Exam 2 (Ch. 6 Microbial Growth) Flashcards Preview

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Flashcards in Exam 2 (Ch. 6 Microbial Growth) Deck (74):
1

Growth (def.)

increase in number of cells

2

colonies

groups of cells that can be seen without a microscope

3

what does CFU stand for

colony forming units

4

another name for colony forming units is

colony

5

things needed for growing microbes (4 things)

1. chemical needs for microbe must be determined-media (what do they eat)
2. media is made and sterilized (autoclaved)
3. microbe is inoculated into media
4. inoculated media is placed in proper env't (temp, pH, oxygen, light, etc.)

6

autoclave (def.)

heat under pressure for 20 min.

7

culture (def.)

microbe growing on the media

8

inoculate (def.)

process of adding/ introducing microbes to the media

9

incubate (def.)

the appropriate time and temp to grow the specific bacteria

10

enrichment culture (def.)

set of conditions such as temp, pH, salinity, light, nutrients, and oxygen that are tailored to requirements of desired microbe

11

pure culture (def.)

one type of microbe

12

mixed culture (def.)

2 or more types of microbes

13

how many zones are created to isolate pure colonies

four

14

zone one has the fewest _____ colonies and zone four has the most

isolated

15

zone four has the most______colonies

isolated

16

culture media (def.)

nutrient material made for the growth of microbes (food)

17

nutrient broth (def.)

liquid media

18

agar (def.) (3 things)

1. solidifying agent
2.liquid at 100 degrees C
3. solid at 40 degrees C

19

complex media (def. and ex.)

media that uses substances where precise contents are unknown. ex: yeast extract, casein, beef extract, etc.)

20

chemically defined media (def.)

exat chemical composition is known

21

selective media (def. and ex.)

designed to encourage only growth of desired microbe,
ex: sabouraud agar pH of 5.6 to grow fungi

22

differential media (def. and ex.)

contains substances that allow different microbes to be identified growing on the same media, ex: S. aureus growing on MSA turns the agar from red to yellow when present

23

MSA tands for

mannitol salt agar

24

carbon (2 things)

1. most abundant element
2. used to make carbs, proteins, lipids, and nucleic acids

25

name 4 organic compounds

carbs, proteins, lipids, nucleic acids

26

4 chemical requirements for growth

nitrogen, phosphorus, sulfur, trace elements

27

nitrogen (3 things)

1. 2nd most abundant element
2. used to make proteins and nucleic acids
3. found in nature as ammonia, N2 gas, or nitrate

28

phosphorus

used to make DNA, RNA, ATP, and phospholipids

29

sulfur

used to make vitamins and amino acids

30

trace elements (def. and ex.)

needed in small amounts for enzymes to function, ex: Fe, Cu, Zn, Mg

31

aerobe (def.)

uses oxygen

32

anaerobe (def.)

doesn't use oxygen

33

obligate aerobe (def. and ex.)

must have oxygen, ex: Micrococcus luteus

34

obligate anaerobe (def. and ex.)

dies in the presence of oxygen, ex: Clostridium tetani

35

facultative anaerobe (def. and ex.)

uses oxygen when present but can grow without it,
ex: E. coli

36

aerotolerant anaerobe (def. and ex.)

can survive in presence of oxygen but grows better without it, ex: Lactobacillus

37

cardinal temperatures (def.)

min., opt., and max. temperatures

38

minimum temperature (def.)

lowest temperature at which growth will occur

39

optimum temperature (def.)

temp at which growth is most rapid

40

maximum temperature (def.)

highest temp. at which growth will occur

41

psychrophile (5 things)

1. cold-loving
2. can grow at 0 degrees C
3. opt. below 5-15 degrees C
4. found in glaciers and deep in ocean
5. ex: Polaromonas vacuolata

42

psychrotroph (2 things)

1. optimum 20-30 degrees C
2. ex: Staphlococcus aureus (food spoiler)

43

mesophile (5 things)

1. moderate temp. loving
2. 25-40 degrees C
3. most common
4. found in animals, soil and water
5. ex: E. coli

44

thermophile (4 things)

1. heat loving
2. opt. 50-60 degrees C
3. found in volcanoes, hydrothermal vents and hot springs
4. ex: Thermus aquaticus

45

acidophile (3 things)

1. opt. pH below 6.5
2. found in areas with sulfuric or hydrochloric acid (hot springs)
3. ex: fungi, Helicobacter pylori, Lactobacillus

46

Helicobacter pylori

likes to live in your stomach and can cause ulcers

47

alkaliphiles (3 things)

1. opt. pH above 8
2. found in soda lakes
3. ex: Bacillus alkalophilus

48

neutrophiles (2 things)

1. opt. pH 7
2. most bacteria are in this category

49

halophiles (3 things)

1. require high salt concentration
2. found in Dead Sea or Great Salt Lake
3. ex: Halococcus

50

growth requirements for most microbes (3 things)

1. mesophiles
2. pH (neutral) 7
3. little salt

51

plate count (2 things)

1. most common method
2. measures number of viable cells

52

serial dilution (explain)

bacteria are added to tubes at varying dilutions, poured into plates, allowed to grow

53

a plate with the highest dilution will have the _______ amount of bacteria (growth)

least

54

pour plate method (5 things)

1. bacteria added to liquid agar
2. mixture poured into empty plates
3. agar solidifies, plate incubated
4. colonies grow within and on surface of agar
5. plates with 30-300 colonies are used to calculate original cell concentration

55

spread plate method (3 things)

1. bacteria added to solid agar
2. spread over surface of agar with sterile rod
3. colonies only on surface of agar

56

direct microscopic count (def.)

look through a microscope and count the number of bacteria

57

Pros of direct microscopic count

no incubation time (fast) and cheap

58

Cons of direct microscopic count

dead cells are counted

59

2 types of plate counts

pour plate and spread plate

60

4 types of measurement for microbial growth

1. plate count
2. direct microscopic count
3. turbidity
4. most probable number

61

MPN stands for

most probable number

62

turbidity (4 things)

1. more bacteria in liquid culture means more turbid (cloudy)
2. beam of light passes through the test tube
3. more bacteria, less light will pass through
4. uses spectrophotometer

63

most probable number (MPN) (5 things)

1. used when plate counts aren't reliable
2. estimates number of microbes in original sample using a serial dilution
3. positive results seen by gas production
4. a table estimates the number of microbes in original sample
5. used in testing water purity

64

generation

1 cell dividing into 2

65

generation time

time it takes for the population size to double

66

growth curve (3 things)

1. graph that plots growth of a population
2. used to calculate generation time
3. uses logarithmic scale

67

4 phases of growth, in order

lag phase, log or exponential phase, stationary phase, death phase

68

lag phase (2 things)

1. period of adjustment
2. slow growth

69

log or exponential phase

population is doubling

70

stationary phase (2 things)

1. equal number of cells dividing and dying
2. due to depletion of nutrients, accumulation of waste, drop in pH

71

death phase

cells are dying

72

2 ways of preserving bacterial cultures

flash-freezing and lyophilization

73

flash-freezing

pure culture of bacteria are quickly frozen at -50 to -95 degrees Celsius

74

lyophilization (4 things)

1. pure culture is flash frozen
2. vacuum is used to remove water
3. result is powder residue
4. bacteria revived by adding liquid media