Transcript Eukaryotes
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
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
An alternative hypothesis for how the three domains of life are related
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
Giardia lamblia
Unicellular flagellate. Most commonly transmitted in the cyst form through water contaminated with human feces
Archezoans
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
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
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
Trypanosoma
, the kinetoplastid that causes sleeping sickness
The Protozoa
Ciliophora (ciliates) Stentor Move by cilia Most are free-living in fresh water
Paramecium Stentor Vorticella
Paramecium Vorticella
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
Plasmodial slime mold
Slime mold Sporangia
The life cycle of a cellular slime mold (
Dictyostelium
)
Dictyostelium
life cycle
Stages of
Dictyostelium
The life cycle of a water mold (Layer 3)
Water mold:
Oogonium
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
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
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)