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Completed > Labs 12-17 > Flashcards

Labs 12-17 Flashcards

0
Q

What color is Serratia marcescens

A

Red

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1
Q

What is a pure colony

A

Colony is assumed to be the identical progeny of the original cell and can be picked and used for further study

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2
Q

What color is Micrococcus luteus

A

Yellow/cream

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3
Q

Properties of agar

A

Polysaccharide produced by seaweed, adds no nutrient value

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4
Q

Melting point, solidifying point, pour temp of agar

A

Melting: 100C; solidifies: 42C;

Pour at 45-50C

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5
Q

What is the goal of a streak plate

A

To obtain a pure culture

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6
Q

What assumptions are made about each colony

A

Colony is assumed to be the identical progeny of the original cell and can be picked and used for further study

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7
Q

Why should agar plate be incubated upside down

A

To prevent condensation

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8
Q

Subculturing technique

A

Transfer a pure colony from plate to TSA slant

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9
Q

What number of colonies are considered statistically valid

A

30-300 CFU’s

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10
Q

The SPC method determines what type of cells

A

Only viable (live)

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11
Q

Optical density (absorbance) determines what type of cells

A

Both living and dead

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12
Q

What method is most common for determining bacterial numbers

A

The standard plate or viable count

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13
Q

Explain the relationship between turbidity and % T

A

As turbidity increases %T decreases

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14
Q

Formula to calculate optical density (OD)

A

OD = 2 - log (% T)
Ex: % T = 41.4
OD = 2 - log (41.4)
OD = 0.383

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15
Q

Describe the relationship between %T and OD

A

As %T goes up OD goes down

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16
Q

Describe the procedure for using the spec 20

A

Adjust the left knob to zero, insert blank and adjust the right knob to 100. Insert sample, close cover and read the %T.

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17
Q

Factors to keep in mind when using a wet mount to view motility

A

Examine under an oil immersion objective; use darkfield optics to view; look for directional movement; always examine immediately because motility decreases with time

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18
Q

Several facts about using hanging drop slides to view motility

A

Focus near the edge of the drop because most bacteria are drawn to the edge by surface tension; examine it quickly b/c water condensation may develop and decrease clarity

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19
Q

What is Brownian motion

A

Movement due to molecular bombardment of cells causing cells to shake or jiggle about but not move in any vectorial way

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20
Q

What was the genus and species of motile organisms used in lab

A

Proteus mirabilis

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21
Q

Pros and cons of using a wet mount to determine motility

A

Pro: doesn’t require incubation
Con: dehydrates quickly, spill possibility, Brownian motion

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22
Q

Pros and cons of using soft agar stab to determine motility

A

Pro: safest
Con: requires 18 hour incubation

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23
Q

What is the full name of the medium we used to determine oxygen requirements

A

FTM; fluid thioglycollate medium

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24
Q

What is the ingredient in FTM that acts to lower the O/R potential (oxygen amounts)

A

Sodium Thioglycollate

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25
Q

What is the meaning of the pink (red) color at the top of the tube of the medium FTM

A

An indicator for the presence of oxygen

26
Q

Name of the indicator dye in FTM and what does it detect

A

Resazurin which is an indicator for the presence of oxygen

27
Q

Why is FTM boiled before inoculation

A

To eliminate any oxygen present

28
Q

What are two enzymes lacking in and obligate anaerobe

A

Catalase and superoxide dismutase

29
Q

Where would you find obligate aerobic bacteria in the FTM? What environment does it prefer?

A

Towards the top of the FTM not in the middle or at the bottom. Must grow in oxygen

30
Q

Where would you find the microaerophiles in the FTM? What conditions do microaerophiles prefer?

A

A thin line In the middle of the tube. Not the top not at the bottom; prefers oxygen conc of 2 to 10% instead of the 20% found in the atmosphere

31
Q

Where would facultative anaerobes grow in FTM? What do they prefer?

A

They would grow throughout the tube. Metabolism is flexible so they can grow with or without oxygen present

32
Q

Where would anaerobic bacteria grow in FTM? What environment do they prefer?

A

Only at the bottom of the tube. Cannot tolerate oxygen

33
Q

Examples of obligate aerobes

A

Pseudomonas, Micrococcus, and many Bacillus

34
Q

Examples of a microaerophile

A

Helicobactor pylori

35
Q

Example of a facultative anaerobe

A

Escherichia coli

36
Q

Examples of aerotolerant anaerobes (also called obligate fermenters)

A

Enterococcus faecalis, Streptococcus pyogenes

37
Q

Examples of obligate anaerobes

A

Clostridium methanococcus and bacteroides

38
Q

Describe general-purpose media

A

Designed to grow a broad spectrum of microorganisms. Ex: TSA, TSB

39
Q

Describe enriched media

A

Contains an ingredient that will promote a robust growth of bacteria Ex: blood agar

40
Q

Describe selective media

A

Formulated to prevent the growth of certain bacteria but not others.
Ex: salt agar, manitol salt agar, macConkey agar

41
Q

Describe differential media

A

Designed to display visible differences among microorganisms

Ex: MSA, MAC

42
Q

The selective agents in SA, MSA, MAC

A 
SA= 10% salt
MSA= 7.5% salt
MAC= bile salts
43
Q

What are the differential agents in BA, MSA, MAC

A 
BA= blood
MSA= sugar (mannitol) and phenol red (pH indicator)
MAC= lactose and neutral red (pH indicator)
44
Q

Describe beta hemolysis

A

Complete hemolysis giving a clear zone with a clean edge around the colony

45
Q

Describe alpha hemolysis

A

Incomplete hemolysis producing a cloudy zone of greening around the colony due to the production of methemoglobin

46
Q

Describe gamma hemolysis

A

No hemolysis or no change in the blood around the colony

47
Q

PH indicator in MSA turns what color at what pH

A

Phenol red turns yellow around 6.8; means fermentation happened

48
Q

PH indicator in MAC turns what color at what pH

A

Neutral red changes from yellow to red around 6.8; means fermentation happened

49
Q

Which organisms do all three selective media select for

A

Salt (cocci)

50
Q

What organisms do all three selective media select against

A

Rods

51
Q

Which organisms were able to ferment mannitol

A

Staphylococcus aureus

52
Q

Which organisms were able to ferment lactose

A

E. coli

53
Q

What is the role of CaCl2

A

Neutralizes the cell membrane

54
Q

What is special about the MM 294 strain of E. coli

A

It is not resistant to ampicillin

55
Q

What is it meant to be competent

A

Ability to take up free DNA

56
Q

What is the source of DNA for transformation

A

P green plasmid

57
Q

What are the names of the two genes that are found on the P green plasmid

A

Gene for green fluorescent protein, gene for ampicillin resistance

58
Q

What proteins do the genes code for

A

Green fluorescent proteins and ampicillin resistance

59
Q

What is the purpose of the heat shock step during bacterial transformation

A

To open the Porins to allow the gene to enter

60
Q

What enzyme provides resistance to ampicillin

A

Beta lactamase

61
Q

What is the mode of action of the enzyme beta-lactamase

A

Breaks the beta lactam ring

62
Q

Describe The only plate with no growth

A

LBA/AMP agar; no p green; is the negative control

Completed (12 decks)

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