Microbio Chapter 6- Microbial Growth Flashcards
(112 cards)
1
Q
What factors determine growth of prokaryotes?
A
Temperature
pH
Osmotic pressure
Oxygen
2
Q
Which of the growth factors are physical factors?
A
Temperature
pH
Osmotic pressure
3
Q
Which of the growth factors is a chemical factor?
A
Oxygen
4
Q
What are the three primary groups made on the basis of their preferred temperature?
A
- Psychrophiles
- Mesophiles
- Thermophiles
5
Q
What general temperature do psychrophiles prefer?
A
Cold temps
6
Q
What general temperature do mesophiles prefer?
A
Moderate temps
7
Q
What general temperature do thermophiles prefer?
A
Hot temps
8
Q
What are the two divisions of psychrophiles?
A
True
Pyschotrophs
9
Q
What temperature can True psychrophiles start to grow?
A
0 degrees celsius
10
Q
What is true psychrophiles optimum temperature?
A
15 degrees celsius
11
Q
What temperature can true psychrophiles not grow at?
A
20-25 degrees celsius
12
Q
Do true psychrophiles cause disease?
A
No they are non-pathogenic
13
Q
What is the other name for pyschrotrophs?
A
Falcutative
14
Q
What temperature can pyschrotrophs start to grow?
A
0 degrees celsius
15
Q
What is pychrotrophs optimum temperature?
A
20-30 degrees celsius
16
Q
What temperature can pyschrotrophs not grow at?
A
30 degrees celsius
17
Q
What do Psychrotrophs often cause?
A
Food spoilage even when refrigerated its just slowly degrades food
-mold, odour,slime
18
Q
What temperatures can Mesophiles start to grow?
A
25-40 degrees celsius
19
Q
What is Mesophile sotimum temperature?
A
37 degrees celsius
20
Q
What temperature can Mesophiles not grow?
A
50 degrees celsius
21
Q
Are Mesophiles disease causing?
A
Yes they are pathogens
22
Q
What are the two types of Thermophiles?
A
Thermophiles
Hyperthermophiles
23
Q
What temperature can thermophiles NOT grow at?
A
Any temperature below 45 degrees celsius
24
Q
What are thermophiles optimum temperature?
A
50-60 degrees celsius
25
What is the maximum temperature thermophiles can grow at?
70-80 degrees celsius
26
Are thermophiles disease causing?
No, they are non-pathogenic
27
What temperature can hyperthermophiles NOT grow at?
Any temperature below 45 degrees celsius (same as thermophiles)
28
What are hyperthermophiles optimum temperature?
50-60 degrees celsius (same as thermophiles)
29
What is the maximum temperature hyperthermophiles can grow at?
110-121 degrees celsius
30
Are hyperthermophiles disease causing?
No, they are non-pathogenic
31
how does pH affect prokaryotes growth?
Too basic or too acidic will denature stop the bacteria from growing
32
What the pH range that most bacteria grow best in?
ph 6.5- 7.5 (neutral)
33
What are acidophiles?
Bacteria tolerable to acidity (low pH)
34
How does osmotic pressure affect cell growth?
Too little or too high concentrations of solute concentrations can inhibit growth
35
How does a hypertonic environment affect cell growth?
The solution/environment has higher concentration of solutes then inside the cell causes water to leave the cell and makes the cell shrink
36
What is isotonic?
Solute concentration outside the cell is equivalent to the solute concentration inside the cell
37
What is hypotonic?
Solute concentration outside the cell is lower than the solute concentration inside the cell
38
How do hypotonic/ low osmotic pressure affect cell growth?
Water enters the cell and microbes with weak cell walls with be lysed 9prevent growth)
39
How do high concentrations of sugar or salt affect cell growth?
Increase osmotic pressure = hypertonic
Water leaves the cell and prevent growth
40
How does energy extraction differ between aerobes and anaerobes?
Aerobes (use oxygen) extract more energy from nutrients
41
What are organisms that require oxygen for growth called?
Obligate aerobes
42
What enzymes do obligate aerobes have present?
Enzymes catalase and SOD
43
What does enzymes catalase and SOD do?
Neutralize toxic forms of oxygen
44
What are organisms that are anaerobic and aerobic called?
Facultative Anaerobes
45
Where do facultative anaerobes have greater growth?
In the presence of oxygen
46
What enzymes do facultative anaerobes have present?
Enzymes catalase and SOD
47
What is the name of organisms who only grow in the absence of oxygen?
Obligate Anaerobes
48
What enzymes do obligate anaerobes have present?
NO enzymes
-cannot tolerate any form of oxygen
49
What is the name of organisms who only grow in anaerobically but growth will continue in presence of oxygen?
Aerotolerant Anaerobes
50
What enzyme do aerotolerant anaerobes have present?
Only SOD
51
What occurs if only one enzyme is present?
Toxic forms of oxygen are partially neutralised
52
What are organisms called that only grow in low oxygen concentrations?
Microaerophiles
53
What happens if Microaerophiles are exposed to normal atmospheric oxygen?
They will produce lethal amounts of toxic forms of oxygen
54
What bacteria are obligate aerobes?
Most bacteria
55
What bacteria are obligate anaerobes?
Clostridium
56
What is an example of a facultative anaerobe?
Escheria coli
57
What kind of respiration do Aerotolerant anaerobes use?
Fermentation
-Obligate fermenters
58
What is an example of an Aerotolerant anaerobe?
Lactobacilli
59
What are example of microaerophiles?
Helicobacter pylori
Complyobacter jejuni
60
What does Helicobacter pylori cause?
Stomach ulcers
61
What does Complyobacter jejuni cause?
Gastroenterillis
62
What are the toxic oxygen forms?
Singlet oxygen 1O2-
Superoxide Radicals or Anions (free radicals) O2-
Peroxide anion O2 2-
Hydroxyl radical OH-
63
What is singlet oxygen?
Normal molecular oxygen that has been boosted into a higher-energy state
-Extremely reactive
64
What are superoxide free radicals?
Very unstable (Steals electrons from neighbouring molecules and becomes a radical)
65
What neutralises Superoide free radicals?
SOD: Superoxide dismutase
66
What bacteria have SOD?
Obligate aerobes
Facultative anaerobes (when growing aerobically)
Aerotolerant anaerobes
67
How does SOD neutralise superoxide free radicals?
SOD converts superoxide radical into molecular oxygen (O2) and hydrogen peroxide (H2O2)
68
What is the reaction equation for SOD neutralising superoxide radicals?
O2- + O2- + 2H+ ---> H2O2 + O2
69
How are superoxide radicals produced?
Formed in small amounts during normal aerobic respiration or by obligate anaerobes in the presence of oxygen
70
How are peroxide anions formed?
The hydrogen peroxide produced during the neutralisation of Superoxide radicals by SOD contains peroxide anions (produced during aerobic respiration)
71
What has peroxide anions as an active principle?
Antimicrobial agents
e.g, Hydrogen peroxide and benzoyl peroxide
72
What enzymes neutralises peroxide anions?
Enzyme catalase and peroxidase
73
How does catalase neutralise peroxide anions?
Converts it into water and oxygen
74
How does peroxidase neutralise peroxide anions?
Converts it into only water (no oxygen)
75
What is the reaction equation for catalase?
2 H2O2 ---> 2H2O + O2
76
What is the reaction equation for peroxidase?
H2O2 + 2H+ ---> 2H2O
77
How are hydroxyl radicals formed?
Ionizing radiation and trace amounts are produced by most aerobic respiration
78
What is the most reactive form of toxic oxygen?
Hydroxyl Radicals (OH)
79
How are toxic oxygen forms important to phagocytosis?
When Phagocytes ingest pathogens the toxic forms kill them
80
What is used to grow bacteria on a solid medium?
Nutrient agar
81
At what temperature does Agar liquify?
100 degrees celsius
82
At what temperature does Agar solidify?
37 degrees celsius
83
What happens when the Agar is heated to 100 degrees?
Sterilization
84
Why is sterilisation important fro culture media?
Allows it to be stored for longer periods
85
Why is agar used?
Bacteria cannot metabolise it
86
What is the name of the method when agar is used?
Streak plate method
87
Why is the streak plate method used?
Isolates pure cultures
-Specific
88
What is a pure culture?
Contains only one species or strain
89
What is the tube/broth method?
Bacteria is grown in a nutrient broth in a test tube
90
What are the pros and cons of the broth method?
Pro- Grows quickly
Con- Less specific (Can't make a diagnosis
91
What are the kinds of media?
Selective media
Differential media
Selective and Differential media
92
What agar is used for selective media?
Bismuth sulfite agar
93
What is the purpose of selective media?
Supresses unwanted microbes and encourages desired microbes
-only one colony appears
94
What is an example of a bacteria encouraged to grow by selective media?
Salmonella typhus
95
What does Salmonella typhus cause?
Typhoid fever
96
What agar is used for differential media?
Blood agar
97
What is the purpose of differential media?
Makes it easy to distinguish colonies of different microbes on the same plate
98
What is an example of bacteria grown using differential media?
Streptococcus pyogenes
Invasive group A
99
What does Streptococcus pyogenes cause?
Strep throat
100
Why is blood agarused?
It contains RBC and can detect bacteria that lyses blood cells (Hemolysis)
Hemolysis will result in a clear zone
101
What agar is used for selective and differential media?
Mannitol salt agar
102
What is the purpose of using selective and differential media?
You suppress unwanted microbes and can distinguish colonies
103
What is an example of bacteria grown using selective and differential media?
Staphylococcus aureus
104
What does Staphylococcus aureus cause?
Skin infections, toxic shock and food poisoning
105
what is binary fission?
method of cell division for microbial growth
106
What is generation time?
Time required for a cell to divide (population doubles)
107
What is the formula for generation time?
60 min x Hours / number of generations
108
What is the lag phase?
Phase #1
Intense activity, population prepares for growth
no growth actually occurs
109
What is log phase?
Phase #2
Logarithmic increase in population
Binary fission occurs
110
What is the stationary phase?
Phase #3
Equilibrium
Microbial deaths are equal to production of new cells
111
What is the death phase?
Phase #4
Logarithmic decline
Population decreases at logarithmic rate
112
