Stramenopiles, red algae, green algae and amoeboids

STRAMENOPILES All have numerous fine, hair-like projections on the flagellae. Photosynthetic organisms have chloroplasts housed within a double membrane with cytoplasm + ‘nucleus’ Diatoms Golden algae Brown algae Water moulds

Diatoms Diatoms have a siliceous case like a Petri-dish Some rocks are formed almost entirely of fossil diatoms (diatomite or diatomaceous earth). These deposits are mined commercially as abrasives and for filtering.

Golden Algae golden algae are common in fresh water. Some species are colorless, but the vast majority are photosynthetic. They are particularly important in lakes, where they may be the primary source of food for zooplankton. They are named for their yellow and brown carotene and Xanthophyll accessory pigments.

Brown Algae The largest and most complex algae Eaten as a human food Used as fertiliser Produce agar, a gelling agent

Water Moulds Cellulose cell wall Diploid nuclei Free-swimming spores bear two dissimilar flagella, one with fine, hair-like projections Important pathogens root rotting fungi, seedling dampening mould, blister rusts, white rusts downy mildews Phytophthora infestans - late blight

RHODOPHYTA - the Red Algae No flagellated stages in the life cycle. Phycoerthyrin gives the red colour Larger specimens are eaten (Dilisk = Porphyra)

Green algae The most ‘plant-like’ of all ‘protists’ with cellulose cell walls, chlorophylls a and b, carotene accessory pigments, alternation of generation. Charaphytes are particularly close Vary from unicells to complex multicellular structures

Alternation of generation A life cycle where there is both a multicellular haploid (gametophyte) and diploid (sporophyte) phase to the life cycle Diploid sporophyte 2N Fusion Meiosis Spores N Gametes Haploid gametophyte

Amoeboid protists Slime moulds

Slime moulds Long classified as part of the Fungi, slime "molds" are now known to be quite unrelated to the fungi. When conditions become unfavorable, these slime molds aggregate together and form sporangia often on the tips of stalks There are three groups of slime molds. Cellular Acellular Slime nets (now put into the Stramenopiles)

Cellular slime moulds Cellular slime molds (e.g. Dictyostelium) spend most of their lives as separate single-celled amoeboid protists, but upon the release of a chemical signal, the individual cells aggregate into a great swarm. Haploid

Haplontic life cycle A life cycle where there is only a multicellular haploid (gametophyte) phase to the live cycle Immediate spore production 2N Fusion Meiosis Spores N Gametes Haploid gametophyte

Acellular slime moulds Plasmodial slime molds, like Physarum shown here, are basically enormous single cells with thousands of nuclei (coenocytic). Diploid

Diplontic life cycle A life cycle where there is only a multicellular diploid (sporophyte) phase to the live cycle and the haploid (gametophyte) phase is unicellular Diploid sporophyte 2N Fusion Meiosis N Gametes

Amoeboids Form pseudopodia to engulf their prey 3 subgroups Rhizopods / Amoebas - flowing cytoplasm Actinopods (Heliozoans and Radiolarians) - slender pseudopodia Foraminiferans - calcareous shells

Entamoeba histolytica (amoebiasis/amoebic dysentery) Humans are infected by ingesting cysts, most often via food or water contaminated with human fecal material

Actinopods Have slender, flexible pseudopodia extruded through the cell wall.

Foramenifera Stiff pseudopodia extruded through the cell wall. Can form sybioses with photosynthetic protists.