BIOL 172 3 Protists II.pdf

Protists II BIOL 172  Diplomonads Excavata Parabasalids Euglenozo...

Protists II BIOL 172  Diplomonads Excavata Parabasalids Euglenozoans Stramenopiles Diatoms Golden algae Brown algae “SAR” clade Dinoflagellates Alveolates Apicomplexans Ciliates One current phylogeny Forams splits all eukaryotes into Rhizarians Cercozoans four “supergroups” Radiolarians Archaeplastida Red algae Chlorophytes Green algae Charophytes Land plants Amoebozoans Slime molds Tubulinids Entamoebas Unikonta Nucleariids Opisthokonts Fungi Choanoflagellates Animals  Alveolates Members of the group Alveolata have membrane- bounded sacs (alveoli) just under the cell membrane. They include dinoflagellates, apicomplexans, and ciliates. Flagellum Alveoli Alveolate  Dinoflagellates Dinoflagellates have two flagella and each cell is reinforced by cellulose plates (cellulose is the main structural molecule in plants, so this is a case of convergent evolution). They are abundant components of both marine and freshwater plankton and can be autotrophs, heterotrophs or mixotrophs. Flagella http://vimeo.com/28059785 Some dinoflagellates release a powerful, short-lived toxin in the presence of large fish schools and can cause “red tide”. https://www.washingtonpost.com/news/speaking-of-science/wp/2018/08/03/a-red- tide-ravaging-florida-may-have-killed-a-whale-shark-for-the-first-known-time/  Apicomplexans Apicomplexans are specialized parasites of animals, and some cause serious human diseases. Most have sexual and asexual stages that require two or more different host species for completion.  Apicomplexans Apicomplexans spread through their host as infectious cells called sporozoites. One end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues. Apical complex Red blood cell Two of the most common are Plasmodium and Toxoplasma Four species of Plasmodium cause malaria in humans (many species in other animals) and are transmitted through infected blood carried by Anopheles mosquitoes. Over 40 percent of the world’s population lives in contact with malaria and there are about 200 million cases each year.  Inside human Merozoite A sporozoite form is transmitted from the Liver mosquito to a person’s blood. Liver cell A merozoite form reproduces in the liver Apex and then infects red Red blood Merozoite blood cells. (n) cell Red blood A feeding form cells consumes the hemoglobin of blood cells. Rupture of cells leads to symptoms of chills Gametocytes Key (n) and fever. Haploid (n) Diploid (2n)  Inside mosquito Inside human Merozoite Liver Sexual reproduction Liver cell occurs in mosquitoes that consume infected human blood. Apex Red blood Merozoite cell (n) Zygote Red blood (2n) cells FERTILIZATION Gametes Gametocytes Key (n) Haploid (n) Diploid (2n)  Inside mosquito Inside human Merozoite Sporozoites (n) Liver Liver cell Oocyst Apex MEIOSIS Red blood Merozoite cell (n) Zygote Red blood (2n) cells FERTILIZATION Gametes Gametocytes Key (n) Haploid (n) Diploid (2n) Most endemic Hawaiian birds have gone extinct, in large part due to avian malaria following introduction of mosquitoes in the 1800’s. Asexual reproduction Sexual reproduction in in birds, or mammals cats (primary host). (including humans.) Toxoplasma gondii forms cysts in the brains of hosts. Although infection does not usually cause disease it can have affects on the host’s behavior. Infected rats are more active, less fearful, and even attracted to the scent of cats, symptoms that would increase transmission to the primary host. Studies also suggest behavioral changes due to infection in humans.  Ciliates Ciliates, a large varied group of protists, are named for their use of cilia to move and feed. Ciliates include the well-known Paramecium.  Ciliates They have large macronuclei and small micronuclei. Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei. Conjugation is a sexual process, a process that shuffles genetic code, and is separate from reproduction, which occurs by binary fission, a simple splitting of one cell into two. Compatible mates MEIOSIS Haploid Diploid micronucleus micronucleus The original Diploid macronucleus micronucleus disintegrates. MICRONUCLEAR FUSION Key Conjugation Asexual reproduction  Stramenopiles The clade Stramenopila includes important autotrophs as well as some heterotrophs. Most have one “hairy” and one “smooth” flagellum. Hairy flagellum Smooth flagellum These includes diatoms, golden algae, brown algae. Diatoms are unicellular algae with a unique two-part, glass-like wall of hydrated silica. Diatoms reproduce asexually and occasionally sexually. Diatoms are a major component of phytoplankton and fossilized diatom walls compose much of the sediments known as diatomaceous earth. Brown algae are the largest and most complex algae and include the “seaweeds” or kelp. All are multicellular, and most are marine. Note that “algae” is not a good taxonomic term. It is loosely applied to many different photosynthetic aquatic and marine organisms, both prokaryotic and eukaryotic. Blade Stipe Holdfast  Diplomonads Excavata Parabasalids Euglenozoans Stramenopiles Diatoms Golden algae Brown algae “SAR” clade Dinoflagellates Alveolates Apicomplexans Ciliates Forams Rhizarians Cercozoans Radiolarians Archaeplastida Red algae Chlorophytes Green algae Charophytes Land plants Amoebozoans Slime molds Tubulinids Entamoebas Unikonta The supergroup Unikonta Nucleariids Opisthokonts Fungi includes animals, fungi, Choanoflagellates and some protists Animals  Amoebozoans Amoebozoans are amoeba that have lobe- or tube-shaped pseudopodia (foot-like extensions). They include single-celled, free living and parasitic amoeba as well as colonial slime molds. Plasmodial slime molds are amoeba “supercells” containing many nuclei that inhabit moist soil or decaying vegetation and feed by phagocytosis (cell-feeding, engulfing and drawing within).  FERTILIZATION Zygote Feeding (2n) plasmodium Mature plasmodium (preparing to fruit) Young Amoeboid cells sporangium Flagellated (n) cells (n) Mature Germinating sporangium spore Spores (n) MEIOSIS Life cycle of a Key Stalk Haploid (n) plasmodial slime mold Diploid (2n) http://www.youtube.com/watch?v=B79Z56vl02A Cellular slime molds are microscopic amoeba that feed as individual cells but can form multicellular aggregates to migrate as a visible mass and disperse reproductive spores. Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity  Spores FERTILIZATION (n) Emerging amoeba (n) Zygote SEXUAL (2n) Solitary REPRODUCTION 600 m amoebas (n) MEIOSIS Amoebas (n) Fruiting ASEXUAL bodies REPRODUCTION (n) Aggregated amoebas Migrating aggregate 200 m Key Haploid (n) Diploid (2n)