Looking Back at Bio 115 The Organism as a Unit of Life Cellular Structure (cell = unit of life)…one or many! Metabolism = Homeostasis (PSN, Resp, N 2 fix, ferment, etc.) Growth = irreversible change in size Reproduction…failure = extinction Acclimatization-short term responses = behavior Adaptation-long term responses = evolution
Shifting Kingdoms Bacteria Archaebacteria Archezoans Euglenoids Chrysophytes Green Algae Brown Algae Red algae Slime Molds True Fungi Bryophytes Tracheophytes Protozoans Myxozoans Multicellular Animals Lumpers Splitters PlantaeProtistaRhodophyta
How Many Kingdoms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaebacteria Bacteria Original Cell Extant Extinct Long Time with Prokaryotes only
Rhodophyta Photosynthetic, mostly marine red algae Odd features Body multicellular, supported by water, so simple thallus Thallus attached to substrate by holdfast Rarely pelagic (floating) Chloroplasts have three membranes (secondary endosymbiont) Photosynthetic pigments: chlorophyll a, phycoerythrin, phycocyanin…colors can be red, brown, purple, blue, green, blackish! Storage materials: floridean starch in cytosol ( -1,4-glycan) Wall polysaccharides: cellulose and agar or carrageenan No flagella, so centriole missing Gametangia: spermatangia (male) and carpogonium (female) Some species encrust with calcium carbonate…contribute to reefs 4000 species
Compsopogon Caloglossa llery/Callithamnion_baileyi_lb2306.jpg Callithamnion Porphyridium Here are some of the example red algae some of these you should have observed in laboratory.
Polysiphonia nigrescens Polysiphonia nigrescens 2N tetrasporophyte tetrasporangium tetraspore (meiospore) benthic (attached) filamentous common on New England rocky coast
Tetraspore (meiospore) germinates into isomorphic homothallic gametophyte (1N) thallus Male branches near the tops of the plants produce spermatangia Female branches near the bottom of the thallus produce carpogonia Polysiphonia nigrescens
marine/algae/polysiphonia%20male.jpg Tetraspore (meiospore) germinates into isomorphic thallus Male branches produce spermatangia releasing spermatia Polysiphonia nigrescens Female branches produce carpogonium with trichogyne. Trichogyne receives spermatium (no flagellum!) trichogyne spermatium
Polysiphonia nigrescens The 2N zygote develops inside the cystocarp attached to the gametophyte (1N) thallus. uk.net/mag/imgmar99/polys3.jpg The cystocarps expand and mature into carposporangia Carposporangia release diploid carpospores which then germinate into diploid tetrasporophytes.
carpogonium Polysiphonia Life Cycle Gametophyte isomorphic homothallic 1N2N syngamy meiosis Carposporophyte (inside cystocarp) spermatangium spermatium (released to water) trichogyne Note: See previous slides for photo credits! cystocarp zygote (inside cystocarp) carpospore (released to water settles to substrate grows by mitosis) Tetrasporophyte tetrasporangium tetraspore (released to water settles to substrate grows by mitosis) gametes (produced by mitosis) tetrasporocyte