Classification of Microorganisms Flashcards Preview

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Flashcards in Classification of Microorganisms Deck (38):
1

What is taxonomy?

The science of classifying organisms

2

Two advantages of taxonomy?

Provides universal names for organisms and provides a reference for identifying organisms

3

Who is the 'father of taxonomy'?

Carl Linnaeus

4

What two major ideas did Carl Linnaeus come up with?

Scientific nomenclature and natural classification

5

What is scientific nomenclature?

The naming of organisms, 1st part is the genus and the second part is the species name

6

What is phylogeny?

The study of the evolutionary history of organisms

7

What is hierarchy?

A hierarchy is an organizational structure in which items are ranked according to levels of importance.

8

What is a taxon?

A group of one or more populations of an organism or organisms seen by taxonomists to form a unit.

9

The hierarchy of taxa reflects...

Phylogenetic relationships

10

What is natural classification?

The theory of grouping species according to shared physical traits

11

What did Linnaeus propose as the Kingdoms?

Animalia, Vegetabilia and Minerals

12

What was the main downfall of natural classification proposed by Linnaeus?

Bacteria and archaea not considered by Linnaeus

13

Where did Nageli propose that bacteria should be placed?

In the plant kingdom - led to the term microflora

14

Who introduced the Protista kingdom?

Haeckel - grouped bacteria, protozoa, fungi and algae in to protista

15

Chatton came up with two kingdoms, prokaryota and eukaryota in 1937, why?

He used electron microscopy and distinguished between nucleated and non-nucleated cells

16

Before Carl Woese, what was used to classify bacteria?

Physical traits such as shape, number of cells, gram staining, growth temperature range, etc.

17

What did Carl Woese propose?

Five kingdoms, Bacteira, Archaebacteria, Protista, Fungi, Plantae and Animalia originally. Then elevated Domains above kingdoms

18

Who came up with the three domains and what are they?

Carl Woese - Eukaryotes, Archaea and Bacteria

19

What does Woese's classification emphasise?

The difference between bacteria and archaea

20

How did Woese come to separate bacteria and archaea?

Based on the observation that ribosomes are not the same in all cells

21

What did Woese do differently in classification?

He based the split on genetic rather than morphological traits

22

What did Woese analyse?

Small subunit ribosomal RNA from various organisms 16S for prokaryotes and 18S for eukaryotes

23

What does SSU rRNA stand for?

Small subunit ribosomal RNA

24

What does SSU rRNA encode?

Encode for RNA molecules used in translation of nucleic acid

25

SSU rRNA can be used because it is present in...

All cells

26

What is special about SSU rRNA?

Allows you to compare all living organisms with each other

27

Why is SSU rRNA essential for life?

If you lose the ability to synthesise proteins, the organism dies

28

Explain what the yellow region in the diagram shows

Q image thumb

Highlighted in yellow are the sequences that are conserved throughout history - no mutations in these regions, so yellow regions must have to do with the function of SSU rRNA

29

Explain what the blue regions show 

Q image thumb

Differences in the SSU rRNA code, direct comparisons can be made between different organisms. 

30

How does SSU rRNA serve as a molecular clock?

Measures the evolutionary relatedness of sequences

31

The more genetic differences between two sequences...

The less related they are 

32

Why do sequences for housekeeping genes make good molecular clocks?

Found in all/most organisms and they are under functional pressure to aquire few mutations

33

What is the function of the diagram?

Q image thumb

Provide quantitative data to construct a phylogenetic tree

34

What do phylogenetic trees show?

Phylogenetic trees show evolutionary relationships among different biological species that are believed to have a common ancestor

35

Woese's work lead to eight taxonomic rankings, they are...

Domain, kingdom, phylum, class, order, family, genus, species (King Philip came over for great spaghetti)

36

Two problems with single gene analysis (e.g. SSU rRNA)?

1. Lack of divergence between two very closely related sequences can limit effectiveness at distinguishing two organisms. 

2. Fails to account for lateral gene transfer

37

How to overcome the two issues bought about by single gene analysis?

Multi-gene or entire genome comparisons could be made 

38

Medical importance of phylogenetics?

Pathogenic bacteria isolated from the patient. Compare characteristics to traits from previously classified bacteria. Guides treatment.