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Unformatted text preview: Anaerobic World (4.6 BYA) OXYGEN REVOLUTION OXYGEN REVOLUTION Anaerobic Heterotrophic Bacteria Fermentation Anaerobic Photosynthetic Bacteria One Photosystem Aerobic Photosynthesis (Bluegreen “Algae”) 3.5 BYA Two Photosystems & O2 released Aerobic World (<2.5 BYA) Krebs Cycle evolved, ozone layer developed, land could be occupied Eukaryotes Evolved No oxygen in the atmosphere; No ozone layer, UV radiation bombards earth Organic Soup (don’t understand it) Origin of Life No ozone layer (UV rays pounding) PROTISTA PROTISTA
The first Eukaryotes Problems for Protista Problems for Protista Who are the Protista? Where did they come from? How did their structures evolve? How did sex evolve? How did mitosis evolve? How did meiosis evolve? Who are the Protista? Who are the Protista? Eukaryotic (= true nucleus) Membrane bound organelles Usually single celled Mostly asexual reproduction Who are the Protista? Who are the Protista? Three major groups 1) Animallike Protista = Protozoa (Lack chloroplasts; classified by locomotion; heterotrophic) 2) Fungallike Protista (Lack chloroplasts; produce spores; heterotrophic)
1) Plantlike Protista = Unicellular algae Animallike Protista Animallike Protista Protozoa Four major groups 1) Flagellates (move with flagella) 2) Ciliates (move with cilia) 3) Amoebae (move with pseudopods) 4) Sporozoa (lack movement, produce spores) ANIMALLIKE PROTISTA ANIMALLIKE PROTISTA Protozoa Which characteristic would you expect the Protozoa to lack? 1) Ribosomes 2) Cell wall 3) Mitochondria 4) Heterotrophic nutrition 5) Nuclear membrane 6) They would have all of the above Flagellates= move with flagella Flagellates= move with flagella Zooflagellates The 9+2 structure of Eukaryotic The 9+2 structure of Eukaryotic flagella & cilia Clicker Question Clicker Question A) B) When we consider the evolution of the Eukaryotic flagellum, does it seem likely that the bacterial flagellum was its ancestral structure? Or are these analogous structures? Analogous Homologous Be sure that you have a reason for your choice. Ciliates= move with cilia Ciliates= move with cilia Must be closely related to zooflagellates Ciliates Ciliates Ciliates appear more complex than flagellates for they have elaborate organelles Amoebae= move with pseudopods Amoebae= move with pseudopods Amoebae Naked species (= without shells) Amoebae= move with pseudopods Amoebae= move with pseudopods Amoebae in silicon shells Radiolarians Amoebae= move with pseudopods Amoebae= move with pseudopods Amoebae in calcium carbonate shells Foraminiferans Slime Molds Slime Molds Protista with Fungallike Characteristics Slime Molds Slime Molds Protista with Fungallike Characteristics Cellular Slime Mold Cellular Slime Mold
Note: Amoebae Could Slime molds be related to amoebae? How are the Protozoa related to How are the Protozoa related to multicellular animals? Choanoflagellates How are the Protozoa related to How are the Protozoa related to multicellular animals? Choanoflagellates = collar cells How are the Protozoa related to How are the Protozoa related to multicellular animals? Eumetazoa
“True Animals” Parazoa Sponges Choanoflagellates Summary of Protozoan Summary of Protozoan Relationships Metazoa Parazoa
Slime Molds Choanoflagellates Foraminiferans Radiolarian s Ciliates Amoebae Zooflagellates Where Do Algae Fit In? Where Do Algae Fit In? Zooflagellates Photoflagellates Ancestral flagellates Since both protozoa &algae have flagella
Chloroplast s Let’s Look at Phytoflagellates Let’s Look at Phytoflagellates What characteristics would you NOT expect to find in singlecelled algae? 1) Mitochondria 2) Ribosomes 3) Linear chromosomes 4) Chloroplasts 5) 9 + 2 flagella 6) I would expect all of the above Major groups: Classified largely by chlorophylls 1) Dinoflagellates Ch a & c Red Tides Phytoflagellates =singlecelled algae Phytoflagellates =singlecelled algae Phytoflagellates =singlecelled algae Phytoflagellates =singlecelled algae
2. Diatoms Ch a & c silicon shells Most of the oceans’ photosynthesis occurs by diatoms Phytoflagellates =singlecelled algae Phytoflagellates =singlecelled algae
3. Euglenas Ch a & b Many heterotrophs Multicellular Algae Multicellular Algae Where do they fit in? Red Algae (Ch a & d) Brown Algae (Ch a & c) Green Algae (Ch a & b) Summary of Algae Relationships Summary of Algae Relationships a ofl Din Eu gl en g e lat el D ia ms to
B ae lg A n w ro as s Green Algae Red Algae Ch a & c Ch a & b ancestors ancestors Phytoflagellates Where Did Eukaryotes Come From? Where Did Eukaryotes Come From? Answer: They evolved from Prokaryotes Two Hypotheses: 1) Infolding hypothesis 2) Endosymbiotic hypothesis Endosymbiotic Hypothesis Endosymbiotic Hypothesis Fungi & Animals Algae & Plants Evidence for Endosymbiotic Hypothesis of Evidence for Endosymbiotic Hypothesis of the origin of mitochondria & chloroplasts
Similarities between bacteria & mitochondria & chloroplasts: 1) Binary fission 2) Size 3) Single circular naked DNA 4) Same sized ribosomes (small) 5) Protein synthesis inhibited by antibiotics 6) Enzymes for synthesis of DNA, RNA, Protein similar 7) Electron transport system in the walls of the structure 8) Experiment: Chloroplast ribosomes + bacterial ribosomes hybrid ribosome functions normally. Evidence for Endosymbiotic Hypothesis Evidence for Endosymbiotic Hypothesis
9. Mutualism is very common in bacteria & Protista: e.g. Protozoan in termite guts Mixotricha paradoxa Clicker Question Clicker Question A) B) C) D) E) Malaria parasites are protozoans that live in red blood cells of humans. How many cell membranes would an oxygen molecule from the RBC have to pass through in order to reach the center of a malaria parasite’s mitochondrion? One Two Three Four Five Evidence that Archaebacteria was Evidence that Archaebacteria was the host cell forming eukaryotes Most eukaryotic genes for replication, transcription, & translation are related to Archaebacteria forms not Eubacteria forms But biosynthetic & metabolic functions of eukaryotes are related to Eubacteria forms TODAY’S VIEW Bacteria gave rise to mitochondria & chloroplasts ( & flagella ?) Archaebacteria gave rise to basic gene function. Infolding of the cell membranes lead to the formation of the nucleus, endoplasmic reticulum, Golgi, lysosomes. But did the infolding occur before the mitochondria entered into the host cell or after ? ...
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