Eukaryotes: Protista



Origin of the nucleus and endoplasmic reticulum. Fig 20.1


Endosymbiosis. Fig 20.2

- Mitochondria

- Chloroplasts


Evolution of mitosis and sexual reproduction


asexual reproduction. Fig 20.3

parthenogenses. Image Image2


cross-fertilization. Image  Image2


Eukaryotic organisms have:

- a true nucleus

- membrane-enclosed organelles

- "9+2" flagella and cilia. Most have flagella or cilia. Fig. 5.21a. image  Movie!

- Unicellular, colonial, multicellular


Kingdom Protista is artificial grouping. Fig 20.7   Table 20.1

- Classification does not represent evolutionary relationships

Heterotrophs with cytoplasmic movement

Amoebas. Fig 20.8


Forams. Fig 20.9

Radiolarians. Fig 20.10

Heterotrophs with flagella


- parasitic ex: Trypanosoma (African Sleeping Sickness)

- choanoflagellates are likely ancestors of all animals



- use cilia for movement and food capture. Fig. 20.12

Heterotrophs with restricted movement. Fig. 20.13

Cellular slime molds

Plasmodial (acellular) slime molds

Water molds

Photosynthetic protists

The endosymbiotic model suggests chloroplasts originated at least three separate times from different prokaryotic endosymbionts.


Dinoflagellates. Fig 20.14

- both autotrophs (photosynthetic) and heterotrophs (parasites and predators)

- Most with cellulose and silica plates

- Two flagella

- Many mutualistic with corals

- algal blooms and red tides.


Euglenoids. Fig 20.16



- Diatoms are mostly unicellular organisms with overlapping glasslike walls of silica.

           - diatomaceous earth: White Cliffs of Dover


Golden algae


Red algae. Fig 20.18


Green algae (single-celled). Fig. 20.19

- Chlorophyll a, chlorophyll b

- In same taxonomic category as the multi-celled green algae below


Green algae (multicellular). Fig 20.20

- Similarities in chloroplasts & DNA and RNA sequence analysis indicate that green algae are the ancestors  of all plants

- have similar cell division to higher plants - cell plate formation. Image


Brown algae. Fig 20.21

- Many seaweeds (including kelp and Sargassum)

- cultivated for food

Heterotrophs: non-motile spore formers


Plasmodium causes malaria. Fig 20.22

       200 million people per year get infected in Africa alone; at least 2 million die per year