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IOE Dentistry - Oral Microbiology > Environmental Conditions Affecting the Oral Microbiota > Flashcards

Environmental Conditions Affecting the Oral Microbiota Flashcards

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Biology 101 flashcards
1
Q

How to bacteria replicate?

A

Reproduce asexually via binary fission

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2
Q

Briefly describe binary fission

A

Cells circular DNA replicates
Divison of cytoplasm membrane and cell wall follows
Basically the cell splits into 2 daughter cells

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3
Q

How do viruses replicate?

A

They dont posses the necessary ‘machinery’ to reproduce on their own so they must latch onto a host cell
This allows viruses to use the host cells own cytoplasmic material to synthesise viral components
They are non-cellular organism

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4
Q

Why are viruses described as being non-cellular

A

Because they are made of nucleic acids (DNA OR RNA)
This nucleic avis is enveloped
It is non-cellular as it doesn’t have a phospholipid membrane

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5
Q

How do yeast cells replicate?

A

Budding
This is a form of asexually reproduction where a new organism develops from a bud as cell division occurs at a specific site of that cell

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6
Q

How can we measure growth of cells?

A

Estimate the increase in:

  1. The number of cells
  2. The dry mass (dry weight)
  3. The cellular constituents (eg the increase in ATP)
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7
Q

How can we measure population size?

A
  1. Total counts using microscopy

2. Viable counts using colony forming units

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8
Q

Describe the total count method?

A

Can do a total count using a microscope and a special glass slide called the counting chambers
These counting chambers lets you count the cells in a chamber using a microscope
You can count the number of cells in a chamber and then estimate the total number of organism in the whole population

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9
Q

What is a downside to the total count method?

A

It does not discriminate between living and dead cells

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10
Q

What is the viable count method?

A

Allows for the estimation of the living cells in a population

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11
Q

What do you need to be able to successfully cultivate viruses?

A

You require a living host cell to support viral replication

You can use eggs, mammillary cell, prokaryotic cells

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12
Q

If bacterial colonies on agar appear identical what does this suggest?

A

They are the same organisms

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13
Q

If bacterial colonies on agar appear distinct what does this suggest?

A

They are different species

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14
Q

What are the 4 stages in a bacterial growth curve

A
  1. Lag phase
  2. Log exponential phase
  3. Stationary phase
  4. Death/decline phase
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15
Q

What is on the y axis on a bacterial growth curve

A

Log10 colony forming units (CFU)

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16
Q

When does the growth of micro organism change?

A

When the environmental factors affecting bacterial growth change

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17
Q

What are some environmental facts that can influence bacterial growth?

A 
Host defences
Availability of nutrients 
Temperature
Oxygen/redox potential 
pH
Antimicrobial compounds
Oxygen, Ph, metabolic product gradients 
Depends on the site of the mouth the bacteria may be in
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18
Q

What are the 3 categories microbes can be grouped into depending on their optimum temperature?

A
  1. Psychrophiles grow best at 20 degrees
  2. Mesophiles grow best at 35 degrees
  3. Thermophiles grow best at 65 degrees
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19
Q

What can the temperature rise to when inflammation occurs and what can this do

A

Can inverse to 39 degrees and this has an effect on the microbial populations

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20
Q

What are the 5 categories microbes can be grouped into depending on their optimum oxygen concentrations?

A

Obligate aerobe: they require the precedes of oxygen to survive
Facultative anaerobe: they are able to grow in both the precedes and absence of oxygen
Microaerophile: require some levels of atomospheric oxygen
Aerotolerant anaerobe: The bacteria require the absence of oxygen but can tolerate oxygen
Obligate anaerobe
Require the complete absence of oxygen

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21
Q

What are obligate anaerobes?

A

They are highly sensitive to oxygen
They generate energy without oxygen
They Require sites with low redox potential

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22
Q

What type of environment is the mouth in regard to oxygen levels?

A

Quite aerobic environment

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23
Q

What are the 5 reactive oxygen species?

A 
Molecular oxygen is not toxic but its derivatives are:
Singlet oxygen 
Peroxide anion 
Superoxide anion 
Hydroxyl free radical
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24
Q

How are the derivatives of oxygen formed?

A

They are by products of cellular metabolism

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25
Q

What do detoxifying enzymes do?

A

Detoxuify the derivatives of oxygen making them less toxic

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26
Q

What are the 3 examples of detoxifying enzymes?

A
  1. Superoxide dismutase
  2. Peroxidase
  3. Catalase
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27
Q

What does Catalase catalyse?

A

The breakdown of hydrogen peroxide to water and oxygen

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28
Q

What does Superoxide dismutase do?

A

Breakdown the superoxide anion into hydrogen peroxide and oxygen

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29
Q

What does Peroxidase do?

A

Catalyses the breakdown of hydrogen peroxide into water

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30
Q

What is the redox potential and what is it symbolised by?

A

It is the tendency of a solution to take or give up electrons
Symbolised by Eh
Measured in millivolts

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31
Q

What does a high redox potential mean?

A

It means the solution has a greater tendency to gain electrons and to be reduced

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32
Q

What happens to the redox potential as plaque develops?

A

The redox potential decreases from 200mV to -141mV in about a week

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33
Q

What happens to the redox potential in the gingival crevice when gingivitis occurs?

A

The redox potential decreases from 73mV to -48mV this is due to a change in the local conditions (increased temp etc)

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34
Q

What are the 3 categories microbes can be grouped into depending on their optimum pH levels?

A

Acidophiles: thrive at acidic pH
Neutrophiles: thrive at neutral pH
Alkalophiles: thrive at alkaline pH

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35
Q

What does it mean if an organism is aciduric?

A

It can survive and grow at low pHs

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36
Q

What process breaks down glucose and what is it broken down into?

A

Glycolysis is the breakdown of glucose into PYRUVATE

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37
Q

What are the 2 substance pyruvate is broken down into>

A

If carbohydrates are limited pyruvate breaks down into ACETATE, FORMATE and ETHANOL (heterofermentation)

If carbohydrates are in excess pyruvate breaks down into lactate
(Homofermentation)

38
Q

What are endogenous nutrients?

A

Molecules and proteins produced by the host cells and that can be metabolised by microbiota

39
Q

Give some examples of some endogenous nutrients

A

Mucin in saliva

GCF components

40
Q

What are exogenous nutrients?

A

Molecules and proteins coming from outside the body eg from the food we eat

41
Q

What happens when endogenous mucin Is metabolised?

A

Slow rate of acid production causing a small fall in pH

42
Q

What happens when endogenous GCF Is metabolised?

A

Causes a rise in pH

43
Q

What happens when exogenous sucrose Is metabolised?

A

Rapid rate of acid production causing a terminally low pH (potentially lower than 5)

44
Q

What is the name of the group of bacteria that grow best at 20 degrees?

A

Psychrophiles

45
Q

What does a low redox potential mean?

A

It means the solution has a greater tendency to lose electrons and to be oxidised

46
Q

What is heterofermentation?

A

Breakdown of pyruvate into ACETATE, FORMATE and ETHANOL

This happens when carbohydrates limited

47
Q

Which enzyme breaks down hydrogen peroxide into water and oxygen

A

Catalase

48
Q

What is glycolysis?

A

The breakdown of glucose into pyruvate

49
Q

What is the name of the group of bacteria that grow best at 65 degrees?

A

Thermophiles

50
Q

Which enzyme breaks down superoxide anions into hydrogen peroxide and oxygen

A

Superoxide dismutase

51
Q

What is pyruvate broken down into when carbohydrates are limited

A

ACETATE, FORMATE and ETHANOL

This process is called heterofermentation

52
Q

What is the name of the group of bacteria that grow best at 35 degrees?

A

Mesophiles

53
Q

Which enzyme breaks down hydrogen peroxide into water

A

Peroxidase

54
Q

What is homorofermentation?

A

Breakdown of pyruvate into lactate

This happens when carbohydrates are in excess

55
Q

What is it called if an organism can survive and grow at low pHs?

A

Aciduric

56
Q

What is pyruvate broken down into when carbohydrate are in excess?

A

Lactate

This process is called homofermentation

57
Q

What is the name of the group of bacteria that grow best at 65 degrees?

A

Thermophiles

58
Q

Psychrophiles grow best at what temperature?

A

20 degrees

59
Q

Obligate aerobe grow best at what oxygen level?

A

They require the precedes of oxygen to survive

60
Q

Facultative anaerobe grow best at what oxygen level?

A

They are able to grow in both the precedes and absence of oxygen

61
Q

Mesophiles grow best at what temperature?

A

35 Degrees

62
Q

Microaerophile grow best at what oxygen level?

A

require some levels of atmospheric oxygen

63
Q

Thermophiles grow best at what temperature?

A

65 Degrees

64
Q

Aerotolerant anaerobe grow best at what oxygen level?

A

The bacteria require the absence of oxygen but can tolerate oxygen

65
Q

Obligate anaerobe grow best at what oxygen level?

A

Require the complete absence of oxygen

66
Q

Give examples of micro organisms that favour neutrality?

A

S. sanguinis Actinomyces naeslundii, Neisseria etc

67
Q

Give examples of micro organisms that are acidogenic?

A

S. mutans
Lactobacilli;
(inhibits “health-associated” species)

68
Q

Give examples of micro organisms that are Alkalophiles?

A 
Porphyromonas gingivalis
(implicated in periodontal diseases)
69
Q

How can we control microbial growth ?

A

Via knowledge of their:

  1. physiology and growth
  2. ecology
  3. using external chemicals
  4. using physical agent
70
Q

Which functions can antibiotics affect to try and kill bacteria?

A
  1. Cell wall synthesis
  2. DNA replication
  3. Protein synthesis
  4. Membrane function
  5. Synthesis of essential metabolites
71
Q

Which antibiotics affect the cell wall synthesis of bacteria?

A

Penicillins
Cephalosporins
Vancomycin

72
Q

Which antibiotics affect the DNA replication and transcription of bacteria?

A

Quinolones

Rifampin

73
Q

Which antibiotics affect the protein synthesis of bacteria?

A

Chloramphenicol
Tetracyclines
Erythromycin
Aminoglycosides

74
Q

Which antibiotics affect the membrane function of bacteria?

A

Polymyxin B

Nystatin

75
Q

Which antibiotics affect the the synthesis of essential metabolites of bacteria?

A

Trimethoprim

Sulfonamides

76
Q

Which antibiotic is most commonly used in dentistry and what does it target

A

Metronidazole

Works against anaerobes

77
Q

Penicillins affects what part of the bacteria?

A

Cell wall synthesis

78
Q

Trimethoprim affects what part of the bacteria?

A

Synthesis of essential metabolites

79
Q

Tetracyclines what part of the bacteria?

A

Protein synthesis

80
Q

Polymyxin B affects what part of the bacteria?

A

Membrane function

81
Q

Vancomycin affects what part of the bacteria?

A

cell wall synthesis

82
Q

Chloramphenicol affects what part of the bacteria?

A

Protein synthesis

83
Q

Quinolones affects what part of the bacteria?

A

DNA replication and transcription

84
Q

Erythromycin affects what part of the bacteria?

A

Protein synthesis

85
Q

Cephalosporins affects what part of the bacteria?

A

Cell wall synthesis

86
Q

Nystatin affects what part of the bacteria?

A

Membrane function

87
Q

Sulfonamides affects what part of the bacteria?

A

Synthesis of essential metabolites

88
Q

Aminoglycosides affects what part of the bacteria?

A

Protein synthesis

89
Q

Rifampin affects what part of the bacteria?

A

DNA replication and transcription

90
Q

How can you control/ preset the build up of micro organism?

A 
Have good hygiene
Use mouthwash 
Fluoride
Get Immunised
Replacement therapy 
Use Probiotics 
Sterilisation 
Disinfection 
Pasteurisation
91
Q

Define sterilisation

A

complete removal or destruction of all viable organisms (using autoclave or an oven)

92
Q

How can antibitoics be classified?

A

By the part of the bacteria they target eg:

  1. Cell wall synthesis
  2. DNA replication
  3. Protein synthesis
  4. Membrane function
  5. Synthesis of essential metabolites

IOE Dentistry - Oral Microbiology (5 decks)

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