psychrotrophs)- 0-40 C
d. psychrophiles- -5-20 C

32
Q

What three enzymes are important for neutralizing superoxide free radicals? How do they function?

A

SOD- conversion of superoxide free radical and free H+ ions into hydrogen peroxide and oxygen
catalase- converts hydrogen peroxide to H2O+O2
peroxidase- converts hydrogen peroxide and H+ ions into H2O

33
Q

describe turbidity (spectrophotometry/nephelometry)

A

cloudiness of the suspension is used to approximate the number of cells. Light is shone through the mixture and the percentage of light leaving the mixture determines the turbidity.

34
Q

Describe two ways to cultivate anaerobes.

A

reducing media or anerobe jar

35
Q

describe membrane filtration

A

cells in solution are poured through a membrane that catches the cells. Cells are transferred to media to be counted

36
Q

What macromolecules require sulfur and phosphorus?

A

amino acids and DNA/RNA

37
Q

define aerotolerant anaerobes, where they are in the tube, and an example

A

not killed by O2 but do not use it
streptococci

38
Q

death/decline phase

A

cells die off due to waste or lack of space or nutrients

39
Q

Carbon source for photoheterotrophs

A

organic chemicals

40
Q

Which microbes have SOD, catalase, or peroxidase?

A

obligate anaerobes have SOD and catalase
facultative anaerobes have SOD and catalase
aertolerant anaerobes have SOD but no catalase

41
Q

log phase

A

exponential growth, most sensitive to antimicrobial agents

42
Q

Describe two ways to store bacterial cultures.

A

fridge, deep freeze, freeze-drying

43
Q

How are biofilms different than their single species counter parts?

A

act differently

44
Q

Which pH do pathogenic organisms grow best at?

A

6.5-7.5

45
Q

What are some sources of nitrogen that bacteria use?

A

free amino acids, peptides, and proteins. Some use N2 gas

46
Q

Energy source for phototrophs

A

light

47
Q

How do high concentrations of salt and sugar affect cells?

A

plasmolysis, cell membrane pulls away from cell wall

48
Q

How do differential and selective media differ? Can a medium be both selective and differential?

A

differential media- differentiates the growths by growing style (color changing)
selective media- only allows for certain microbes to grow
yes

49
Q

Describe flow cytometry

A

single file flow of cells flow through a machine and light scatter is used to count them

50
Q

Define inoculum and culture (note there are different ways to use the word culture: noun, verb, adjective).

A

inoculum- cultural medium that contains microbes
culture (noun)- the thing you are growing
culture (verb)- to culture a bacteria

51
Q

How does defined media differ from complex media?

A

defined media everything is known quantities in the media
complex is a mixture of things and the exact quantities are not known

BIO 442 (26 decks)

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