Chapter 6 Growth and Culturing of Bacteria

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Microbiology
Chapter 6
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1

the increase in the number of cells, which occurs by cell division

microbial growth

2

Bacteria generally divide by which two ways

1. binary fission
2. budding

3

Which cell (prokaryotic or eukaryotic) follow a cell cycle?

eukaryotic

4

How many circular chromosomes do most bacteria have?

one

5

What are the phases of growth found in standard bacterial growth curves

1. lag phase
2. log phase
3. stationary phase
4. decline (death) phase

6

phase of bacterial growth where cells are actively producing ATP preparing for cell division

lag phase

7

phase of bacterial growth that is the period of greatest cell division

log phase

8

the time required for a population of cells to double

generation time

9

new cells are produced very near the rate at which cells die; cells begin to die due to a build-up of waste products and possible shortages of nutrients, oxygen, and water

stationary phase

10

fewer cells are able to divide and more and more cells die as conditions degrade

decline (death) phase

11

when cells exhibit unusual shapes [many cells may undergo this in decline (death) phase]

involution

12

in decline (death) phase some genera of bacteria produce these for survival

endospores

13

generally formed when a single cell divides to produce a large number of cells

colony

14

all of the cells in a colony descend from a single what?

cell

15

How does a colony grow?

slower in the center and faster at the edges

16

Cells at the edges have a better advantage because of what?

because they have greater access to fresh nutrients and water and fewer waste products are located there

17

give three characteristics of E. Coli

* plump bacillus
* Gram -
* motile (peritrichous)

18

what is so bad about the killer strain of E. Coli 0157 H7

it shuts down kidneys and secretes intotoxins while alive

19

What is the generation time for the killer strain of E. Coli 0157 H7

22 minutes

20

prefers to grow where no oxygen is present but is able to adjust to and tolerate the environmental condition, but it can also live in other conditions

facultative anaerobe

21

list five ways to measure bacterial growth

1. serial dilution and plate count
2. direct microscopic count
3. most probable number
4. filtration
5. turbidity (cloudiness)

22

this type of bacteria grows at the bottom of a solid medium

anaerobe

23

all cells remain on the surface of the solid medium (aerobe)

spread plate

24

this method is used if you are not sure if it is aerobe or anaerobe

pour plate

25

30 to 300 per plate

countable number

26

begins with an estimate, then dilutions and plates

most probable number

27

cloudiness

turbidity

28

allows the cells in a sample to be dried and then weighed

dry weight measurement

29

the measurement of metabolic products in a sample can also be used indirectly to do what?

measure bacterial growth

30

what are the two major factors affecting bacterial growth

1. Physical factors
2. Nutritional factors

31

What are the physical factors affecting bacterial growth?

* pH
* temperatures
* oxygen concentration
* moisture
* hydrostatic pressure
* osmotic pressure
* radiation

32

examples of bacteria that grow best at their optimum pH.

acidophiles
neutrophiles
alkaliphiles

33

Examples of bacteria that grow better at extreme or different body temperatures

psychrophiles
mesophiles
thermophiles

34

examples of major groups of aerobes and anaerobes that affect bacterial growth

obligate aerobe
obligate anaerobe
microaerophile
facultative anaerobe
aerotolerant anaerobe

35

most vegetative cells can live only a few hours without this physical factor that affects bacterial growth

moisture

36

physical factor that affects bacterial growth that is exerted by standing water

hydrostatic pressure

37

salt-loving organisms

halophiles

38

As far as nutritional facts are concerned what factors affect bacterial growth

SPONCH (sulfur, phosphorus, oxygen, nitrogen, carbon, hydrogen)
trace elements
nutritional complexity

39

some bacteria have special nutritional requirements and makes them hard to grow in a laboratory. These bacteria are known as what?

fastidious

40

elements that are required in very small amounts are ions and are needed as cofactors

trace elements

41

The type of enzymes and the number of enzymes present determine the what of an organism which normally has fewer types and numbers or enzymes than less nutritionally complex organisms

nutritional complexity

42

bacterial interactions affecting growth explain some peculiar adaptive aspects of bacterial bioluminescence

quorum sensing

43

acts as a kind of "superorganism" with different cells responding differently within it

biofilm

44

the formation of endospores

sporulation

45

two genera known for producing endospores

Bacillus and Clostridium

46

normally produced due to deteriorating environmental conditions

endospores

47

The core (which consists of what) of an endospore contains what is needed to return to a vegetative cell when conditions improve

cytoplasm
DNA
ribosomes
enzymes

48

What are the two methods of obtaining pure cultures

streak plate method
pour plate method

49

method of obtaining pure cultures that uses agar plates

streak plate method

50

method of obtaining pure cultures that makes use of serial dilution

pour plate method

51

When we classify agar it can be what or what?

Natural or Synthetic

52

What are examples of natural culture media?

soil
water
living tissue

53

type of culture media that is classified by chemical make up

synthetic (defined or complex)

54

type of synthetic culture media that the ingredients and exact amounts are known

defined

55

type of synthetic culture media that the ingredients are known, but the exact amounts may vary from batch to batch

complex

56

type of culture media that is classified by how the agars are used

selective
differential
enrichment

57

type of culture media that encourages one species and discourages others

selective

58

type of culture media that you can see a pH or color change in

differential

59

type of culture media that has extra vitamins and minerals added to it

enrichment

60

minimize the chances that culture will be contaminated by organisms from the environment or that organisms, especially pathogens, will escape into the environment

asceptic techniques

61

what are the three ways to maintain cultures

stock cultures
preserved cultures
reference culture

62

a way to maintian cultures (not used for lab cultures) a pure culture that can be maintained indefinetly once an organism has been isolated

stock culture

63

a way to maintain cultures that is a culture in which organisms are maintained in a dormant state

preserved culture

64

a preserved culture that maintains the organisms with the characteristics as originally defined

reference cultures

65

What is involution?

cells assume a variety of unusual shapes, which makes them difficult to identify (starts when the cell starts to die- death/decline phase)

66

Name at least two ways to measure bacterial growth

(any of the two will work)
serial dilutions & plate count; filtration; turbidity; most probable number; direct microscope count

67

What is meant by "generation time"?

the time required for a population of cells to double (can vary) (asyncronous)

68

What is selective medium?

one that encourages the growth of some organisms but supresses the growth of others

69

How do we obtain pure cultures? (the book listed two ways)

streak plate method
serial dilution and pour plate method

70

cell division in bacteria is primarily by the process of what?

binary fission

71

Cell division in yeast occurs primarily by what?

budding

72

The bacterial growth curve is divided into how many phases?

4 [lag, log, stationary, and decline (death)]

73

Lag phase is characterized by what

a great decrease in cell number

74

In stationary phase what happens to cell populations numbers?

they remain static

75

Endospores are most likely to be produced in great numbers in what?

stationary phase

76

The solidifying agent most commonly used in microbiological media is what?

agar

77

the appropriate number of colonies to count when performing plate counts is

30 - 300

78

Most of the bacteria that cause disease in humans are _______.

neutrophiles

79

Bacteria that prefers to grow between 25C and 40C are termed

mesophiles

80

An organism that prefers high concentrations of carbon dioxide is termed a _____.

capnophile

81

An aerotolerant anaerobe:

requires low concentration of oxygen

82

The enzyme responsible for the breakdown of peroxide to water and oxygen is called ______.

catalase

83

A halophile requires high what for growth?

salt concentrations

84

Bacteria that are difficult to cultivate due to special nutritional needs are termed what?

fastidious

85

The process of an endospore becoming a vegetative bacterium is called what?

germination

86

The spore coat is composed primarily of what?

lipid

87

MacConkey agar is what?

both selective and differential

88

A culture that has been freeze-dried is termed

lyophilized

89

Culture media that allows some microbes to grow but suppresses others is what?

selective media