The microbial world and the tree of life

Question 1

What is a stromatolite

Answer 1

Layered sedimentary formations created mainly by photosynthetic microorganisms such as Cyanobacteria

Question 2

What is the fossil evidence of early bacterial life?

Answer 2

Stromatolites in carbonate sediments (made of Cyanobacteria or blue green algae)

Question 3

When is the oldest stromatolite from?

Answer 3

Archaean (2nd of 4 geologic Eons - Hadean, archean, Proterozoic, Phanerozoic)

Question 4

4 impacts of microorganisms on human society

Answer 4

1) microbes and disease (improve understanding of disease, sanitation, public health)
2) microbes and agriculture (leguminous plants and nitrogen fixation, human intestinal tract, microbes inhabiting rumen of cattle and sheep)
3) microbes and food (spoilage and fermentation to make cheese, yoghurt, beer)
4) microbes and industry (microbes when growing as a biofilm can cause problems eg. Blockages or spoilage. But when brown in large quantities can also be beneficial in producing antibiotics, enzymes and chemicals.)

Question 5

Classification of the five kingdom is still …

Answer 5

Ambiguous (for example are there five or six kingdoms? Is archaea a separate kingdom?)

Question 6

What can happen between the five kingdoms ?

Answer 6

Can exchange genetic material

Question 7

Timeline of seeing microorganisms (3 points)

XXX may need to fill in extra points later dk if it’s in prelims

Answer 7

700BCE: The Assyrians made a ‘Nimrud lens’ - rock crystal disk with convex shape

1660: Robert Hooke published Micrographia (descriptions of every he saw with his magnifying glass)
2009: ETEM (environmental transmission electron microscope)

Question 8

Monera

Answer 8

Biological kingdom made up of prokaryotes (particularly bacteria)

Question 9

Linnaeus

Answer 9

2 kingdoms plant and animal

1735

Question 10

Haeckel

Answer 10

3 kingdoms Protista, plant and animal

1866

Question 11

Chaton

Answer 11

2 empires
Prokaryote and eukaryote (coined these terms)
1937

Question 12

Copeland 1956

Answer 12

4 kingdoms
Monera, protoctista, plant, animal

(He moves bacteria and blue green algae (prokaryotic groups) into separate MONERA group)

Question 13

Whittaker 1969

Answer 13

5 kingdom

Animal, plant, fungi, protista, Monera

Question 14

Woese et al 1977

Answer 14

6 kingdoms

Animal, plant, fungi, Protista, archaebacteria, eubacteria

Question 15

Woese et al 1977

How did he propose this?

Answer 15

3 domains
Bacteria, archaea, eukaryota

Based on sequencing of 16S rRNA (highly conserved so present in all domains) used to created phylogenetic relationships rather than base it on morphological similarities

Question 16

Main difference between archaebacteria and eubacteria

Answer 16

Archaebacteria usually found in extreme environmental conditions whereas eubacteria found everywhere on earth

Question 17

What are archaea?

Answer 17

Similar to bacteria in size and simplicity of structure but different in molecular organisation.

Now believed to be an intermediate between bacteria and eukaryotes.

Question 18

Wheat were archaea originally considered to be

Answer 18

Archaea appeared prokaryotic so we’re considered bacteria (they were thought to be ancient bacteria)

But then DNA sequence analysis revealed differences between archaebacteria and bacteria

Question 19

Archaea four major phyla

Answer 19

1. Phylum euryarchaeota
2. Phylum crenarchaeota
3. Phylum nanoarchaeota
4. Phylum korarchaeota

Question 20

Euryarchaeota

Answer 20

Most studied group, includes mostly methanogens (produce methane as metabolic byproduct in hypoxia conditions) and halophiles (grows in or can tolerate saline conditions)

Question 21

Phylum crenarchaeota

Answer 21

Mostly found in marine environment

Question 22

Phylum nanoarchaeota

Answer 22

Currently contains one species: Nanoarcheum equitable

Question 23

Phylum korarchaeota

Answer 23

Consists of hyperthermothiles (organism can live at high temperatures)

Question 24

What distinguishes archaea from eukaryotes and most bacteria ?

Answer 24

Presence of ether linkages in the lipids of their cytoplasmic membrane

Question 25

Prokaryotes

Answer 25

Bacteria

Archaea

Question 26

Eukaryotes

Answer 26

Plant
Animal
Fungi
Protoctista

Question 27

How related are archaea to eukaryotes ?

Answer 27

Archaea (prokaryotes) are more closely related to eukaryotes than bacteria (prokaryotes) are

Question 28

Characteristics that archaea and eukarya both have (suggests they are more closely related to eukarya than bacteria are to eukarya)

Answer 28

Methionine is initiator amino acid for protein synthesis
Lacks peptidoglycan in cell wall
Growth not inhibited by streptomycin and chloramphenicol
Histones associated with DNA
Contains several types of RNA polymerase

Question 29

Origin of eukaryotic cells theory

Answer 29

Endosymbiosis theory - some of the organelles in eukaryote were once prokaryotes that were endocytosed. (

Eg. Mitochondria and chloroplasts are the same size as prokaryotic cells and divide by binary fission + have their own circular DNA

Question 30

Gram stain results

Answer 30

Gram positive bacteria = purple = 90% cell wall made of peptidoglycan

Gram negative bacteria = pink = 10% cell wall made of peptidoglycan

Question 31

Monotrichous bacteria

Answer 31

Single flagellum at one pole

Question 32

Amphitrichous

Answer 32

Single flagella at each pole

Question 33

Lophotrichous

Answer 33

Tuft of flagella at one pole

Question 34

Peritrichous

Answer 34

Flagella all over surface

Question 35

Atrocious

Answer 35

Non-motile bacteria that lack flagellum

Question 36

How do bacteria and archaea differ

Answer 36

Bacteria cell wall has peptidoglycan, archaea cell wall does not

Bacteria cell membrane has lipid bilayer, archaea cell membrane has lipid bilayer or can have lipid monolayer

Bacteria plasma membrane lipids have fatty acids linking to glycerol, archaea plasma membrane lipids have phytanyl units linked to glycerol

Question 37

Main summary of lecture

Answer 37

• microbes everywhere
• once tools we’re available we were able to classify them
• multiple classification schemes however not until molecular approaches that we could robustly define the classifications
• began to unravel differences and similarities between eukaryotes, bacteria and archaea.