Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICROBIO > GENERAL > Flashcards

GENERAL Flashcards

1
Q

Describe the 5 steps of Koch’s postulates

A
  1. The microorganism is present in every case of the disease but absent from healthy organism
  2. The suspected organism must be isolated and grown in a pure culture
  3. The same disease must result when the isolated microorganism is inoculated into a healthy host
  4. The same microorganism must be isolated again from the diseased host
  5. The antibody to the organism should be detected in the patient’s serum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does endogenous mean?

A

Associated with the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the term used to describe bacteria associated with the body

A

Endogenous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does exogenous mean?

A

Associated with the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the relationship between the bacteria and host if the host does not gain from the association with the bacteria, but is also unharmed, while the bacteria gains advantage?

A

Commensal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the relationship between the bacteria and host if they both gain mutual value? Explain how this happens

A

Mutualistic/Symbiotic.
Organism can produce nutrients or vitamins that can degrade harmful chemicals. Idea of colonisation resistance where endogenous microbial population confer protection against exogenous pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe a parasitic relationship between bacteria and host

A

Host is harmed but parasite gains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define pathogen

A

A microbe that is capable of causing host damage, includes classical pathogens and opportunistic pathogens, and damage produced directly or via the host immune response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define pathogenicity

A

Pathogenicity refers to the capacity to cause disease or damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define virulence

A

Virulence refers to the capacity of a microbe to cause damage to the host. It is related to an organism’s toxigenic potential and invasiveness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is LD50?

A

The lethal dose required to kill 50% of the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is ID50?

A

The infectious dose required to infect 50% of the hosts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define virulence factor

A

A component of a pathogen that enhances its pathogenicity, helping it to damage the host.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

List the 5 steps of molecular koch’s postulates

A
  • A virulence trait should be strongly associated with pathogenic strains of the species
  • Inactivation of the gene(s) associated with the virulence trait should decrease pathogenicity
  • Restoration of an inactivated/mutant gene with the wild type restores pathogenicity
  • The gene is expressed at some point during infection
  • Antibodies directed against the gene product protects the host
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

List 2 limitations of koch’s postulates.

A
  1. Organism cannot be cultured/isolated - obligate intracellular organisms
  2. Unethical to inoculate a human with the pathogen - no model organisms to inoculate since organism is a human pathogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an obligate pathogen?

A

Bacteria that must cause disease in order to be transmitted from one host to another. Bacteria must also infect a host in order to survive as it is incapable of surviving outside of host.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an opportunistic pathogen?

A

Bacteria that do not have to cause disease for transmission i.e. can be transmitted from one host to another without having to cause disease. However, in a host whose immune system is not functioning properly, the bacteria can cause an infection that leads to a disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are accidental pathogens?

A

Pathogens whose transmission are prevented or hindered by disease. They can be part of normal flora but not transmitted as a result of disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give an example of an obligate pathogen

A

Treponema Pallidum

Mycobacterium tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Give an example of an opportunistic pathogen

A

S. oralis
Actinomyces
S. anginosus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Give an example of an accidental pathogen

A

Bacteroides fragilis

Neisseria meningitides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Define plaque

A

A biofilm of bacteria that grows on surfaces within the mouth, such as the tooth surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

List 3 main components of dental plaque

A
  1. Living and dead bacteria
  2. Extra-cellular bacterial products
  3. Host compounds (from gingival crevicular fluid + saliva)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Define biofilm

A

Biofilm refers to an aggregation or community of bacteria that grows on surfaces, embedded within a self-produced extracellular matrix.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How many % of bacteria causing human infections exist as biofilm?

A

65%

26
Q

List 3 properties of a typical biofilm

A
  1. Spatially organized in a 3D structure
  2. Bacterial cells are enclosed in extra-cellular matrix
  3. Increases habitat range of individual bacteria - confers a selective advantage
27
Q

What is the major non-living component of plaque?

A

Extracellular Polymeric Substances (EPS) / Glycocalyx

28
Q

How many % of total plaque volume is the Extracellular Polymeric Substance?

A

30%

29
Q

What is the extracellular polymeric substance composed of?

A

Host products and bacterial products;

incorporates the gingival and proteins from the crevicular exudate.

30
Q

What is the pre-requisite for bacterial attachment to enamel?

A

Requires an acquired pellicle

31
Q

Define acquired pellicle

A

It is the layer of material acquired by a cleaned tooth

32
Q

What is the acquired pellicle made of? (x4)

A
  • mucins
  • salivary glycoproteins
  • minerals
  • immunoglobulins
33
Q

How long does the acquired pellicle take to form?

How long does it take to reach its max thickness?

A

form within seconds; 90-120 mins for max. thickness

34
Q

What is the function of the pellicle?

A

Bridges the adhesion of bacteria to enamel

35
Q

Which cell wall component contributes to charge and attachment?

A

Lipoteichoic acid

36
Q

Define amphipathic molecules

wrt lipoteichoic acid

A

Amphipathic molecules refer to those with one hydrophobic and one hydrophilic end. The hydrophobic (lipid) end is embedded in the membrane while the glycerol phosphate and hydrophilic end is at the outside

37
Q

How does the environment change on adhesion of bacteria to pellicle? (x3)

A
  1. Aerobic to anaerobic environment
  2. pH, nutrients, ions, metabolic products
  3. New attachment sites, co-aggregation
38
Q

Name 2 extracellular polysaccharide substances

A
  1. Glucans

2. Fructans

39
Q

What are glucans?

A

Glucose polysaccharides with glucose molecules joined by a(1,3) or a(1,6) links

40
Q

What are fructans?

A

Fructose polysaccharides with fructose molecules joined by B(2,6) or B(2,1) links

41
Q

What is the enzyme catalyzing the glucan reaction?

A

Glucosyltransferase

42
Q

State the glucan reaction

A

sucrose + (glucan)n –> (glucan)n+1 + fructose

43
Q

State the fructan reaction

A

sucrose + (fructan)n –> (fructan)n+1 + glucose

44
Q

What is the enzyme catalyzing the fructan reaction?

A

Fructosyltransferase

45
Q

What are adhesins?

A

Specific molecules on bacterial surface that recognise specific ligands or receptors on tooth surface

46
Q

What are lectins?

A

Sugar binding proteins that recognise carbohydrate groups and bind them

47
Q

Functions of fimbriae (x2)

A
  1. Adhesion to other bacteria

2. Adhesion to enamel/pellicle

48
Q

Which bacteria dominates at 24h?

A

Streptococcus (S. Oralis)

49
Q

List the steps of plaque development? (x6)

A
  1. Clean enamel surface
  2. Pellicle formation - 2s
  3. Pioneer bacteria - 1 min
  4. Micro-colonies & Extracellular polysaccharide - 2h
  5. Biofilm development - 2h onwards
  6. Mature plaque - 48h
50
Q

List the 3 types of adhesion seen in dental plaque

A
  1. Cell-substratum adhesion
  2. Homotypic cell-cell adhesion
  3. Heterotypic cell-cell adhesion
51
Q

Define homotypic cell-cell adhesion

A

Interaction of a specific cell with an identical cell

52
Q

Define heterotypic cell-cell adhesion

A

Adhesion between 2 different type of cells

53
Q

Give 2 examples of heterotypic cell-cell adhesion

A
  1. Actinomyces with Prevotella

2. S. Oralis with Prevotella

54
Q

What are synergistic interactions?

A

Enzymes secreted / released upon lysis benefits more than 1 species

55
Q

What is homofermentation of glucose?

A

Conversion of 1 molecule of glucose into 1 fermentation product, which is 2 moles of lactic acid

56
Q

What does heterofermentation of glucose refer to?

A

Conversion of 1 molecule of glucose into more than 1 fermentation product, namely 1 mole of lactic acid, 1 mole of ethanol and 1 mole of CO2

57
Q

What does protein breakdown in plaque produce? What is the effect?

A

Production of ammonia gas (NH3) –> Counters the development of low pH for cariogenic activity

58
Q

What are antagonistic interactions?

A

Competition of substrates between micro-organisms, which can result in the production of bacteriocins to damage competitors

59
Q

Define bacteriocins

A

A substance, usually a protein, released by one bacteria that kills another, usually by inducing a metabolic block.

60
Q

Name the bacteriocin produced by streptococcus and state their function

A

Mutacins;
Peptide antibiotics produced by S. Mutans that specifically inhibits the growth of closely related species, that would otherwise compete for the same nutrients.

61
Q

Name 10 components of the enamel/salivary pellicle

A
  1. Mucins
  2. Acidic Proline-Rich Proteins (PRPs)
  3. Statherin
  4. Amylase
  5. Lysozyme
  6. Albumin
  7. Immunoglobulins
  8. Glucosyltransferases
  9. Glucans
  10. eDNA
62
Q

Name 4 reasons for variation found in dental plaque

A
  1. Sites of plaque (supragingival; mainly aerobic gram-positive VS subgingival; mainly anaerobic gram-negative)
  2. Time (rapid vs slow build up, and time since last meal)
  3. Genetics; Saliva and GCF composition varies from individual to individual
  4. Diet (e.g. low carb vs high carbs; low protein vs high protein etc.)

MICROBIO (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions