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Foundations of Biomedical Science (see class description for full access) > Introduction to Microbiology, Microbiological Concepts & Biochemistry of Microbes > Flashcards

Introduction to Microbiology, Microbiological Concepts & Biochemistry of Microbes Flashcards

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1
Q

Which doctor first used handwashing to reduce clinical infection?

A

Ignaz Semmelweis

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2
Q

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

A

Joseph Lister

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3
Q

What is abiogenesis and who disproved that this is how infections start?

A

Abiogenesis is the theory of spontaneous generation. Louis Pasteur was able to disprove this

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4
Q

Which scientist first demonstrated that microorganisms caused infectious disease? What two diseases did this person study in the process?

A

Robert Koch demonstrated that microorganisms caused infectious disease through his Germ Theory of Disease (Koch’s Postulates). In the process, he studied anthrax and tuberculosis

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5
Q

What is a pure culture?

A

A population of a certain type of cells that are cultured and grow separately from any other type of cell

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6
Q

List Koch’s Postulates

A
  1. The specific causative agent must be found in every case of an infectious disease
  2. This agent is taken and cultured purely
  3. A sample is inoculated and transferred to a healthy, susceptible animal. This must cause the same infection.
  4. The microbe is extracted from the infected animal
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7
Q

Three domains of life

A
  • Eubacteria
  • Archea
  • Eucarya
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8
Q

Principle members in eubacteria

A
  • Gram positive bacteria

- Gram negative bacteria

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9
Q

Principle members in eucarya

A
  • Protozoa
  • Algae
  • Fungi
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10
Q

What is the main difference between eukaryotic and prokaryotic cells

A

Eukaryotic cells have a nucleus, prokaryotic cells have no nucleus

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11
Q

Key features of algae

A
  • Eukaryotic
  • Photosynthetic
  • Unicellular or multicellular
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12
Q

Three motility mechanisms for protozoa

A
  • Cilia
  • Flagella
  • Psuedopodia
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13
Q

Are fungi eukaryotic or prokaryotic?

A

Eukaryotic

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14
Q

How do fungi differ from plants and animals?

A
  • Differ from plants as they do not use photosynthesis for energy
  • Differ from animals as they have a cell wall
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15
Q

Name the two different types of fungi and how they differ to each other

A

Moulds: multicellular, reproduce through spores (sexually and asexually)
Yeasts: unicellular, reproduce by budding (asexually)

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16
Q

The cell wall of bacteria contains polysaccharide and peptidoglycan, true or false?

A

True

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17
Q

Name the two structures that make up all viruses

A
  • Nucleic acid (DNA/RNA)

- A protein coat (capsid)

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18
Q

Viruses that infect bacteria

A

Bacteriophages

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19
Q

Harmless microorganisms

A
  • Around 87% of microorganisms are harmless
  • These organisms are helpful and have an important role in the food chain
  • e.g. decomposition, nitrogen fixation
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20
Q

Opportunistic microorganisms

A
  • 10% of microoganisms are opportunistic
  • Microbes that are usually harmless but can be pathogenic when placed in different conditions
  • e.g. bowel flora that find their way to the bladder
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21
Q

Harmful microogranisms

A
  • Around 3% of microogranisms are overly harmful
  • Can cause disease when present in the body and upon initial contact with a healthy person
  • e.g. tapeworm, syphilis
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22
Q

Normal flora

A
  • Microbes that naturally inhabit surfaces of the human body
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23
Q

How can there be a greater microbial load in the body comparing to the number of cells in the body?

A
  • Total microbe load >10^3
  • Total cells in the body is 10^3
  • This is possible as microbes are much smaller than body cells
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24
Q

Eukaryotes

A
  • Fungi, algae and plants (simple cell wall)
  • Protozoa and animals (no cell wall)
  • Nucleus and nuclear membrane
  • Larger ribosomes
  • Larger than prokaryotes (10 - 100 micrometres)
  • Reproduce by mitosis/meiosis
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25
Q

Prokaryotes

A
  • Archaea and bacteria
  • Smaller than eukaryotes (0.1 - 10 micrometres)
  • No nuclear membrane or nucleus
  • Complex cell wall (with peptidoglycan for bacteria/eubacteria)
  • Smaller ribosomes
  • Reproduce by binary fission
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26
Q

Louis Pasteur

A
  • Disproved theory of spontaneous generation (abiogenesis)

- Discovered pasteurisation (originally used to prevent spoilage of wine)

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27
Q

Robert Koch

A
  • First to study anthrax and tuberculosis
  • Koch’s postulates
  • Contributed to develop staining methods for microbes
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28
Q

Robert Hooke

A
  • First person to describe a cell
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29
Q

Joseph Lister

A
  • Credited with developing antisepsis for surgery
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30
Q

Antoni van Leeuwenhoek

A
  • First to describe bacteria including their shapes
  • Reported existence of protozoa two years before
  • Bacteria took longer to discover as work was still being done on his microscope, and bacteria are a lot smaller than protozoa
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31
Q

Ignaz Semmelweis

A
  • First to use handwashing in clinical practice
32
Q

Bacteria

A
  • Do not have a nuclei
  • e.g. Escherichia coli
  • Prokaryotic
33
Q

Algae

A
  • Eukaryotes
  • Photosynthetic
  • Can be unicellular or multicellular
34
Q

Protozoa

A
  • Single celled eukaryotes
35
Q

Fungi

A
  • Have a cell wall
  • Not photosynthetic
  • Two types: moulds and yeasts

Moulds: multicellular, reproduce sexually and asexually (spores)

Yeasts: unicellular, reproduce asexually (budding)

36
Q

Viruses

A
  • Can only be seen with an electron microscope

- Cannot reproduce independently, must reproduce inside a host cell

37
Q

Bacteria cell wall composition (gram positive)

A
  • Thick layer of peptidoglycan

- Teichoic acid and lipoteichoic acid

38
Q

Bacteria cell wall composition (gram negative)

A
  • Thin layer of peptidoglycan

- Outer membrane contains lipopolysaccharide

39
Q

Glycocalyx

A
  • A gelatinous material which coats the surface of some bacteria
  • Capsules and slime
40
Q

Capsules

A
  • Highly organised
  • Well attached
  • Protect against phagocytosis
  • e.g. H. influenzae B
41
Q

Slime

A
  • Not highly organised
  • Not well attached
  • Helps bacteria to slide on surfaces
  • Protect bacteria from drying
  • Can be washed off easily
42
Q

Flagella, fimbriae and pili

A
  • Flagella: motility
  • Fimbriae: adherence
  • Pili: adherence and conjugation (passing DNA from one organism to another)
43
Q

Difference between gram positive and gram negative bacteria

A
  • Differences in the structure of their cell wall
44
Q

Steps of a gram stain

A
  • Spread bacteria across a slide with water
  • Heat fix the slide
  • Stain with crystal violet (30 sec)
  • Stain with iodine (30 sec)
  • Discolour with alcohol
  • Stain with carbol fuschin (30 sec)
45
Q

How bacteria grow

A
  • Binary fission
  • Single cell splits into two identical daughter cells
  • Chromosome duplicates, same genetic material in both cells
46
Q

Stages of bacterial growth in broth solution

A
  • Lag phase
  • Exponential phase
  • Stationary phase
  • Death/decline phase
47
Q

Obligate anearobe

A
  • An atmospheric condition

- Where bacteria is unable to grow in O2 and will only grow in the complete abscence of O2

48
Q

Facultative anearobe

A
  • Atmospheric condition where bacteria is able to grow with or without O2
49
Q

Carboxyphile

A
  • Atmospheric condition where bacteria grows best with an increased concentration of CO2
50
Q

Mesophile

A
  • An organism which grows best in moderate temperatures (optimum 37 degrees)
51
Q

Psychrophile

A
  • An organism which grows best in cold temperatures (optimum 15 degrees)
52
Q

Glycolosis

A
  • Occurs in all cells
  • Anaerobic process (no oxygen required)
  • Consists of 10 reactions
  • For every molecule of glucose, there is a net gain of 2 ATP and 2 molecules of pyruvic acid produced
53
Q

Respiration

A
  • Obligate aerobes and facultative microbes (oxygen required)

Krebs Cycle

  • Consists of 8 reactions
  • Utilises pyruvic acid
  • 2 ATP molecules produced
  • CO2 produced

Electron Transport Chain

  • Many redox reactions
  • Many ATP molecules produced
  • H2O produced
54
Q

Fermentation

A
  • Obligate anaerobes and facultative microbes (no oxygen)
  • Utilises pyruvic acid
  • Not as much ATP produced
  • Organic wastes (acids and alcohols) produced
55
Q

Catabolism

A
  • Larger molecules broken down into smaller molecules
56
Q

Anabolism

A
  • Smaller molecules built up into larger molecules
57
Q

Oxidation

A
  • Loss of electrons
58
Q

Reduction

A
  • Gain of electrons
59
Q

What factors (growth & nutritional conditions) need to be considered when culturing bacteria?

A
  • Temperature preferences (whether they grow best in cold temperatures or warm temperatures)
  • Atmospheric conditions (whether they can grow with oxygen, without oxygen, with more CO2 etc.)
  • Moisture
  • pH
  • Osmolarity
  • Nutrients
60
Q

Microbial biofilm

A
  • Composed of a complex mixture of microbes, cell debris and extracellular matrix
  • Found on natural, wet surfaces
  • Matrix is made of an extracellular slime layer
61
Q

How plaque leads to tooth decay

A
  • Sucrose in the diet is degraded by bacteria to produce acids
  • Build up of plaque&raquo_space; higher numbers of bacteria&raquo_space; greater production of acids&raquo_space; more demineralisation in teeth
62
Q

Virulence factor

A
  • Traits that give a microbe the ability to cause disease
  • Endotoxins and exotoxins
  • Production and release of enzymes
  • Production of hameolysins
  • Production of adherence factors (fimbriae, pili, glycocalyx)
63
Q

Difference between endotoxin and extotoxin

A
  • Endotoxins come from gram negative bacteria
  • Exotoxins come from gram positive bcteria
  • Endotoxins are within the cell wall
  • Exotoxins are inside the cell
  • Endotoxins are released when the cell dies and the cell wall breaks up
  • Exotoxins are released and secreted by the living cell
64
Q

Three types of haemolysis

A
  • Alpha: partial lysis around colonies (green/grey colour)
  • Beta: complete lysis
  • Gamma: no haemolysis
65
Q

Functions of parts of a light microscope

A
  • Condenser: focuses light through the specimen
  • Diaphragm: controls the amount of light going through the condenser
  • total magnification = objective size x occular size
66
Q

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

A
  • For unstained specimens, contrast can be increased by closing the condenser diaphragm
67
Q

Selective and differential media

A
  • Selective media only allow certain bacteria to grow while inhibiting others
  • Differential media contain substances that will allow different bacteria to be distinguished
    from each other
68
Q

Four principle shapes of bacteria

A
  • Bacillus (rods)
  • Coccus (round)
  • Spirals
  • Vibrio (comma shaped)
69
Q

Four principle types of microscopic arrangement

A
  • Diplococcus (pairs)
  • Chains
  • Clusters
  • Single cells
70
Q

Apart from colony morphology and the Gram stain, what other methods could be used to identify an
unknown organism?

A
  • Serotyping & detection of virulence factors (e.g. demonstration of specific enzymes)
  • Using molecular techniques
  • Observing biochemical characteristics
71
Q

What is the difference between the incubation period of a disease and the invasive phase?

A

Incubation:

  • No symptoms
  • The initial invading microbes invade body
  • They must overcome the host’s defences (e.g. skin, immune system)

Invasive:
- Identifiable disease with dramatic increase in microbes (may continue to
death)

72
Q

Microaerophile

A
  • A microorganism that requires oxygen to survive, but these levels must be lower than what is present in the atmosphere
73
Q

Mutualism

A
  • Symbiotic relationship where both members benefit
74
Q

Commensalism

A
  • Symbiotic relationship where one member

benefits without affecting the other

75
Q

Parasitism

A
  • Relationship where
    one member benefits while the other is harmed
  • also called amensalism or antagonism

Foundations of Biomedical Science (see class description for full access) (9 decks)

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