Lecture Notes on Protists Overview

Oct 16, 2024

Lecture on Protists

Introduction

  • Discussion on lab chapter 20: Protists
  • Mention of a protist worksheet

Protists Overview

  • 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.
  • Aim to discuss symbiotic relationships in detail.