1. The Protists
Although the protists are single-celled organisms like bacteria, they are distinct. Protists are eukaryotes,
which are distinct from the prokaryote bacteria.
Prokaryotes Eukaryotes
Organelles No organelles. Cytoplasm Membrane-surrounded
contains ions, enzymes and organelles (e.g. mitochondria,
ribosomes chloroplasts) carry out important
functions
DNA Single chromosome DNA located Nucleus is surrounded by a
in nucleoid with no membrane membrane and may contain
several chromosomes
Metabolism Chemical reactions (e.g. Chemical reactions carried out in
respiration) carried out in the specialized organelles
cytoplasm.
Structure Smaller (2 um) Larger (10 – 100 um)
The single-celled Protiska kingdom has 115,000 species of extreme diversity
Animal-like (prtotzoans)
1. Zooflagellates
a. Possess flagella for moving in water
b. E.g. Trypanosoma (sleeping sickness)
2. Amoebas
a. No set shape; use pseudopods to engulf food (endocytosis)
b. May be parasitic (e.g. Entamoeba)
3. Ciliates
a. Covered in cilia for propulsion
b. Paramecium feeds by sweeping food into the oral groove
c. Undergo asexual & sexual reproduction
4. Sporozoans
a. Produce spores during asexual phase
b. Parasitic (they feed off a host [e.g. plasmodium, which causes malaria])
Fungus-like
1. Acellular Slime Molds
a. Wall-less mass of cytoplasm (plasmodium)
b. Produce fruiting bodies (spores) by meiosis to travel
2. Cellular Slime Molds
a. Move as amoeba when fed; otherwise form fruiting bodies for spores
3. Water Molds

2. Plant-like
Many protists contain chlorophyll & carry out photosynthesis
1. Euglenoids – Draw
a. Can feed as autotrophs (sunlight) or heterotrophs (organic material)
2. Algae
a. Contain chloroplasts and carry out photosynthesis
b. Diatoms: silica shells; key food source in oceans
c. Dinoflagellates: produce toxins in shellfish (red tide)
d. Green Algae: single celled or multicellular but simpler than plants; contain cellulose;
carry out >50% of photosynthesis on Earth