week 10 - classification

Question 1

characteristics used in classification

Answer 1

morphological

physiological

clinical diagnostics

Question 2

characteristics used in classification
- morphological

Answer 2

Macroscopic
* Colony morphology

Microscopic
* Size, shape, Gram stain motility, ultrastructure, endospore

Question 3

characteristics used in classification
- physiological and metabolic

Answer 3

Directly related to activity of e.g. enzymes

Indirectly related to genes

Question 4

characteristics used in classification
clinical diagnosis: the API strip

Answer 4

Cupules contain dried reagents
Inoculated with bacterial suspension
Colour changes indicate metabolic properties
Profile used to give identification

Question 5

why not use fossils

Answer 5

poor fossil record

so not very helpful

Question 6

molecular approaches

Answer 6

• Bacteria are all related by descent
• Sequence of the genome if a “record” of the bacterium’s ancestry
• 16S rRNA gene
• Present in all the organisms to be compared
• Has the same function
• The function of 16S rRNA is essential
• Conserved
• Has stable regions
• Has variable regions
• DNA sequencing covered in 2nd year

Question 7

universal evolutionary tree based on…

Answer 7

rRNA sequence comparison

3 domain
- eubacteria
- archaea
- eukaryotes

Question 8

what did rRNA sequencing tell us?

Answer 8

This sequencing told us that archaea had a more recent ancestry with euks than bacteria