Chapter 28: The Protists
Objectives
1.
Most Eukaryotic Organisms
are Multicellular
2.
Realize Protista is
Paraphyletic and no longer
one single kingdom
3.
Will understand
Endosybiosis
4.
Understand the variety of
protists
5.
Understand some
ecological relationships of
protists
Basics structures and functions of Protists
-Recently found to be Paraphyletic – Diverse - Some protists are more closely related
to plants, fungi, and animals then they are to other protists
-Exceptions to almost all characters
-Most are unicellular
-Many contain specialized organelles (Contractile vacuoule)
-Mixed nutritional means. (Photo, Hetero, and Mixo)
-Asexual and Sexual reproduction (3 basic types)
-Contain membrane bound organelles
Endosymbiosis
-Evidence suggests Eukaryotic
cells arose by endosymbiosis
-Mitochondria were thought to
have been the first endosybiont
-Cyanobacteria were thought to
be the next – Photosynthesis
-Secondary endosymbiosis is
when a Eukaryotic cell engulfs
another Eukaryotic cell.
p. 576
Current Understanding
of Eukaryotic
Organisms
1.
5 super groups of
Eukaryotic organisms
2.
Some protists are
more closely related
to animals then other
protists.
3.
Changes have come
about due to better
understanding of
DNA, Cellular
Components, and
Cellular Chemistry
Excavata
-Made up of three monophyletic groups
1. Diplomonads
2. Parabasalids
3. Euglenozoans
-Most have flagella – extensions of
microtubules
-Diplomonads and Parabasalids have highly
reduced mitochondria – No electron transport
chain and can’t use Oxygen.
-Euglena are mixotrophs
Chromaveolates
-Most diverse group of protists
-Thought to be monophyletic (DNA evidence)
-Origin was secondary endosymbiosis with a red algae
-Group includes:
1. Dinoflagellates (Red Tide)
2. Apicomplexan (Malaria)
3. Ciliates (Cilia – Paramecium)
4. Stramenophiles (Diatoms)
5. Golden Algae (Yellow/brown Caratenoid pigments)
(Some are multicellular)
6. Oomycetes (Water molds)
Rhizaria
-Ameobas are not
monophyletic
-Ameobas that belong to
the Rhizaria group have
thread like pseudopodia
Archaeplastida: Red and Green Algae
-Group contains land plants
-Algae protists are the closest relative to plants
-Chloroplatasts are similar to land plants
-Use of Alternation of Generation much like land plants (p. 592)
Unikonta
-Group contains both Animals and Fungi
-Includes Slime molds
-Other closely related protists are discussed
in the animal chapter.
-Molecular and DNA evidence is the reason
for going away from the protista kingdom