Protists: eukaryotes, not plants, fungi, or animals
Historically classified as Kingdom Protista, but DNA sequencing showed diversity, so not a kingdom
Classification:
Animal-like: Protozoa
Plant-like: Algae
Fungal-like: Slime molds and water molds
Focus: Protozoa (Animal-like Protists)
Chemoheterotrophs
Many are motile
Ingestive nutrition
Lack cell walls
Specific Protozoa Examples
Amoeba Proteus
Found on slides 23 and 24 in microbee box
Unicellular, lacks cell wall
Pseudopods (cytoplasmic extensions) for:
Motility
Phagocytosis (food acquisition)
Structure Identification:
Nucleus (chromosomal DNA)
Pseudopods
Contractile vacuoles (pump out excess water)
Habitat: freshwater, oxygen-rich environments
Delicate, often found under lily pads
Can form cysts in tough conditions
Euglena
Found on slides 25 and 26 in microbee box
Myxotrophs: both photoautotrophs and chemoheterotrophs
Secondary endosymbiosis: acquired chloroplasts from algae
Structures:
Long and short flagella
Nucleus
Contractile vacuoles
Pellicle (protein plates)
Stigma (eyespots for phototaxis)
Movement: spiral motion, phototaxis
Paramecium
Ciliate: covered with cilia for motility and food acquisition
Food acquisition through phagocytosis, using a gullet
Chemoheterotrophs
Symbiosis with green algae in some species
Two nuclei:
Macronucleus
Micronucleus (involved in sexual reproduction)
Contractile vacuole
Processes in Protists
Endocytosis & Phagocytosis: bringing substances into the cell
Exocytosis: expelling waste materials
Next Steps
Future videos will cover symbiotic protozoa and pathogenic examples like Entamoeba histolytica (causes amoebic dysentery), Giardia, Trypanosoma, and Plasmodium.