Protists and fungi Chapters 19 and 20
Origin of Eukaryotic Cells • Endosymbiotic Theory • The eukaryotic cell probably originated as a community of prokaryotes 2 billion years ago. • The nucleus and endomembrane system of organelles probably evolved from infoldings of the plasma membrane of ancestral prokaryotes. • Mitochondria and chloroplasts probably evolved from symbiotic prokaryotes that took up residence inside larger prokaryotic cells.
Connection to Evolution If prokaryotes were the first cells, how did eukaryotes evolve?
Plasma membrane Endoplasmic reticulum Nucleus Cytoplasm Nuclearenvelope Ancestral prokaryote Cell with nucleus and endomembrane system Aerobic heterotrophicprokaryote Mitochondrion Mitochondrion Photosyntheticprokaryote Chloroplast Somecells Ancestral host cell Photosyntheticeukaryotic cell
DOMAIN EUKARYA KINGDOM PROTISTA
Domain Eukarya Kingdom Protista • Characteristics of a Protist: • Often characterized by what they are NOT • Not animals, plants, or fungi • Diverse group of 200,000 organisms • Cell type: EUKARYOTES • Mode of Nutrition: Heterotrophs and autotrophs • Habitat: water or moist soil; some live in animals causing disease
Categorizing Protists • Animal-like (Protozoans) • Plantlike (Algae) • Fungus-like (Slime mold & mildew)
Protozoa • Animal-like heterotrophs • Four Phlya: • Phylum Ciliophora: Use cilia for motion • Phylum Sarcodina: Use pseudopods for motion • Phylum Apicomplexa: Use spores for motion • Phylum Zoomastigina: Use flagella for motion
Kingdom Protista Phylum Ciliophora • AKA: Ciliates • Use short, hair-like projections to move through fluids and move food particles into the cell • 7000 species of ciliates • Abundant in oceans, lakes, and rivers • Example: Paramecium caudatum
Kingdom Protista Phylum Sarcodina • Animal-like protists that use pseudopods for feeding and locomotion • Pseudopod: false foot; a temporary extension of cytoplasm that surrounds and envelops smaller organisms, forming a food vacuole • Example: Amoeba
Kingdom Protista Phylum Apicomplexa • AKA: Sporozoans • Produce spores (reproductive cells) during their life cycle • Parasitic and move as their hosts move • Hosts transmit the spores to new hosts • Example: Plasmodium (malaria)
Kingdom Protista Phylum Zoomastigina • AKA: Zooflagellates • Use flagella to move • Cause American and African sleeping sicknesses • Example: Trypanosoma • Infects a tsetse fly which transmits disease to humans
Algae • Plant-like protists because they contain photosynthetic pigments • Found in bodies of water • Can be unicellular or multicellular • Unicellular Phyla: • Phylum Bacillariophyta: Diatoms • Phylum Pyrrophyta: Dinoflagellates • Phylum Euglenophyta: Euglenoids • Phylum Chrysophyta: Chrysophytes (colonies) • Multicellular Phyla: • Phylum Phaeophyta: Brown Algae • Phylum Chlorophyta: Green Algae • Phylum Rhodophyta: Red Algae
Kingdom Protista Plant-like Examples • Diatoms • Unicellular • Photosynthetic autotrophs using chlorophyll (green pigment) and carotenoids (golden pigment) • Store food as oil, which is less dense that water • Float near the surface of water where they can absorb energy from the Sun for photosynthesis
Kingdom Protista Plant-like Examples • Dinoflagellates • Unicellular • Have two flagella at right angles to one another • Cause the organism to spin as they move through the water • Some are photosynthetic autotrophs and others are heterotrophs • Some use red pigment for photosynthesis, which cause red tides during blooms • Produce dangerous toxins
Kingdom Protista Plant-like Examples • Green Algae • Unicellular and multicellular • Use chlorophyll for photosynthesis • Have cell walls and store food as carbohydrates • Most are found in freshwater
Kingdom Protista Fungus-Like Examples • AKA: Slime molds • Similar to fungus: • Use spores to reproduce • Feed on decaying organic matter and absorb nutrients through their cell walls • Different from fungus: • Fungi cell walls contain chitin, a complex carbohydrate. • Slime mold cell walls contain cellulose.
Connection to Evolution Protists are mainly unicellular. How did multicellular organisms evolve?
Evolution of Multicellular Organisms • Multicellular organisms probably evolved from colonial protist cells becoming specialized • Multicellular life has diversified over hundreds of millions of years Gamete Locomotorcells 1 2 3 Somaticcells Food-synthesizingcells Unicellularprotist Colony Early multicellular organism withspecialized, interdependent cells Later organism thatproduces gametes
Evolution of Multicellular Organisms • Multicellular life first arose over a billion years ago • All life was aquatic until almost 500 million years ago Multicellular organismscolonize land PALEOZOICERA Diverse multicellular algae, fungi,and animals, all living in the sea Mass extinctions Earliest animals; manymulticellular algae Age of fossils in millions of years Oldest known fossils ofmulticellular eukaryotes(small algae) PRECAMBRIAN ERA Earliest multicellular eukaryotes?
DOMAIN EUKARYA KINGDOM FUNGI
Characteristics of Fungi • Diverse– over 100,000 species have been identified • Some are mutualistic organisms • Others are parasites • Some are predators • Others are decomposers of dead organisms
Characteristics of Fungi • Type of cell: eukaryote • Mode of nutrition: heterotroph • Number of cells: • Most are multicellular • Yeasts are unicellular • Cell structure: cell wall composed of chitin
Unique Fungi Characteristics • Hyphae: long chains of cells; threadlike filaments that make up the body of the fungus • Mycelium: netlike mass of hyphae; sometimes underground • Fruiting body: fungus seen above ground; example-mushroom
Nutrition in Fungus • All fungi are heterotrophs, but there are three types of fungi that differ in how they obtain nutrients. • Saprophytic fungi: DECOMPOSER • Feed on dead organisms or organic wastes • Return nutrients to the food chain • Parasitic fungi: absorb nutrients from the living cells of a host organism • Mutualistic fungi: WORK TOGETHER • Example: Soybean root fungus receives sugar from the soybean root and helps the root to increase water and mineral uptake.
Phyla of Fungi Chytrids are closely related to protists. The are unicellular. Earliest fungi. Common molds are multicelluar and composed of stolons on the surface and rhizoids that penetrate the surface. Club fungi are the most commonly recognized fungus. They are multicellular. Yeast is unicellular, but most members are multicellular. 1 2 3 4
Ecology of Fungi • Lichens consist of fungi living mutualistically with photosynthetic organisms. • Lichens are associations of algae or cyanobacteria with a network of fungal hyphae. • The fungus receives food in exchange for housing, water, and minerals. • Lichen serve as bioindicators or environmental changes.
Parasitic Fungi • Parasitic fungi cause disease • Dutch elm disease • Corn smut • Athlete’s foot
Beneficial Fungi • Numerous fungi are beneficial • Many are important in the decomposition of organic material and nutrient recycling • Fungi are also important as food • Mushrooms are the fruiting bodies of subterranean fungi • Yeasts (unicellular fungi) are essential for baking and beer and wine production • Fungi are used to ripen certain cheeses
Beneficial Fungi • Penicillin – First antibiotic to be discovered Staphylococcusaureus Penicillium Zone ofinhibitedgrowth