Introduction: the Protists Introduction to Protists (Cont.) Cilia and Flagella

Introduction to the Protists: Introduction to the Protists: Protozoa Protozoa

1. Introduction

2. Euglenozoans

4. Amoebozoans

Protists: Very Diverse and Introduction: The Protists Successful

• In the past, all protists were grouped together • More structural and functional diversity than in the Kingdom “Protista” any other group of organisms • “Protist” is now used to refer to organisms that are neither plant, animal, nor fungi • Most unicellular; some colonial or multicellular

• “Paraphyletic”: protists represent a diverse group of organisms from many evolutionary • Single cells, but very complex lineages – Diverse cellular functions – Very specialized organelles – Compare to “monophyletic” lineages

Introduction to Protists (cont.) Cilia and Flagella

• Cilia •Nutrition: autotrophs, heterotrophs, mixotrophs – Usually occurs in large numbers on cell surface; short – “back and forth” motion • Habitats: Most aquatic, some terrestrial; important as plankton • Flagella – One or a few per cell; long • Reproduction: some asexual, most – Undulatory motion sexual

1 Cilia and Flagella: Motion Flagella and Cilia: “9 + 2” Structure

Fig 6.23 Fig 6.24

Introduction to Protists: Protozoa Euglenozoans

1. Introduction • Diverse group that contains predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites 2. Euglenozoans • Characterized by unique rod-like 3. Alveolates structures in flagella

4. Amoebozoans • Some examples: Euglena, Trypanosoma

Euglena: Mixotrophic Trypanosoma: Sleeping Sickness

Fig 28.8 Not In Text

2 Trypanosoma: Sleeping Sickness Introduction to Protists: Protozoa

1. Introduction

2. Euglenozoans

3. Alveolates

Fig 28.7 4. Amoebozoans

Alveoli: Unique Structures in Cell Alveolates Membranes of the Alveolates

• Characterized by membrane-bound sacs (alveoli) just under the plasma membrane

• Function of alveoli unknown – May stabilize cell surface – May be involved in osmoregulation

• Some examples: Paramecium, Plasmodium

Paramecium: A Ciliate Plasmodium: Malaria

Fig 28.11 Fig 28.12

3 Introduction to Protists: Protozoa Amoebozoans

• Many species of amoeba have lobe-shaped 1. Introduction pseudopodia

• Entamoebas: Parasites that cause amebic 2. Euglenozoans dysentery in humans

• Gymnamoebas: common in soil, freshwater, 3. Alveolates and marine habitats – Most are heterotrophs that feed on bacteria and other protists 4. Amoebozoans

An Amoeba Feeding

Fig 28.24