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Micobiology > Chapter 9 - The Study of Microbial Growth > Flashcards

Chapter 9 - The Study of Microbial Growth Flashcards

1
Q

Microbial growth occurs at what two levels?

A
  1. Growth at a cellular level with increase in size

2. Increase in population

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2
Q

Division of bacterial cells occurs mainly through ______ _______.

A

Binary fission

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3
Q

Time required for a complete fission cycle is called the __________, or ________ time.

A

Generation or doubling

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4
Q

Populations exhibit ___________ growth.

A

Exponential

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5
Q

Generation times vary from _______ to ____.

A

Minutes to days

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6
Q

What is the equation for calculating population size over time?

A

Nf = (Ni)2^n

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7
Q

What does Nf stand for in the equation for calculating the population size over time?

A

Total number of cells in the population

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8
Q

What does Ni stand for in the equation for calculating the population size over time?

A

Starting number of cells

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9
Q

What does the exponent n stand for in the equation for calculating the population size over time?

A

Denotes generation time

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10
Q

What does 2^n stand for in the equation for calculating the population size over time?

A

Number of cells in that generation

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11
Q

In laboratory studies, populations typically display a predictable pattern over time. What is this called?

A

Growth rate

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12
Q

What are the stages in the normal growth curve?

A
  1. Lag phase
  2. Exponential growth phase
  3. Stationary phase
  4. Death phase
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13
Q

What are the methods of analyzing population growth?

A
  1. Turbidometry

2. Enumeration of bacteria

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14
Q

What is enumeration of bacteria?

A
  1. Viable colony count
  2. Direct cell count
    • Using a cytometer
    • Using a Coulter Counter
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15
Q

How do you measure direct cell count?

A
  1. Using a cytometer

2. Using a Coulter Counter

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16
Q

What are environmental factors that affect the function of metabolic enzymes?

A
  • Temperature
  • Oxygen requirements
  • pH
  • Osmotic pressure
  • Barometric pressure
17
Q

Lowest temperature that permits a microbe’s growth and metabolism

A

Minimum temperature

18
Q

Highest temperature that permits a microbe’s growth and metabolism

A

Maximum temperature

19
Q

Promotes the fastest rate of growth and metabolism

A

Optimum temperature

20
Q

Optimum temperature below 15 degrees C; capable of growth at 0 degrees C

A

Psychrophiles

21
Q

Optimum temperature is 20 - 40 degrees C; most human pathogens

A

Mesophiles

22
Q

Optimum temperature greater than 45 degrees C

A

Thermophiles

23
Q
  • As it is utilized it is transformed into several toxic products
  • Most cells have developed enzymes that neutralize those chemicals
  • If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats
A

Oxygen

24
Q

What are the two categories of oxygen requirement?

A
  1. Aerobe

2. Anaerobe

25
Q
  • Obligate aerobe
  • Facultative anaerobe
  • Microaerophilic
A

Aerobe

26
Q
  • Obligate anaerobe

- Aerotolerant anaerobes

A

Anaerobe

27
Q

All microbes require some ______ _______ in their metabolism.

A

Carbon dioxide

28
Q

Grows best at higher CO2 tensions than normally present in the atmosphere

A

Capnophile

29
Q

Majority of microorganisms grow at a pH between __ and __

A

6 and 8

30
Q

What are the exceptions for those that grow at a pH between 6 and 8?

A
  • Obligate acidophiles

- Alkalinophiles

31
Q
  • Osmotic Pressure

Most microbes exist under _________ or ________ conditions

A

Hypotonic or isotonic

32
Q

What are the exceptions for those that exist in hypotonic or isotonic conditions?

A
  • Halophiles

- Osmotolerant

33
Q
  • Atmospheric Pressure

Most microbes live under ______ atmospheric pressures

A

Normal

34
Q

What is the exception for those that live under normal atmospheric pressure?

A

Barophiles

35
Q

What is an environmental factor that influences microbes?

A

Niche

Micobiology (15 decks)

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