Origin of Eukaryotes

-some question the endosymbiotic origin (aka fusion hypothesis) as the main driver behind it-evidence from the PVC superphylum (superphyla of bacteria), which shares many features w/ Eukarya (and not necessarily w/ Archaea) -therefore this superphyla may have served as ancestrial "stock" -& the evolution of the many major features of Eukarya may have been present in some Bacteria & evolved in steps

Essential role of Prokaryotes

1. Decomposers2. Symbiotic relationships (mutualistic) ex: 500-1000 species in our intestines that help w/ digestion

Prokaryotes Impact On Humans (Bad)

1. 1/2 of all human parasites are bacteria (deadliness caused by toxins)2. Can be used as bioterrorism agents (ex: anthrax)3. Difficult to defeat given rapid evolution

Prokaryotes Impact on Humans (Good)

1. Fermentation for food2. Research3. Genetic modification & bioengineering4. Bioremediation-remove pollutants from the environment (ex: oil spill in Gilf of Mexico)5. Decomposers6. Mutualistic symbiosis7. Provide scenic landscapes8. Oxygenation of the Earth

Protists (Eukarya 2.1 bya origin)

General Characteristics

-mainly unicellular-mainly aquatic-some asexual, some sexual, some both-they are all Eukaryotes

Protists-Origins: Why so diverse?

Endosymbiosis (process of engulfing cells that become endosymbionts & ultimately organelles/plastids)

Primary Endosymbiosis

One heterotrophic Eukaryote engulfs a photosynthetic cyanobacterium

Secondary Endosymbiosis

Red or green algae being engulfed by another Eukaryote

Diplomonadida (Giardia) & Parabasalas (Trichomonas)

-Lack plastids-Mitochondria lack DNA


Spiral or crystalline rod at base of flagella

A) Kinetoplastids (Trypanosoma)B) Euglenids (Eugela) -Photosynthesis or be heterotrophs

Alveolates & Stramenopilans

Red algae symbiont


Membrane bound sacs just under plasma membrane (unknown function)

ex: Dinoflagellates, Apicomplexans (Plasmodium-malaria), Cilliates (Paramecium)


Hairy flagellum and smooth flagellumex: Oomycetes, Golden Algae, Diatoms, Brown Algae

1. Brown Algae & "Seaweed"

-seaweed = some type of algae that have specialized tissues & "organs" like those seen in plants, but they have evolved independentlyex: Alternation of generations Multicellularity & Tissue formation Larger in size w/ parts (holdfast, stipe, blades)

Cercozoans & Radiolarians

Move by threadlike psuedopodia

A) Cercozoans (Forams-CaCO3 shells)B) Radiolarians (SiO2 shells)


-amoebas w/ lobe shaped psuedopodia-these are thought to be the closest relative to the Fungi & Anamalia
ex: Gymnoamoebans, enamoebans & slime molds

Rhodophyta (Red Algae)

-Chlorophyll a-endosymbiotic event w/ a cyanobacterium--->led to chloroplasts

Rhodophyta (Red Algae)

-phycobillins-some "seaweeds"

Green Algae (Chlorophyta & Charophyta)

-Carotenoids-Chlorophyll b i. chlorophyta ii. charophyta (stoneworts) -sister group to plants

Synapomorphies Charophyta share w/ Plants

1. Similar percentage of cellulose in their cell walls2. Peroxisome enzymes that minimize loss of organic products3. Similar structure to their flagellated sperm4. Similar chloroplast DNA5. Formation of phragmoplast (scaffold for formation of the cell plate at the end of a miotic division