BIOL 112 1st Edition Lecture 12 Outline of Last Lecture I Heterotrophy II Systematics Taxonomy III Three Domains IV Domain Archaea V Domain Bacteria VI Recent Historical Trends VII Distinguishing Characteristics of Eukarya VIII Endosymbiont Theory IX Sequence of Endosymbiotic Events Outline of Current Lecture X Chloroplasts A Second Endosymbiosis XI Modern Protistans XII Traditional Groupings XIII General Eukaryotic Life Cycle XIV Terms XV Domain Eukarya XVI Supergroup Excavata XVII Alveolata XVIII Apicomplexans XIX Stamenopila XX Oomycota These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XXI Supergroup Archaeplastida XXII Animals XXIII Body Plan Criteria for Organizing Animals XXIV Digestive System Current Lecture I Chloroplasts A Second Endosymbiosis Molecular homologies link most chloroplast genomes most closely to cyanobacteria blue green algae This could mean that most modern chloroplasts arose from one original cyanobacterial like ancestor or that several times with closelyrelated cyanobacteria Closest candidate for chloroplast ancestor is called Prochlorothrix an aerobic cyanobacteria with both chlorophyll a and b Combination of alga and cell now could do Hill Reaction and Calvin Cycle As with mitochondria over time symbiont genes were progressively transferred into host cell genome so that modern chloroplast genome is minimal An additional feature of this model is the hypothesis that some eukaryotic algae could become symbionts themselves with other eukaryotic hosts Secondary Endosymbiosis Symbiont loses all but its chloroplast function and its plasma membrane over time because all other functions are duplicated by host Detectable because chloroplasts are surrounded by extra membranes II Modern Protistans Systematics are constantly changing No universally agreed system of number of kingdoms or number of phyla or bases of defining criteria Revisions debates drain by mass of new data especially molecular sequence information These lectures are based on Campbell s scheme but be aware of the tentative nature of this III Traditional Groupings Used to be sub Kingdoms but not anymore One approach informal groupings Animal like Protists protozoa Plant like Protists algae Fungus like Protists slime molds These categories defined general lifestyle and nutrition characteristics Representatives in each group might resemble forms ancestral to the 3 major multicellular kingdoms IV General Eukaryotic Life Cycle Alternation between haploid and diploid phases of life cycle with sexual events meiosis and fertilization between phases The X scheme Diploid Phase 2n sporophyte phase of meiosis and spore formation Haploid Phase n gametophyte phase of gamete formation for fertilization Some species emphasize one phase over the other others have extended periods of existence in both phases i e haploid or diploid dominant and the other reduced V Terms If haploid and diploid phases look identical then this is an isomorphic generation species If haploid and diploid phase organisms look very different from one another then this is a heteromorphic generation species Types of gametes also differ Isogamy Both gametes are same size and appearance both frequently motile considered a primitive condition Anisogamy One gamete larger than the other both still motile Oogamy One gamete huge non motile egg the other small and motile sperm VI Domain Eukarya All the eukaryotes protistan Kingdoms and the three crown group Kingdoms 11 or more Kingdoms in the tentative scheme in Campbell Defined distinguished by molecular sequence divergence homology especially for rDNA sequences and also some phenotypic characters Some have more than one phylum others only one phylum per kingdom Some groups not yet considered or organized VII Supergroup Excavata Possibly three kingdoms Diplomonads Parabasilids Euglenozoans Originally diplomonads thought to have been pre mitochondrial eukaryotes Now shown to have mitochondrial genes so they must have lost mitochondria instead Nevertheless very primitive forms symbiotic mostly parasitic no mitochondria poorly Diplomonads Giardia lamblia hiker s diarrhea Parabasalids Trichomonas vaginalis human female infection hypermastigids termite gut symbionts eat and digest wood for insect Euglenozoans Euglena VIII Alveolata All members possess alveoli fluid filled sacs just under the plasma membrane function unknown Also unified by molecular homologies of rDNA sequences Three phyla Dinoflagellates Apicomplexans Sporozoa Ciliates IX Apicomplexans Also known as Sporozoans all parasitic many with complex life cycles common forms All members have characteristic apical complex Function might help parasite cell attach to and invade host cell Life cycles are very complex because they frequently involve two or three different host organisms Commonly alternate between invertebrate insect crustacean etc and vertebrate hosts and sexual invertebrate host and asexual vertebrate host phases Ex malaria toxoplasma X Stamenopila Defined by possession of hair like projections on flagella stramenopiles Four phyla in kingdom Oomycota water molds rusts mildews Diatoms walls made of silica Golden Algae Brown Algae Kelps Water molds are strictly heterotrophic many parasitic Other groups are photosynthetic XI Oomycota Water Molds mildews Superficially similar to fungi mycelia spores heterotrophic decomposer nutrition But significant differences cellulose cell walls flagellated zoospores diploid dominant life cycle as well as molecular differences Fluffy masses on dead or diseased tissues Some species parasitic Phytophthora infestans cause of Irish Potato Blight that started Potato Famine disruption of Irish culture in 1840s XII Supergroup Archaeplastida Rhodophytes and Green Algae Possibly ancestral to K Plantae Unified by details of chloroplast structure and genomic content Includes Carophyceans advanced algae possible immediate ancestors to plants K Rhodophyta Red algae Red color from accessory pigment phycoerythrin Lack any flagellated stage in life cycle Gametes must rely on water currents to find each other Some species can live at great ocean depths 260 m in very dim light because of additional pigments permit high efficiency light harvesting Harvested for cell wall extracts carageenin and agar K Chlorophyta Green Algae Seaweeds Ancestral to plants Extremely similar chloroplast structure and pigment content