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Microbiology > Week 2: Classification of Microorganisms > Flashcards

Week 2: Classification of Microorganisms Flashcards

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1
Q

What is classification?

A

The action to group things into different categories

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2
Q

What are the properties of gram-positive and gram-negative cell membranes and cell walls?

A

Positive: single membrane and thick cell wall
Negative: double membrane and thin cell wall

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3
Q

Who invented taxonomy classification?

A

Carl Linnaeus

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4
Q

What are the 2 major ideas of classification?

A
  1. Scientific nomenclature: binomial naming – i.e., Genus species (e.g., Escherichia coli = E. coli)
  2. Natural classification: group species according to physical traits – aims to reveal “natural order” of life (microorganisms not included though)
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5
Q

What does the scientific nomenclature ‘Homo sapiens’ mean?

A

Wise man

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6
Q

What does the scientific nomenclature ‘Escherichia coli’ mean?

A 
Escherichia = after Theodor Escherich
Coli = colon
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7
Q

What does the scientific nomenclature ‘Saccharomyces cerevisiae’ mean?

A

Fungus (myces) uses sugar (saccharin) to make beer (cerevisiae)

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8
Q

What does the scientific nomenclature ‘Streptococcus pyogenes’ mean?

A

cocci (coccus) in chains (streptos) that cause pus formation (pyogenes)

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8
Q

What does the scientific nomenclature ‘Streptococcus pyogenes’ mean?

A

cocci (coccus) in chains (streptos) that cause pus formation (pyogenes)

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9
Q

What are the major changes in classification throughout history?

A

1735 Carl Linnaeus: Vegetabilia & Animalia

1866 Haeckel: Vegetabilia, Animalia & Protista

1925 Chatton: Prokaryota & Eukaryota

1938 Copeland: Monera, Protista, Plantae & Animalia

1969 Whittaker: Monera, Protista, Fungi, Plantae & Animalia

1977 Woese et al: Eubacteria, Archaebacteria, Protista, Fungi, Plantae & Animalia

1993 Cavalier-Smith: Eubacteria, Archaebacteria, Archezoa, Protozoa, Chromista, Fungi, Plantae & Animalia

2015 Ruggiero et al: Bacteria, Archaea, Protozoa, Chromista, Fungi, Plantae & Animalia

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10
Q

Who discovered the classification Chromista?

A

Cavalier-Smith 1981

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11
Q

What is Chromista?

A

Contain chlorophyll c
Don’t store their energy as starch
Photosynthetic chromists often carry various pigments that give them a brown or golden colour.

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12
Q

Why do we classify organisms?

A

To have a consistent nomenclature
To understand “natural order”
To identify and distinguish organisms according to their properties
For environmental biology

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13
Q

What bacteria causes ‘Whopping cough’ (100-day cough)?

A

Bordetella Pertussis (gram -ve coccobacilli)

NB: especially harmful to babies as it narrows airways when inflamed

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14
Q

Which species of Bordetella causes severe diseases in animals?

A

Bordetella bronchiseptica (gram -ve bacilli)

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15
Q

How does B. bronchiseptica work with other bacteria to cause disease in pigs?

A

B. bronchiseptica & Pasteurella multocida (gram -ve coccobacilli)

They act synergistically to cause atrophic rhinitis

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16
Q

What is Atrophic rhinitis?

A

Arrested growth and distortion of the turbinates in the nasal terminus (snout)

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17
Q

How does B. bronchiseptica cause disease in dogs?

A

Acute tracheobronchitis (Kennel cough) - typically a harsh, honking cough

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18
Q

How does B. bronchiseptica cause diseases in cats?

A 
Tracheobronchitis
Conjunctivitis
Rhinitis (upper respiratory tract infection - URI)
Mandibular lymphadenopathy
Pneumonia
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19
Q

What is a common example of a bacteria that causes watery diarrhoea?

A

Vibrio cholera (gram -ve spirillum)

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20
Q

What gram +ve coccus bacteria causes skin infection?

A

Staphylococcus aureus

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21
Q

why is it important that we identify & classify organisms that cause diseases?

A
  1. Accurate diagnosis – eg not all diarrhoea is caused by V. cholera
  2. Appropriate treatment – eg antibiotic for bacteria
  3. Develop vaccines for preventions
  4. Analysis of transmission – identify sources of infection
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22
Q

What are the disadvantages of using physical traits as an identification?

A

Doesn’t reveal relatedness/biology/phylogeny

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23
Q

What are the features used to classify bacteria?

A
  1. Shape (coccus/rods/spirochete…)
  2. Arrangement of cells (single/chain…)
  3. Cell wall (gram staining)
  4. Spore/non-spore forming
  5. Enzyme activity (catalase/oxidase…)
  6. Growth temp range
  7. Anaerobic/aerobic…
  8. Metabolism/biochemistry
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24
What is a phylogeny tree?
A branched diagram that infers the evolutionary relationship between biological species
25
Who developed the use of RNA gene sequencing to determine phylogeny in bacteria?
Carl Woese (1928-2012)
26
What are the rRNA small subunits in bacteria and eukaryotes?
16S in bacteria | 18S in eukaryotes
27
Why are SSU rRNA genes used in phylogeny?
1. Universal 2. Function is essential for survival (i.e., all need ribosomes) 3. Changes in DNA sequence level are acquired slowly
28
What did Woese discover in regard to bacteria?
A new group (Archaea) can be separated within bacteria
29
The more genetic difference in the rRNA sequence of species, the _?
less related the species are
30
What can you conclude about the closeness of the relationship between bacteria, archaea and eukaryotic rRNA sequences?
1. Archaea more like each other than Bacteria/Eukarya 2. Bacteria more like each other than Archaea/Eukarya 3. Eukaryotes more like each other than Archaea/Bacteria Thus, this can help construct a phylogeny tree
31
What does the final joining point in the SSU rRNA phylogeny tree show?
Relationships among different biological species are believed to have a common ancestor
32
What are Woese’s 8 taxonomic rankings?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
33
What are the possible effects of mutation?
1. Some don’t affect function – likely to accumulate rapidly | 2. Some affect function – slowly accumulate
34
What did Robert Hooke discover using a microscope?
Observed and reported that living things were composed of little boxes (cells)
35
Who is the pioneer of Cell theory?
Robert Hooke
36
Who is the father of microbiology?
Anton van Leeuwenhoek
37
What did Anton van Leeuwenhoek discover?
Found animalcules in rainwater, faeces and tooth scrapings under a microscope
38
What is spontaneous generation?
Where living organisms can be generated from a non-living object - ie 'vital force'
39
Who used maggots and meat to reject the idea of spontaneous generation?
Francesco Redi (1668)
40
How was Francesco's 1st experiment done?
2 glass jars with meat inside 1 control jar (sealed) - no maggots 1 open jar - maggots appeared
41
What did Francesco conclude from his 1st experiment?
Maggots don't spontaneously generate & only generate when flies lay their eggs on meat
42
What are further experiments that responded to critics that didn't believe in Francesco's hypothesis?
3 control (sealed completely) - no maggots 3 open jars - maggots appeared 3 jars sealed with fine net - flies hovered on top but no maggots
43
What did the further experiment of Francesco conclude?
Fine net allows fresh air in and thus attracted flies Maggots don't spontaneously generate & only generate when flies lay their eggs on meat
44
Who suggested that microbes from air entered Needham’s broth after boiling in 1765?
Lazzaro Spallanzani
45
Who defeated the idea of spontaneous generation?
Louis Pasteur (1861)
46
What were the procedures of Pasteur's experiment?
1. Non-sterile liquid poured into a flask 2. Neck of flask drawn out in flame 3. As liquid is sterilised by extensive heating, steam is forced out the open end 4. Liquid is then cooled slowly 5. As dust & microorganisms are trapped in bend, liquid remains sterile indefinitely 6. Flask was then tipped so microorganism-laden dust contacts sterile liquid 7. Microorganisms now grow in liquid
47
What did we learn from Pasteur's experiment?
1. Bacteria doesn't spontaneously generate 2. Bacteria are abundant in the environment and can easily contaminate materials 3. Basic sterile technique is used today to avoid contamination of bacterial cultures 4. Scientific progress always involves progressively ruling out other explanations 5. Always important to consider the evidence and challenge current understanding
48
How was Pasteur’s experiment not a clear cut in reality?
Some bacteria produce spores that are not killed just by boiling (endospores)
49
Before the mid-19th century, what were diseases known to be caused by?
Evil spirits | Miasmas - bad air - “malaria”
50
Who investigated childbed fever (puerperal fever) in obstetric clinics in the 1840s?
Ignaz Semmelweis
51
What had Semmelweis noticed from his investigations in childbed fever?
Noticed clinic teaching trainee doctors had a much higher infection and death rate than clinic teaching trainee midwives Observed death of a friend cut with a scalpel during the autopsy - realised that medical students who came to obstetric clinic from the autopsy room could be bringing infection with them
52
What had Semmelweis noticed from his investigations in childbed fever?
Noticed clinic teaching trainee doctors had a much higher infection and death rate than clinic teaching trainee midwives Observed death of a friend cut with a scalpel during the autopsy - realised that medical students who came to obstetric clinic from the autopsy room could be bringing infection with them
53
What did Semmelweis propose to reduce the infection rates?
Introduced strict handwashing - resulted in improved mortality rate
54
Why wasn't Semmelweis able to convince the medical establishment with his proposals?
His theory conflicted with medical opinion and he had no scientific explanation at the time He was seen as a maverick in his lifetime - committed to an asylum, where he died of blood-poisoning soon after
55
How did John Snow stop the outbreak of Cholera?
By removing the handle that contaminated the water in Soho from the pump - Birth of epidemiology
56
Who proposed the Germ theory of disease?
1860s Joseph Lister - "Father of Modern Surgery”
57
What did we learn from the Germ theory of disease?
Introduced antiseptic techniques for wounds and use of carbolic acid as disinfectants - to reduced rates of surgical infection and gangrene
58
What did Thomas & Breinl discover in mice?
1905 Atoxyl protected mice from trypanosomes (a protozoan infection) - though not effective in humans
59
Who modified Atoxyl to produce a better therapeutic index?
Ehrlich, Hata, Bertheim
60
What was the 1st effective antibacterial agent that killed spirochaete bacteria responsible for syphilis?
Salvarian
61
Who discovered the antibacterial activity of penicillin in 1928?
Alexander Fleming
62
Who was responsible for the start of the antibiotic revolution in 1940?
Florey, Chain & Heatley - purified penicillin for human use
63
Give examples of new class antibiotics discovered in the 1940s-1950s that targeted bacterial metabolic pathways.
1. Waksman and streptomycin from soil microbes | 2. Brotzu and cephalosporin from sewage microbes

Microbiology (3 decks)

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