Protists are a diverse group of eukaryotic organisms that are not classified as plants, animals, fungi, or prokaryotes. They include single-celled and multicellular organisms that may be photosynthetic, heterotrophic, or parasitic. The endosymbiotic theory proposes that eukaryotic cells originated from prokaryotic cells engaging in endosymbiosis. Protists are classified into 5 candidate kingdoms based on genetic and cellular structure similarities. They display a wide variety of morphologies and behaviors.

1. Chapter 20: Protists
Name___________________________________ Period_____________
• What is a Protist?
o _______________________ cell
o Most protists are _____________________ but some are ______________________
o Not members of the kingdoms ________________________________________________________
o Protists are a diverse group that may include more than ______________ species
• Origin of Eukaryotic Cells
o ___________________________ bacteria evolved in the seas of the Precambrian
o By 2.2 bya, _______________ filled the water, and the Earth rusted
o ________________began accumulating in the atmosphere, and the sky turned_____________…in
several hundred million years
o Precambrian Seas (figure)
o With all the oxygen in the atmosphere, ________________________________ evolved as a more
efficient method of organic energy use
o Prokaryotes that used this new form of metabolism began evolving __________________________
o By _______________ eukaryotes’ ancestor had evolved
Endosymbiotic theory
o Theory that eukaryotic cells
o Arose from ________________________ formed by prokaryotic cells
o Formed from a ____________________among several different prokaryotic organisms
o By __________________________________, Boston University
o Evidence: mitochondria and chloroplasts are similar to bacteria
 _____________________________
 _____________________________DNA
 _____________________________structure
 Divide by _____________________________
 __________________________&________________________________machinery

2. Compare and Contrast
Characteristic Prokaryotes Eukaryotes
Genes
Cell Wall
Membrane bound
organelles
Flagella

3. • Classification of Protists
o Protists are so diverse that biologists suggest that they should be broken up into several kingdoms
o Polyphyletic, two or more ancestors
 _______ sequencing
 _________ structure
o Currently five candidate kingdoms (Others listed do not yet have suggested kingdoms.)
 Candidate Kingdom: Archaezoa
Lack _____________________________
_____________________________ similar to prokaryotes
Diplomondida
o _____________________________
o Free-living and commensal
o Giardia--parasite
 Giardiasis—Hiker’s diarrhea
 Candidate Kingdom: Euglenozoa
All _____________________________
Euglenozoa
o ______ flagella
o _____________________________: chlorphylls a and b
o Euglena
 Euglena movement
Kinetoplastids
o _____________________________flagella
o parasites
o Trypanasoma—_____________________________
 Candidate Kingdom: Alveolata
Alvoeoli—small cavities under cell surface
_____________________________ or
_____________________________
Dinoflagellates
o Dinoflagellate ceratium
o _____________________________
Apicomplexans
o Apicomplexan—Plasmodium
o _____________________________
Ciliates
o Paramecium caudatum
Vorticella sp.

4.  Protists with _____________________________
Motile
o “False Feet” extension of cytoplasm & cell membrane
_____________________________
o Feed on algae, bacteria and other protists
o Detritvores
o Parasites
Rhizopods--Amoebas
Actinopods
o Heliozoan
o Radiozoan
Foraminifera
 Candidate Kingdom: Stramenopila
Algae
o Photosynthesis, but use Chlorophyl _____ not_____ as in plants
o Store energy in a different starch
o Diatoms
o Golden algae
o Brown Algae
Oomycetes
o _____________________________
 Absorptive nutrition & parasitic
o Cell walls _____________________________, not chitin as fungi
o _____________________________cells, absent in fungi
 Water Molds
Achlya
 Downy mildews
Phytophythora infestans Potato Blight caused
_____________________________in Ireland, 1845-51
 Plant rusts
Plasmopara viticola

5.  Candidate Kingdom: Rhodophyta
Red Algae
No _____________________________flagella, ever
Photosynthetic
o Phylocobilin pigments, absorb _________________________of deep waters
o Store energy as “Floridean starch”
Cell walls with agar & carageenan
Human Uses
o _____________________________
o _____________________________
 Chlorophyta—Green Algae
Photosynthetic
Chlorophyl __________________________________________________________
Storage as _____________________________
Mutualistic, _____________________________
Ancestors of modern plants
o Sometime included in _____________________________
Sprirophyta
Volvox
Ulva
Phytoplankton
o The population of small _____________________________ organisms near
the surface of the ocean
o About _____________________________on earth occurs in phytoplankton
Algal Blooms
o Sometimes populations of algae grows in enormous masses
o deplete the water of _____________________________ and can
_____________________________ the water

6.  Fungus-like Protists: Slime Molds
Like fungi,
o _____________________________, decomposers
o _____________________________
Unlike fungi
o Have centrioles
o Lack _____________________________cell walls
Myxomycota: Plasmodial Slime Mold
o A _____________________________-like protoplasm that contains
_____________________________within a single cell membrane
o When food grows scarce, they stop moving and grow
_____________________________.
Dictyosteliomycota : Cellular Slime Mold
o live as _____________________________-like cells moving about feeding on
bacteria.
o When food becomes scarce, they combine into a ____________
______________________________________________.
o This migrates to a new area before developing into a ____________
________________that produces and releases spores.
o Each spore then develops into a _____________________________-like cell.