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Microbiology Exam 1 > Lecture 9 > Flashcards

Lecture 9 Flashcards

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1
Q

How is growth measured for bacteria

A

Increase in the number of individuals

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2
Q

What is binary fission?

A

When one cell splits into two cells

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3
Q

How often doe binary fission happen?

A

Once every 20 minutes

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4
Q

T of F- The growth curve is not logarithmic

A

False, it is logarithmic

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5
Q

T or F- The growth curve count all cells

A

False, it only counts viable cells

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6
Q

What are the major phases of the growth curve?

A
  1. Lag Phase
  2. Log Growth Phase
  3. Stationary Phase
  4. Death Phase
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7
Q

Define the lag phase

A

It is the time that it takes for the organism to get used to its environment, has an increase in metabolism, and little to no cell division

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8
Q

Define the log growth phase

A

It is the point where the population actually starts doubling

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9
Q

When is a culture a young culture?

A

During the log growth phase

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10
Q

Define the stationary phase

A

Carrying capacity of the enviroment, with an equal number of cells dying as are dividing

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11
Q

When is a culture a mature culture?

A

In the stationary phase

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12
Q

Define the log death phase

A

Large number of individuals dying

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13
Q

When is a culture mature?

A

During the log death phase

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14
Q

What does cultural enumeration mean?

A

it means that you are growing out the colony

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15
Q

What is the CFU?

A

The colony forming unit, which is a single cell that will grow out into a colony

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16
Q

What is the name for the single cell that grows out into a colony?

A

The colony forming unit (CFU)

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17
Q

What are the direct plating methods?

A
  1. Colony Count Plating Method
  2. Enumeration
  3. Membrane Filter Method
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18
Q

Explain the colony count plating method

A

A serial dilution wherein you take 1mL of sample and dilute it into 9mL of water/saline. You repeat this process until the number of colonies on a plate is between 25-250

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19
Q

What does TNTC mean and when is it used?

A

‘Too numerous to count’, used where there are more than 250 colonies on a plate

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20
Q

Why is load important?

A

Load is important because the higher load you have (more bacteria) the more medication you need to give to the patient

21
Q

Why do we do serial dilutions?

A

To find out the load of the bacteria, which in turn tells us how much medication the patient needs

22
Q

What is the difference between the enumeration method and the colony count plating method?

A

The enumeration method only takes .1mL from the flask to determine the growth factor of the colony. CCP uses 1mL

23
Q

Define Membrane filter method

A

Used mostly for water samples that you would not expect much bacteria in. A filter membrane with small holes is placed to catch remaining bacteria

24
Q

How large are the holes in the filter of the membrane filter method?

A

About .2um, which results in clogging with highly contaminated samples

25
Q

Is the membrane filter method a direct or indirect method?

A

Direct

26
Q

What are the indirect methods for cultural enumeration?

A
  1. Most probable number
27
Q

Describe the Most Probable Method process

A

Get a major sample of bacteria and place 10mL in 5 tubes, 1mL in 5 tubes, and .1mL in 5 tubes. Inside each tube is a secondary tube that will trap the gasesm allowing you to calculate the number of bacteria in the original sample

28
Q

Do you count the individual colonies in the Most Probable method?

A

No

29
Q

How many tubes total are used in MPN method?

A

15, 5 with 10mL, 5 with 1mL, and 5 with .1mL

30
Q

Why do you use to many tubes in the MPN method?

A

To ensure accuracy

31
Q

What is the MPN method most comonly used for?

A

used to test for coliforms, such as e.coli, in water

32
Q

What test would you use to test for coliforms?

A

The Most Probable Number test (MPD)

33
Q

Name the non-cultural enumeration methods

A 
Direct:
1. Cytometer
2. Coulter counter
Indirect:
1. Total volume
2. Turbometric
34
Q

What are the direct noncultural enumeration methods?

A
  1. Cytometer

2. Coulter counter

35
Q

Is the MPN method direct or indirect?

A

Indirect

36
Q

Name the direct non-cultural enumeration methods

A
  1. Total volume

2. Turbometric

37
Q

Describe the cytometer count method

A

It is the gold standard for non-enumeration, and use you a gridded slide and count the number of bacteria that grow on it. It need to be standardized before use, and repeated if any of the count differ by 10% from other counts

38
Q

Cytometer is best used for what kind of samples?

A

Blood samples

39
Q

Describe the Coulter count method

A

A long electronic beam passes through a tube and is broken every time a bacteria passes through it. This needs to be standarized before use using the cytometer count method

40
Q

What method do you use to standardize the coulter count method?

A

The cytometer count method

41
Q

Describe the total volume method

A

You place the sample in a centrifuge, which results in the solids sitting at the bottom of the tube, can be done in 5 minutes, and need to be standardized using the colony count plate method

42
Q

What do you use to standardize the total volume method?

A

The colony count plate method

43
Q

What is the total volume method commonly used for?

A

Beer

44
Q

How long does a total volume method normally take?

A

About 5 minutes

45
Q

Describe the turbometric method

A

You shine a light through your sample and measure how much is absorbed. The more that is absorbed, the more bacteria there is. This needs to be standardized

46
Q

You are using the turbometric method, and find that a lot of light shines through your sample. What does this mean?

A

It means you don’t have a lot of bacteria in that sample

47
Q

The the total volume method a cultural enumeration method or a noncultural enumeration method?

A

noncultural enumeration method

48
Q

How can you tell how much bacteria you have in a most probable number method?

A

Each tube has a secondary tube inside of it that captures the CO2 produced by the bacteria in the sample

Microbiology Exam 1 (13 decks)

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