Membrane-bound nucleus present

Extensive endomembrane system

Numerous cell organelles

Linear chromosomes (DNA) - located within nucleus

Cell division involves mitosis and meiosis (reproduction)

Theory of serial endosymbiosis proposes that mitochondria and chloroplasts in eukaryotes were formerly small prokaryotes living symbiotically within larger cells

In primary endosymbiosis, certain cells first acquired ancestors of plastids by engulfing cyanobacteria

In secondary endosymbiosis, heterotrophic protist engulfed alga containing plastids - eventually became one and same organism

Most diverse of all eukaryotes - both unicellular and multicellular forms

Recent changes in classification based on new knowledge involving phylogenetic relationships

Kingdom Archaezoa split into two clades - the diplomonads (Diplomonadida) and the trichomonads (Parabasala)

Plasmodial and Cellular Slime Molds placed on separate lineage (Mycetozoa)

Lack mitochondria - may represent the earliest lineages of eukaryotes - polyphyletic group - do not appear to have evolved from a common ancestor

Includes 3 groups - the diplomonads, the trichomonads and the microsporidians - all parasitic

Protists with flagella - commonly called flagellates (not formal taxon) - both autotrophic and heterotrophic organisms - monophyletic group

Euglenoids - autotrophic and heterotrophic forms - includes Euglena - the microbe commonly used in lab demonstrations

Kinetoplastids - symbiotic organisms - includes important parasites (e.g., Trypanosoma - causal factor of African sleeping sickness)

Characterized by small membrane-bound cavities (alveoli) under cell surfaces - monophyletic

Dinoflagellates - unicellular w/ 2 flagella - whirl - mutualistic and parasitic associations - "blooms" of Pfiesteria implicated in red tides - toxic to fish

Apicomplexans - all parasitic - complex life cycles w/ multiple hosts - Plasmodium causal factor of malaria - vectored by Anopheles mosquito

Ciliates - cilia for locomotion - Paramecium

Photosynthetic autotrophs and heterotrophs w/ hairlike projections on flagella - monophyletic

Diatoms - aquatic - walls of silica - phytoplankton - accumulate in massive layers of sediments - diatomaceous earth

Golden algae -freshwater & marine - pigmented

Water molds - heterotrophic - aquatic & terrestrial - resemble fungi, but have cellulose in wall - most are decomposers - many important plant parasites (e.g., white rusts & downy mildews)

Brown algae - largest stramenopiles - seaweed

Known as red algae - have no flagellated stages in life cycle - monophyletic group

Reddish coloration due to accessory pigment known as phycoerethrin - not all reddish

Primarily marine - some freshwater and terrestrial forms - commonly known as seaweeds

Named for green chloroplasts - photosynthetic - very closely related to plants - monophyletic

Includes unicellular and multicellular forms - aquatic - most in fresh water - some marine - seaweeds

Important components of plankton - others form symbiotic relationships - e.g., lichens - mutualistic relationships between green algae and fungi

Complex life histories - both sexual and asexual reproduction - exhibit alternation of generations

Includes brown, red and green algae - evolved independently

Inhabit subtidal and intertidal zones in coastal waters - harsh environment - alternate submersion and exposure

Structural adaptations - thallus (body) consisting of holdfast (resemble roots), stipe (stem) and blades (resemble leaves) - blades with floats - slippery blades - similarities due to convergent evolution

Unicellular eukaryotes that move by means of pseudopodia - all appear to be polyphyletic groups

Rhizopods - amoebas - Entamoeba - amoebic dysentery

Actinopods - Heliozoans & Radiolarians - skeleton internal - form deep sediments

Foraminiferans - Forams - multichambered cells - - form deep sediments - good index fossils

Plasmodial and Cellular Slime Molds - resemble fungi (result of convergent evolution) - important as decomposers

Under relatively mild conditions - tend to reproduce asexually

Under relatively harsh conditions, may revert to sexual reproduction - formation of resistant stage

Alternation of generations - occurs in algae

Complex life cycles involving the alternation of multicellular haploid forms (gametophyte) and multicellular diploid forms (sporophyte) - each produces the other in cyclic manner

Occurs widely among the brown, red & green algae - may be isomorphic (gametophytes & sporophytes structurally similar) or heteromorphic (gametophyte & sporophyte structurally different)

Not the same as alternation of haploid and diploid conditions in sexual cycles - e.g., meiosis)