The Diversity of Life I. An Overview II. An Overview of 'The Bacteria'

The Diversity of Life

I. An Overview

II. An Overview of 'The Bacteria'


I. An Overview


The key thing about bacteria is their metabolic diversity. Although they didn't radiate much morphologically (spheres, rod, spirals), they DID radiate metabolically. As a group, they are the most metabolically diverse group of organisms.


I. An Overview



A. Oxygen Demand

all eukaryotes require oxygen.


I. An Overview



A. Oxygen Demand


bacteria show greater variability:

- obligate anaerobes - die in presence of O2

- aerotolerant - don't die, but don't use O2

- facultative aerobes - can use O2, but don't need it

- obligate aerobes - require O2 to live


I. An Overview



A. Oxygen Demand


bacteria show greater variability:

- obligate anaerobes - die in presence of O2

- aerotolerant - don't die, but don't use O2

- facultative aerobes - can use O2, but don't need it

- obligate aerobes - require O2 to live

represents an interesting continuum, perhaps correlating with the presence of O2 in the atmosphere.


I. An Overview



B. Nutritional Categories:


I. An Overview




- chemolithotrophs: use inorganics (H2S, etc.) as electron donors for electron transport chains and use energy to fix carbon dioxide. Only done by bacteria.


I. An Overview





- photoheterotrophs: use light as source of energy, but harvest organics from environment. Only done by bacteria.


I. An Overview






- photoautotrophs: use light as source of energy, and use this energy to fix carbon dioxide. bacteria and some eukaryotes.


I. An Overview






- photoautotrophs: use light as source of energy, and use this energy to fix carbon dioxide. bacteria and some eukaryotes.

- chemoheterotrophs: get energy and carbon from organics they consume. bacteria and some eukaryotes.


I. An Overview



C. Their Ecological Importance


I. An Overview




- major photosynthetic contributors (with protists and plants)


I. An Overview





- the only organisms that fix nitrogen into biologically useful forms that can be absorbed by plants.


I. An Overview






- primary decomposers (with fungi)


I. An Overview






- primary decomposers (with fungi)

- pathogens


I. An Overview


III. Domain Archaea and The Early Earth


I. An Overview


III. Domain Archaea and The Early EarthThe three Archaean groups exploit extreme environments (like early Earth?):


I. An Overview


III. Domain Archaea and The Early EarthThe two Archaean groups exploit extreme environments (like early Earth?):

Crenarchaeota:

'thermacidophiles' - reduce sulphur compounds in geothermal sulphur springs and geothermal vents.


I. An Overview



Crenarchaeota:

'thermacidophiles' - reduce sulphur compounds in geothermal sulphur springs and geothermal vents.

Euryarchaeota:

'methanogens' - reduce CO2 and harvest small amounts of energy.


I. An Overview



Crenarchaeota:

'thermacidophiles' - oxidize sulphur compounds in geothermal sulphur springs and geothermal vents.

Euryarchaeota:

'methanogens' - reduce CO2 and harvest small amounts of energy.

'halophiles' - live in saline environments; some have a very primitive form of photosynthesis.


IV. Domain Eukarya

A. Characteristics

- membrane bound nucleus

- organelles

- sexual reproduction


IV. Domain Eukarya

B. Origins

infolding of membrane


IV. Domain Eukarya

B. Origins

endosymbiosis - mitochondria and chloroplasts (Margulis - 1970's)


IV. Domain Eukarya

C. Phylogeny


IV. Domain Eukarya

D. Diversity


IV. Domain Eukarya

D. Diversity

- green alga

Same chlorophyll as plants

alternation of generation

genetic analysis confirms relatedness


IV. Domain Eukarya

D. Diversity

- Choanoflagellates


IV. Domain Eukarya

D. Diversity

E. Ecological Roles

- symbiotes – wood-digesting protists in insect guts

- parasites/disease - Plasmodium (Malaria)

- productivity – 25% of NPP by photosynthetic protists (diatoms and alga)

IV. Fungi

A. Overview

1. General Characteristics

IV. Fungi

A. Overview


- multicellular eukaryotes

IV. Fungi

A. Overview



- heterotrophic

IV. Fungi

A. Overview



- heterotrophic

- absorptive nutrition:

excrete enzymes into environment and absorb the product of that digestion. They digest dead matter (decomposers) or live matter (pathogens), or may be symbiotes.

IV. Fungi

2. Classification

IV. Fungi

2. Classification

- Chytridiomycota

- Zygomycota

- Ascomycota

- Basidiomycota

Single celled members of these groups are all called “yeasts”. They are distinguished from protists based on a chitinous cell wall and absorptive (rather than phagocytic) nutrition.

IV. Fungi

3. General Biology

- The organism is composed of threadlike “hyphae”

IV. Fungi

3. General Biology- The organism is composed of threadlike “hyphae”- The hypha can be coenocytic (without divisions) or septate (with incomplete cell walls between)

IV. Fungi

3. General Biology- The organism is composed of threadlike “hyphae”- The hypha can be coenocytic (without divisions) or septate (with incomplete cell walls between)- These have a huge surface area/volume ratio for absorption.

IV. Fungi

3. General Biology- The organism is composed of threadlike “hyphae”- The hypha can be coenocytic (without divisions) or septate (with incomplete cell walls between)- These have a huge surface area/volume ratio for absorption.- The largest organisms known… 37 acres.

IV. Fungi

4. Ecological Roles

- decomposers: Fungi decompose lignin and cellulose, which most free-living bacteria can’t digest.

IV. Fungi

4. Ecological Roles

- decomposers: Fungi decompose lignin and cellulose, which most free-living bacteria can’t digest.

* antibiotics:

- Fungi and bacteria compete with one another for resources. They have both evolved chemical defenses that will kill or stop the reproduction of the other. The chemicals are antibiotics...and we use them to kill bacterial and fungal and protistan infections when they occur in the human body.

Penicillin - produced by the Penicillium bread mold.

Tetracyclins - produced by a bacteria.

IV. Fungi

4. Ecological Roles

- decomposers: Fungi decompose liginin and cellulose, which most free-living bacteria can’t digest.

* antibiotics

- mycorrhizae: fungal symbiotes of certain plants. The fungus increases the absorbance area of roots dramatically, and passes water and nutrients to the plant. The plant feeds the fungus with glucose.

- many of these fungi are more sensitive to pollutants and toxins that their host tree. For example, acid rain acidifies the soil and kills the mycorrhizae that feed spruce and fir trees. The trees die.

IV. Fungi

4. Ecological Roles


* antibiotics


- lichens – symbiote with alga

IV. Fungi

4. Ecological Roles


* antibiotics


- lichens – symbiote with alga

- pathogens – Athlete’s foot, ringworm,

yeast infections

- parasites – entomophagous fungi

IV. Fungi

D. Basidiomycetes

- bear puffballs or mushrooms as fruiting bodies

IV. Fungi

D. Basidiomycetes


- haploid hyphae fuse in dikaryotic hyphae.

IV. Fungi

D. Basidiomycetes



- these dikaryotic hyphae form the fruiting structure.

IV. Fungi

D. Basidiomycetes



- these dikaryotic hyphae form the fruiting structure.

- at the tip of each hyphae, the basidium forms, in which meiosis occurs to produce new haploid spores.

The Diversity of Life I. An Overview II. An Overview of 'The Bacteria'

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