Chapter 28~ The Origins of Eukaryotic Diversity

Protists

Ingestive (animal-like); protozoa

Absorptive (fungus-like)

Photosynthetic (plant-like); alga

The Endosymbionic Theory

Mitochondria and chloroplasts were formerly from small prokaryotes living within larger cells (Margulis)

Protist Systematics & Phylogeny, I

1- Groups lacking mitochondria; early eukaryotic link; Giardia (human intestinal parasite; severe diarrhea); Trichomonas (human vaginal infection)

2- Euglenoids; autotrophic & heterotrophic flagellates; Trypanosoma (African sleeping sickness; tsetse fly)

Protist Systematics & Phylogeny, II

Alveolata : membrane-bound cavities (alveoli) under cell surfaces; dinoflagellates (phytoplankton); Plasmodium (malaria); ciliates (Paramecium)

Ciliophora (ciliates)

Ciliates

Use cilia for movement and feeding

Mostly freshwater

Macronucleus and micronuclei

Subunits in macronucleus – everyday act.

Conjugation: Meiosis and syngamy

Binary fission

Protist Systematics & Phylogeny, III

Stamenophila : water molds/mildews and heterokont (2 types of flagella) algae; numerous hair-like projections on the flagella; most molds are decomposers and mildews are parasites; algae include diatoms, golden, andbrown forms

Protist Systematics & Phylogeny, IV

Rhodophyta : red algae; algin, agar, no flagellated stages; phycobilin (red) pigment

Chlorophyta : green algae; chloroplasts; gave rise to land plants; volvox, ulva

Phaeophyta (brown algae)

Large seaweeds

Thallus (sprout), stipe (stem), holdfast (root), blade (leaf)

Agar – thickener, lubricant, culture media

Protist Systematics & Phylogeny, V

Affinity uncertain:

Rhizopods: unicellular with pseudopodia; amoebas

Actinopods: ‘ray foot’ (slender pseudopodia; heliozoans, radiolarians

Protist Systematics & Phylogeny, VI

Mycetozoa : slime molds (not true fungi); use pseudopodia for locomotion and feeding; plasmodial and cellular slime molds

Cellular slime mold
ß

Protists to Know

K. Archaezoa

Heterotrophic flagellates, that are parasitic, symbionts, or free-living

Termite flagellates

Trypanosoma (African sleeping sickness, Chaga’s disease, Nagana)

Giardia

K. Euglenozoa

Flagellated, autotrophic/heterotrophic, common in polluted areas

Euglena

Protists to Know II

K. Alveolata

Dinoflagellates: producers, toxin, bioluminesce, red tide algae

Gonyaulax , Pfiesteria

Sporozoans: parasitic

Toxoplasma (toxoplasmosis)

Plasmodium (malaria)

Ciliophora (Ciliates): heterotrophic, have cilia, very complex [contractile vacuoles, gullet, anal pore, trichocysts, macronuclei

Paramecium

Rhizopods (amebas, amoebae): heterotrophic, pseudopodia

Foraminiferans, radiolarians, heliozoans

Protists to Know III

K. Alveolata

Myxmycota (slime molds)

K. Stramenophila

Bacillariophyta (diatoms): silica cell walls

Chrysophyta (golden algae): photosynthesize, engulf

Oomycota (egg molds): resemble fungi, have filaments (hyphae), cellulose cell wall, differentiation of gametes (eggs and sperm), sexual and asexual cycle

Phaeophyta (brown algae): brown pigment (fucoxanthin), marine, cold water, specialized tissues (holdfasts, stipes, blades, bladders, thallus), agar

Protists to Know

K. Rhodophyta (red algae)

Mostly marine, absorb blue light, agar

K. Chlorophyta (green algae)

Use chlorophyll, alternation of generations, symbiotics in lichens, and with some other protists and invertebrates (green hydra), cellulose cell walls, probably gave rise to land plants

Volvox, Ulva, Ulothrix