Evolution and systematics

Question 1

Origin of life?

Answer 1

1. Biological building blocks Amino acids, Nucleoside, Sugar
2. “RNA-world” Catalytic RNA, Self-replicating RNA
3. Protein synthesis More efficient catalysts (proteins) evolved
4. “DNA-world” RNA → DNA
5. Lipid bilayers Lipid vesicles as membranes?

Question 2

Oxidation of the Earth?

Answer 2

Cyanobacteria (oxygenic phototrophs)
• Evolved 2.8 billion years ago
• Oxygen → Iron-oxides, i.e. atmosphere was not altered

Great oxidation event
• Happened 2.4 billion years ago
• Anoxic to oxic atmosphere
o O2 accumulation in atmosphere (required by aerobic organisms)
o O3 accumulation
(protection against UV)
Aerobic/anaerobic organisms could start evolving

Question 3

Microbial species?

Answer 3

Morphological properties
• Physiological properties
• Biochemical properties
• 16s rRNA sequencing
• Molecular methods

Question 4

Morphology?

Answer 4

The shape of cells/colonies?
The size of cells/colonies?
The look of cells/colonies?
Gram-reaction?
Do the bacteria form spores?
Is the bacterium motile? How? (flagella, gliding or through gas vesicles)
Arrangement of flagella? (if there are any)

Question 5

Nutrition and physiology?

Answer 5

Extraction of energy? (phototroph, chemoorganotroph, chemolithotroph)
How does the bacteria like, temperature, pH and salt?
What carbon-, nitrogen-, and sulphur-sources can the bacteria use?
What is required for bacterial growth?

Question 6

Other properties?

Answer 6

Pigmentation?
Antigenic properties (serological)
Pathogenicity (disease-causing ability)
Susceptibility against antibiotics?