Transcript Protists
Protists Section 18-1 Kingdom Protista Eukaryotic – 200,000 species No simple set of common characteristics Can be unicellular or multicellular Microscopic or very large Aerobic or anaerobic Autotrophic or heterotrophic Sexual or asexual reproduction Evolution of Protists About 2 bya, prokaryotes began to grow larger and develop internal membranes, like the nuclear membrane Then evolved organelles to help with complex functions like the GA and ER Endosymbiont hypothesis explains the evolution of the mitochondrion and the chloroplast Sexual Reproduction Evolves First appeared about 300 million years after the first protists Allowed for rapid evolution because of the increased genetic variation Eukaryotes experienced a huge adaptive radiation, leading eventually to the billions of eukaryotes we have today Classifying Kingdom Protista Anything eukaryotic that cannot be classified as a fungus, plant, or animal is put into Kingdom Protista Further classified by the organisms they most resemble: Plant-like protists Animal-like protists Fungus-like protists Plant-Like Protists AKA algae Photosynthetic autotrophs that contain chlorophyll About 30,000 different species Perform 30-40% of all photosynthesis Can be unicellular or multicellular Plant-Like Protists Red Tide Animal-Like Protists AKA protozoans, first-animals Start out unicellular, but some gather together to live in community at some point in their life cycle Four phyla, classified by how they move Flagellates Called flagellates, because they move using flagella Giardia Sarcodines Have pseudopods (false-feet) Amoeba Amoeba Ciliates Have cilia, tiny hairlike structures for movement Paramecium Paramecium Phylum Sporozoa Called sporozoans Parasitic, produce spores Plasmodium falciparum Fungus-Like Protists Lack chlorophyll, absorb food through their cell walls Called slime molds Life Cycles of Protists Varied life cycles Euglenophytes branched off before sexual reproduction and therefore only reproduce asexually Only genetic variation is from mutation Reproduction in Algae Alternates between sexual and asexual reproduction, as do green plants Called alternation of generations Diploid (2n) and haploid (n) cells switch back and forth Reproduction in Algae Diploid generation called sporophyte because it undergoes meiosis to produce haploid spores Spores grow into haploid male and female cells called gametophytes Gametophytes produce egg and sperm, which fuse to form zygote Zygote develops into sporophyte Alternation of Generations Sporophyte Gametophyte Reproduction in Protozoans Sarcodines (like Amoeba) reproduce asexually by binary fission Sporozoans produce spores, which are reproductive cells formed without fertilization that can produce a new organism Reproduction in Fungus-Like Protists Cellular slime molds spend most of their lives as individual, free-moving amoebalike cells Under certain circumstances, they gather into a sluglike mass, which then forms a fruiting body Fruiting body releases spores, which will develop into free-moving cells