Protists - Rochester Community Schools

Protists The first Eukaryotes Origin of Eukaryotic Cells Endomembrane system- developed Endomembrane system- developed

from infolding of plasma membrane. Evolutionary advantage? compartmentalization, microenvironments, increased membrane surface area Endosymbiotic Theory

Inside together living. Plastids and mitochondria are a result of the endocytosis of bacteria by larger cells of the lineage that become eukaryotes. All eukaryotes got mitochondria only some got chloroplasts. Endosymbiotic Theory Evidence

1) C & M have their own DNA

( circular, no histones) 2) C & M have their own ribosomes (small like bacteria) 3) C & M have 2 membranes (outer like eukaryote, inner like bacteria) (homologous transport proteins) 4) C & M replicate on their own 5) Endosymbiosis observed where prey or

parasites become mutualistic symbionts Secondary endosymbiosis of red or green algae create chloroplasts with 4 membrane layers Endosymbiotic Algae Importance of Protists

Large component of photosynthetic plankton Diatoms, dinoflagellates, Many are Endosymbionts

Cause human disease: Giardia (hikers diarrhea), Trichomonas (STD), Trypanosoma (sleeping sickness), plasmodium (malaria),

Protists = Eukaryotes that are not Plant, Animal or Fungus 1) Most are unicellular 2)

None have true tissues (so not plant, animal or fungi) 4) Some animal-like(ingest food), some plantlike(photosynthetic ) some Fungus-like (saprobes) 5) Paraphyletic group so not a kingdom

(share a common ancestor but does not include all the descendants of that ancestor) Proposed Supergroups of Eukaryotes Brown Algae Brown pigments absorb wavelengths of light that reach deeper into the

water. Largest multicellular algae Sargassum kelp Sargasso Sea

Algae parts Oomycotes (egg fungi) Saprobe (absorb food) parasites & decomposers

Lost chloroplasts Rusts water molds Chlorophyta

Green algae (chlorophyll) Most similar to plants Unicellular Desmids Multicellularfilamentous algae & volvox Complex life cycles Red Algae

Red pigments absorb wavelengths of light even deeper in the water. (green & blue) phycobilins Used to make thickeners & agar Multicellular Complex life cycles

amoebozoans Complex life cycles Closest to Animals and Fungi All have pseudopods Free-living Amoeba, slime molds, & parasites Free-living & Slime molds important

decomposers Plasmodial Slime mold Cellular Slime Molds cAMP