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MEDI1000 > Introduction to Microbiology P1&2 > Flashcards

Introduction to Microbiology P1&2 Flashcards

1
Q

In scientific nomenclature which part is the genus and which is the species - Staphylococcus aureus

A

Genus: Staphylococcus
Species: aureus

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2
Q

When writing or typing latin names of biological organisms, how must both component names be presented?

A

Italicised or underlined

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3
Q

Approximately what percentage of microbes are pathogenic?

A

3%

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4
Q

Approximately what percentage of microbes are harmless?

A

87%

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5
Q

Name 3 beneficial uses microbes in our society

A

Yeast: Bread
Fungi: Cheese, antibiotics
Bacteria: yogurt, antibiotics

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6
Q

Which scientist first described the cell?

A

Robert Hooke

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7
Q

Which scientist first described bacteria and their shape?

A

Antoni van Leeuwenhoek

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8
Q

Which doctor first used handwashing to reduce clinical infection?

A

Ignaz Semmelweis

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9
Q

in 1870 which doctor was the first to use antisepsis for surgery?

A

Joseph Lister

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10
Q

What is abiogenesis and who disproved that this was how infections started

A

Abiogenesis: Theory of spontaneous generation

Louis Pasteur

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11
Q

Which scientist discovered pasteurisation? What was it first used for?

A

Louis Pasteur

Originally to prevent spoilage of wine

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12
Q

Which scientist first demonstrated that micro-organisms caused infectious diseases? What were the 2 diseases studied?

A

Robert Koch
1- Anthrax
2- Tuberculosis

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13
Q

What is a pure culture?

A

Population of certain type of cells cultured and grown separately from any other type of cell

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14
Q

List Koch’s postulates

A

1- Specific causative agent must be found in every case of infectious diseases
2- Disease organism isolated in pure culture
3- Inoculation of sample of culture into healthy + susceptible animal. Animal must produce the disease
4- Diseased organism must be recovered from infected animal

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15
Q

What are the limitations to Koch’s postulates

A
  • Works with many bacteria
  • Does not work with viruses
  • Does not work with human only pathogens
  • Does not apply to non-infectious diseases
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16
Q

List the 3 domains of life

A

1- Bacteria
2- Archaea
3- Eucarya

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17
Q

What are the principle members for each domain of life?

A

1- Bacteria: Gram negative + positive
2- Archaea: halophiles, thermophiles. methanogens
3- Eucarya: Protozoa, fungi, algae

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18
Q

What is the main difference between eukaryotic and prokaryotic cells?

A

Eukaryotic: Contain nuclei
Prokaryotic: No nuclei

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19
Q

What are the key features of algae?

A
  • Eukaryotic
  • Contain chlorophyll; obtain energy from photosynthesis
  • multicellular and unicellular
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20
Q

List the 3 mechanisms of motility for protozoa

A

1- Cilia
2- Fimbriae
3- Pseudopodia

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21
Q

Fungi are prokaryotic (T or F)

A

False

Fungi have nuclei

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22
Q

How do fungi differ from plants and animals

A

Plants: No chlorophyll; cannot photosynthesise for energy
Animal: Has cell wall

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23
Q

Name two types of fungi

A

Moulds

Yeast

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24
Q

How do moulds and yeast differ to each other?

A

Moulds: Multicellular, reproduce asexually and sexually (spores)
Yeast: Unicellular, reproduce asexually (budding)

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25
Q

What is the name of the process of yeast reproduction?

A

Budding

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26
Q

The cell wall of bacteria contain polysaccharide and peptidoglycan (T or F)

A

True

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27
Q

Name the two structures that make up all viruses

A
  • Nucleic acid (DNA or RNA) - Capsid (protein coat)
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28
Q

What is the name of specialised group of viruses that infect bacterial cells?

A

Bacteriophage

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29
Q

What is the glycocalyx?

A
  • Gelatinous material, coats surface of some bacteria

- Made up of polypeptides and/or polysaccharides

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30
Q

Describe the two types of glycocalyx

A 
1- Capsule 
- Highly organised 
- Firmly attached 
- Protect against phagocytosis 
- Some typed by capsule composition 
2- Slime 
- Not highly organised 
- Not firmly attached 
- Helps bacteria to slide onto surfaced
- Protect from drying
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31
Q

Describe the function of flagella

A

Motility

32
Q

Describe the function of pili and fimbriae

A

Fimbriae: Adherence
Pili: Adherence and conjugation (Passing DNA from one organism to another)

33
Q

What is the main difference between gram positive and gram negative?

A

Gram positive: Stains purple, thick layer of peptidoglycan, teichoic acid, lipoteichoic acid
Gram negative: Stains pink, thin layer of peptidoglycan. lipopolysaccharide present in outer membrane

34
Q

List the steps of gram stain

A 
1- Heat fix smear 
2- Crystal violet 
3- Iodine 
4- Alcohol 
5- Carbol Fuchsia
35
Q

How do bacteria reproduce?

A

Asexually; binary fission
Single cell -> two identical daughter cells
Chromosome duplicates; same genetic material in both cells

36
Q

List the 4 growth phases in a broth culture

A

1- Lag phase
2- Exponential Phase
3- Stationary phase
4- Death/decline phase

37
Q

What are mesophiles, psychrophiles, obligate anaerobes, facultative anaerobes and Carboxyphiles?

A

Examples of ideal conditions for bacterial growth

38
Q

What are mesophile and psychrophiles?

A

Ideal temperature conditions
Mesophile: 10-45 degrees. Optimum: 37 degrees
Psychrophiles: 0 - <20 degrees. Optimum: 15 or lower

39
Q

What are:
Obligate anaerobes
Facultative anaerobes Carboxyphiles

A

Atmospheric conditions
1- Growth in complete absence of O2
2- Grow with/without O2
3- Grow in increased concentrations of CO2

40
Q

Describe bacterial respiration

A
  • Obligate aerobes and facultative microbes
  • Oxygen required
Krebs Cycle
- Uses pyruvic acid 
- 2 ATP produced
- CO2 produced 
Electron Transport Chain 
- Redox reactions 
- Many ATP produced 
- H2O produced
  • Overall produces ATP, CO2, H2O
41
Q

Describe bacterial fermentation

A
  • Obligate anaerobes and facultative microbes
  • Absence of oxygen
  • Uses pyruvic acid
  • Low ATP yield
  • Produces organic wastes; alcohol and acids
42
Q 
Describe glycolysis:
1- Starting carbohydrate 
2- Storage molecule
3- End product
4- Net energy molecules produced
A 
- Anaerobic; no oxygen 
1- Glucose C6H12O6
2- ATP
3- 2 pyruvic acid molecule
4- 2 ATP (4 produced, 2 used)
43
Q

Differentiate between catabolism and anabolism

A

Catabolism: Breakdown of chemical bonds
Larger molecules -> smaller molecules
Anabolism: Formation of chemical bonds
Smaller molecules -> larger molecules

44
Q

Differentiate between oxidation and reduction

A

Oxidation: Loss of electrons
Reduction: Gain of electrons

45
Q

What are the enzymes that are spreading factors? What is the role of enzymes in this regard?

A 
Enzyme breakdown health connective tissue 
- Kill host cells 
- Evade immune system 
1- Collagenase
2- Hyaluronidase
46
Q

What factors are considered when culturing bacteria?

A 
Temperature 
Atmospheric conditions
Moisture 
Ph
Osomolarity (salt)
Nutrientsa
47
Q

What is a microbial biofilm?

A

Found on wet surfaces
Composed of microbes, cell debris and extracellular matrix
Matrix composed of e.c slime layer

48
Q

How does plaque leads to tooth decay?

A

Sucrose in diet degraded by bacteria producing acids

Increased bacteria = acid production = demineralisation

49
Q

What is a virulence factor? Give examples.

A

Traits that give microbe ability to cause disease
1 - Toxins; endotoxins and exotoxins
2- Adherence factors; fimbriae, pili, glycocalyx
3- Enzymes: production and secretion
4- Production haemolysins

50
Q

What is the difference between exotoxin and endotoxin?

A

Exotoxin:
- Gram positive
- Secreted by living cell (cell does not have to die before toxin is secreted)
- Passes through cell wall, secreted into extracellular
Endotoxin:
- Gram negative
-Toxic compound: lipopolysaccharide (embedded in cell call)
- Toxin released when cell dies

51
Q

What are the three types of haemolysis on a blood agar plate?

A

Rupture of red blood cells
1- Beta: Complete lysis
2- Alpha: Partial lysis
3- Gamma: No haemolysis

52
Q

Describe the function of condenser lens, iris diaphragm

A

1- Focusses light through specimen

2- Controls amount of light entering condenser

53
Q

How is total magnification calculated?

A

Objective size x ocular size

54
Q

How would you increase the contrast looking at an unstained preparation with bright field illumination?

A

Closing condenser diaphragm = increased contrast

55
Q

What is the difference of a mixed and pure culture? How can you tell a difference?

A

Mixed: More than one colony type present
Pure: one type of colony type present
Identify any different shapes, colours, size

56
Q

Explain selective and differential media

A

Selective: Allow certain bacterial growth, inhibiting others
Differential: Contains substances to allow different bacteria to be distinguished

57
Q

Four principle shapes of bacteria

A

Bacilli (rod)
Cocci (round)
Spirals
Vibrio (comma)

58
Q

Four types of arrangement

A

Diplococcus (pairs)
Chains
Clusters
Single

59
Q

What are other methods to identify an unknown organism?

A

Serotyping
Detection of virulence factors
Molecular techniques
Observe biochemical characteristics

60
Q

Difference between incubation period and invasive period

A 
Incubation:
- No symptoms 
- Initial invading microbes invade body 
- Must overcome host defences 
Invasive:
- Disease is identifiable
- Increase in microbes
61
Q

What is a microaerophile?

A

Microorganism that requires oxygen to survive

Levels must be lower than present atmosphere

62
Q

Which parts of the body are considered sterile?

A

Blood
Tissues
Lower respiratory tract

63
Q

What is an opportunist pathogen?

Give an example

A

Normally considered harmless
Become pathogenic when place in different conditions
Bowel flora that enter bladder

64
Q

Define Mutualism

A

Symbiotic relationship

Both members benefit

65
Q

Commensalism

A

Symbiotic relationship
One member benefits
Other not harmed

66
Q

Parasitism

A

One member benefits
Other is harmed
Amensalism or antagonism

67
Q

Describe the characteristics of Eukaryotes

A
  • Simple cell wall: Fungi, algae and plants
  • No cell wall: Protozoa, animals
  • Nuclear membrane
  • Nucleus
  • Larger ribosomes
  • Larger than prokaryotes
  • Reproduce by mitosis/meiosis
68
Q

Describe the characteristics of Prokaryotes

A
  • Archaea and bacteria
  • Smaller than eukaryotes (0.1 - 10 micrometres)
  • No nuclear membrane
  • No nucleus
  • Complex cell wall (with peptidoglycan for bacteria/eubacteria)
  • Smaller ribosomes
  • Reproduce by binary fission
69
Q

Why did it take Leeuwenhoek longer to discover bacteria (after protozoa)?

A

Bacteria much smaller than protozoa

Microscope not advanced to detect presence of bacteria

70
Q

What is the role of glycocalyces with bacteria?

A

virulence; bacteria often become more pathogenic

Adherence, protection from phagocytosis, some protection from antibiotics

71
Q

Define sporulation

A

Bacteria can make a copy of their DNA with some cytoplasm and enclose it in thick layers of protein

72
Q

What are the two spore forming genera of bacteria??

A

Bacillus

Clostridium

73
Q

What are acidophiles, alkalophiles and neutrophiles?

A

Examples of ideal pH conditions for bacterial growth

74
Q

What are the stages of infectious diseases? What happens at each stage?

A

Incubation: No symptoms, invading microbes colonise body site
Prodromal: Mild symptoms
invasive: Identifiable disease with increase in microbes
Decline: Decline in microbes
Convalescence: Recovery

75
Q

How do enzymes cause the rapid spread of infection?

A

1- Invasive bacteria reach epithelial surface
2- Bacteria produce hylauronidase + collagenase
3- Bacteria invade deeper tissues

MEDI1000 (2 decks)

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