Protists

Chapter 28

Protists

Eukaryotes Not plants, fungi or animals

Protists

Unicellular Colonial Multi-cellular Highly variableNo one unifying feature“protist” informal term Greatest diversity of eukaryotic kingdoms.

Endosymbiosis

Cyanobacterium

Heterotrophiceukaryote

Over the courseof evolution,this membranewas lost.

Red alga

Green alga

Primaryendosymbiosis

Secondaryendosymbiosis

Secondaryendosymbiosis

Secondaryendosymbiosis

Plastid

Dinoflagellates

Apicomplexans

Stramenopiles

Plastid

Euglenids

Chlorarachniophytes

General biology

Cell surfaceLocomotion organellesCyst formationNutrition Reproduction

Cell surface

Varies Only cell membraneExtra cellular material (ECM) on outside of membraneECM makes a strong cell wall Diatoms shells of silica

Locomotion organelles

Varies Flagella (1 or more)Several shorter called cilia Pseudopodial (false feet)Lobopodia-blunt extensionsFilopodia-thin branch extensionsAxopodia-supported by microtubules

Cyst formation

Protective coveringIn adverse environmentsDormant forms

Nutrition

Phototrophs (photosynthetic)HeterotrophsMixotrophs Combine photosynthesis with heterotrophic nutritionPhagotrophsIngest visible particles of foodOsomotrophsIngest soluble food

Reproduction

Asexually– Binary fission– Budding

Sexual reproductionGamete meiosisSpore-producing protists are haploid as adultsAlgae alternate haploid/diploid

Fig. 28-23

Commonancestorof alleukaryotes

DHFR-TSgenefusion

Unikonta

Excavata

Chromalveolata

Rhizaria

Archaeplastida

Choanoflagellates

Animals

Fungi

Amoebozoans

Diplomonads

Euglenozoans

Alveolates

Stramenopiles

Rhizarians

Red algae

Green algae

Plants

RESULTS

Categories

1. Excavata2. Chromalveolata3. Rhizaria4. Archaeplastida5. Unikonta

1. Excavata

DiplomonadsParabasalidsEuglenozoans

CDC

Diplomonads

Giardia lamblia (parasite)Flagellate protistMitochondria lacking DNA, ETC or enzymes for citric acid cycleAnaerobic environmentFound in waterCause diarrhea“hikers diarrhea”

Parabasalids

TrichomonadsReduced mitochondriaAnaerobic energy production T. vaginalisInfects vaginal liningDisrupts normal acidity of vagina

Euglenozoans

AutotrophsHeterotrophsParasites

Euglenozoans

EuglenoidsMixotrophs Earliest free-living eukaryotesFresh waterMove by flagellumAsexually

Euglena

Euglenozoan

KinetoplastidsSingle mitochondria2 types of DNAParasitesTypanosomiasis African sleeping disease

2. Chromalveoletes

Alevolates– Dinoflagellates– Apicomplexans– Ciliates

Stramenopiles– Diatoms– Golden algae– Brown algae– Oomycetes

Dinoflagellates

Alveolata

Common traitAlveoli (membrane sac) Space below plasma membraneDinoflagellatesApicomplexesCilliates

Dinoflagellates

PhotosyntheticMarine & freshwaterCharacteristic shapeReinforced by internal plates of cellulose.Two flagella sit in perpendicular grooves in the “armor” Produce a spinning movement“red tide” produced with large growth

Apicomplexes

Spore forming parasitesSpores pass from host to hostApical complexes:Organelles-one of cellPlasmodium causes malariaMosquito to human

Plasmodium

Malaria

Toxoplasma gondi

Ciliates

Large numbers of ciliaAnchored to microtubules below membrane2 nuclei Macronucleus for mitosisMicronucleus for sexual reproduction

Paramecium

Paramecium

Ciliates

Paramecium

Stramenopila

DiatomsBrown algaeGolden algaeOomycetes

Diatoms

Unique glasslike walls Hydrated silica in an organic matrix.Overlap like a shoe box & lid.PhotosyntheticMostly unicellular

Diatoms

Brown algae

Largest algae (kelp)MulticellularMost are marineFound in cooler watersColor due to carotenoids Alternate between diploid & haploid cyclesThickens foods (ice cream, pudding)

Brown algae

Golden algae (Chrysophyta),

Named for the yellow & brown carotene Xanthophyll pigmentsTypically bi-flagellated.Many freshwaterMost are unicellular, some are colonial.Poor environment;Form resistant cysts-viable for decades.

Golden algae (Chrysophyta),

Oomycetes

Cellulose in cell wallsMostly diploidFlagellated cellsCaused the potato blight in 1845-47Turned potato plants to black slime

3. Rhizaria

AmoebasForamsRadiolarians

Amoebas

PseudopodsFlowing extension of cytoplasmPulls amoeba forwardCauses dysentery

Amoebas

Forams

Almost all marine.Most live in sand or attach to rocks or algae.Some are in plankton.Multi-chambered, porous shells Consists of organic materialsHardened with calcium carbonateTests

Forams

Radiolarians

MarineInternal skeleton made of silicaSkeleton lines seafloor when dies

200 µm

Radiolarians

4. Archaeplastida

Red algaeGreen algae

Rhodophyta

Red algaeMicroscopic to large seaweed on beachMostly multi-cellularWarm coastal watersUsed in sushi

Red algae

Chlorophyta

Green algaeGreen chloroplastsSimilar to plantsDiverged recentlyMostly live in fresh waterUnicellular to multi-cellular

Green algae

5. Unikonta

Slime moldsChoanoflagellida

Slime molds

Looks like a moving mass of slimePlasmodiumA multinucleated mass of cytoplasmMove as a mass called a slugDigest bacteria, yeasts & other small organic particlesMulti-cellular & unicellular

Slim molds

Slim molds

Slim molds

Slim mold

Choanoflagellida

Similar to spongesFreshwaterSingle flagellumFeed on bacteria

Fig. 28-UN6