Eukaryotes Protista

What do Eukaryotes have that Prokaryotes do not?  Membrane-bound nucleus  Mitochondria, chloroplasts, and endomembrane system  Cytoskeleton  Flagella of microtubule construction  Multiple chromosomes of linear DNA compactly arranged with proteins  Diploid life stages  Mitosis and Meiosis and Sex

Compartmentalization of functions occurs in eukaryotes

Endosymbiotic theory of eukaryotic evolution  Evidence of mitochondria and chloroplast origin –Appropriate size –Replication by binary fission –Inner membranes containing enzymes and transport systems similar to prokaryotic plasma membranes –DNA is circular and not complexed with histones –Have their own ribosomes, tRNAs and other components for transcription/translation –Ribosomes are more similar to prok. than euk.

A model of the origin of eukaryotes A model of the origin of eukaryotes

Protistan taxonomy is in a state of flux (a mess) Your Lab book and your text book approach protists in very different manners using different terminology. Your lab book is the more “classic” approach and we will follow that more closely

Traditional hypothesis for how the three domains of life are related Traditional hypothesis for how the three domains of life are related

An alternative hypothesis for how the three domains of life are related An alternative hypothesis for how the three domains of life are related

A tentative phylogeny of eukaryotes (Campbell 6 th Edition) A tentative phylogeny of eukaryotes (Campbell 6 th Edition) We are going to look at protists using a more ‘Classic”, simpler scheme

First a couple definitions  Plankton –Communities of organisms, mostly microscopic, that drift passively or swim weakly near the surface of oceans, ponds, and lakes  Encystment –Cyst formation –A response to adverse conditions –Allows a parasitic species to survive outside a host, allows others to survive hostile environmental conditions –Only some protists can do this

Archezoans  Lack mitochondria or chloroplasts  Have prokaryotic-like ribosomes  Simple cytoskeletons

Archezoans Giardia lamblia Unicellular flagellate. Most commonly transmitted in the cyst form through water contaminated with human feces

Trichomonas vaginalis An inhabitant of vaginal tract of human females. Can be sexually transmitted. Has flagella and an undulating membrane for movement

The Protozoa (animal-like protists)  Diverse group of heterotrophic protists  Classically grouped into different Phyla based upon their movement and how they feed

The Protozoa Rhizopoda – the amoebas  Very simple protists, unicellular  Pseudopodia  Entamoeba histolytica –( human pathogen)

Amoeba proteus

Use of pseudopodia for feeding Use of pseudopodia for feeding

The Protozoa Actinopoda – (Helizoans and Radiozoans)  Axopodia = projections reinforced by bundles of microtubules thinly covered by cytoplasm  Most are planktonic  Heliozoans – fresh water  Radiozoans- marine, silica shells

Actinopods: Heliozoan (left), radiolarian (right)

Radiolarian skeleton

The Protozoa Foraminifera (Forams)  Marine organisms  Porous shells of organic material hardened by calcium carbonate  Many have algae living beneath the shell which provide nutrients via photosynthesis

Foraminiferan Foraminiferan

The Protozoa Apicomplexa (Sporozoans)  All species are obligate intracellular parasites of animals  Toxoplasma gondii –Toxoplasmosis  Cryptosporidium –Diarrhea. Transmitted via fecal contamination –Water supply outbreaks have been reported  Plasmodium –Malaria

The two-host life history of Plasmodium, the apicomplexan that causes malaria

The Protozoa Zoomastigophora (flagellates)  Move by whip-like flagella  Trichonympha –Inhabits the gut of termites  Trypanosoma –Hemoflagellate –African Sleeping sickness

Trichonympha Trichonympha

Trypanosoma, the kinetoplastid that causes sleeping sickness Trypanosoma, the kinetoplastid that causes sleeping sickness

The Protozoa Ciliophora (ciliates)  Move by cilia  Most are free-living in fresh water  Paramecium  Stentor  Vorticella Vorticella StentorParamecium

Ciliates: Paramecium Ciliates: Paramecium

Fungus-like Protists  Filamentous body structure at times makes them appear to be like molds, but they are more closely related to amoebas than to true fungi.  Myxomycota (plasmodial slime molds)  Acrasiomycota (cellular slime molds)  Oomycota (water molds, white rusts, downy mildews)

The life cycle of a plasmodial slime mold, such as Physarum The life cycle of a plasmodial slime mold, such as Physarum

Plasmodial slime mold Plasmodial slime mold

Slime mold Sporangia Slime mold Sporangia

The life cycle of a cellular slime mold (Dictyostelium) The life cycle of a cellular slime mold (Dictyostelium)

Dictyostelium life cycle Dictyostelium life cycle

Stages of Dictyostelium

The life cycle of a water mold (Layer 3) The life cycle of a water mold (Layer 3)

Water mold: Oogonium Water mold: Oogonium

Powdery mildew Powdery mildew

Algae  Diverse group of photoautotrophic aquatic organisms  Major role in aquatic food chains  Fix carbon dioxide into organ carbon  Produce somewhere between 50% and 80 % of the Earth’s oxygen

Algae Dinoflagellata (dinoflagellates) –They have two flagella and may have armor (cellulose plates) or may be naked (without armor). Dinoflagellates have pigments and can carry on photosynthesis. Major component of phytoplankton. –Gonyaulax  Red tide  Paralytic shellfish poisoning –Peridinium (lab) –Noctiluca miliaris  Bioluminescent

Dinoflagellate Dinoflagellate

Dinoflagellates

Swimming with bioluminescent dinoflagellates

Algae Bacillariophyta (Diatoms)

a diatom, a unicellular "alga"

Chrysophyta Golden algae

Phaeophyta (Brown algae)  Largest and most complex of the algae  Kelp is a brown algae –Giant kelp - up to 100 meters in size  Seaweeds = large, multicellular marine algae of coastal waters which include members of the Brown, Red, and Green algae groups

Australian bull kelp (Durvillea potatorum)

Kelp forest

Red algae: Dulse (top), Bonnemaisonia hamifera (bottom) Rhodophyta Red Algae

Chlorophyta (green algae)  Over 7000 species known –Freshwater and marine –Unicellular and multicellular forms  Chlamydomonas  Volvox  Spirogyra  Cladophora  Lichens=a mutualistic relationship between a green algae and a fungus

Colonial and multicellular chlorophytes: Volvox (left), Caulerpa (right) Colonial and multicellular chlorophytes: Volvox (left), Caulerpa (right)

Chlamydomonas

Volvox

Spirogyra

Chladophora

Lichens