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Figure 20.UN01 Which of these trees is not like the others….. (a) A B D B D C C C B D A A (b) (c) Figure 24.18 Euryarchaeotes Crenarchaeotes UNIVERSAL ANCESTOR Nanoarchaeotes Proteobacteria Bacteria Spirochetes Cyanobacteria Gram-positive bacteria Domain Bacteria Chlamydias Prokaryotes Archaea Domain Archaea Korarchaeotes Domain Eukarya Eukaryotes Who are the Eukaryotes? How do they get their energy? Which lineages are good monophyletic groups? When did they evolve? GO back to your timeline…. Fossils 1.8bya (but lipids made by Euk. around 2.7 bya) Multicellularity? 600mya Protists-ARE ONE type of Eukaryote! DIVERSITY Many are important ocean photosynthesizers! p500 Parasitic protists • Trichomonas • Giardia- beavers • Malaria p501 Figure 20.20 Euglenozoans Forams Diatoms Red algae Green algae Land plants Domain Eukarya Ciliates Amoebas Fungi Animals Methanogens COMMON ANCESTOR OF ALL LIFE Thermophiles Domain Archaea Nanoarchaeotes Proteobacteria Chlamydias Spirochetes Gram-positive bacteria Cyanobacteria (Chloroplasts)* Domain Bacteria (Mitochondria)* Eukaryotes have a Nucleus ORIGIN OF THE NUCLEAR ENVELOPE 1. Ancestor of the eukaryotes. Chromosomes Where did it come from? Plasma membrane 2. Infoldings of plasma membrane surround the chromosomes. 3. Eukaryotic cell. Nucleus Endoplasmic reticulum Eukaryotes also have mitochondria and chloroplasts-Endosymbiosis! Lynn Margulis Figure 25.3 Cytoplasm DNA Ancestral prokaryote Plasma membrane Endoplasmic reticulum Engulfing of aerobic bacterium Engulfing of photosynthetic bacterium Nucleus Nuclear envelope Mitochondrion Mitochondrion Ancestral heterotrophic eukaryote Plastid Ancestral photosynthetic eukaryote Figure 25.3 Cytoplasm DNA Ancestral prokaryote Plasma membrane Endoplasmic reticulum Engulfing of aerobic bacterium Engulfing of photosynthetic bacterium Nucleus Nuclear envelope Mitochondrion Mitochondrion Ancestral heterotrophic eukaryote Plastid Ancestral photosynthetic eukaryote Figure 20.21 populations Methanogens Thermophiles Cyanobacteria Proteobacteria Domain Bacteria HOW? Domain Archaea So sometimes whole organisms were engulfed-but genes were also being swapped Ancestral cell Plantae Domain Eukarya How do we show endosymbiosis on a phylogenetic tree? Figure 29-16 Engulfing of a protist that already engulfed a photosynthetic prokaryote SECONDARY ENDOSYMBIOSIS Predatory protist Photosynthetic protist Nucleus Chloroplast Nucleus 1. Photosynthetic protist is engulfed. Some ate a green algae and some ate a red algae. 2. Nucleus from photosynthetic protist is lost. Organelle with four membranes 1 2 3 4 Figure 25.4 Cyanobacterium Membranes are represented as dark lines in the cell. Primary endosymbiosis Secondary endosymbiosis Red alga Dinoflagellates Plastid 1 23 Stramenopiles Secondary endosymbiosis Nucleus Heterotrophic One of these eukaryote membranes was lost in red and green algal descendants. Secondary endosymbiosis Plastid Euglenids Green alga Chlorarachniophytes Figure 25.5 Many protists are multicellular! This is a colonial protist with rigid cell wallswhat do we mean by colonial? When did multicellularity evolve? What traits would need to evolve in order to be a multicellular organism? What would you have to be able to do? More on multicellularity… integration! •Stick together •Communicate •Ways of moving materials around •Germ vs Soma-controls on mitosis and meiosis •Differentiated cells are arranged in tissues •Genes regulated so that even though all cells contain all the animals genes, particular genes are active only in particular cells at certain times during a lifetime •These things require changes in controls over developmental processes and changes in gene expression rather than new cellular structures or genes not present in unicellular organisms! Multicellularity evolved many times Ex Algae (“protists”), Plants, Fungi and Animals Figure 25.6 Flagellum Cytoplasm Chlamydomonas Outer cell wall Inner cell wall Gonium Few totally new genes….. Pandorina Outer cell wall Cytoplasm Volvox Extracellular matrix (ECM) Figure 25.7 What do we know? Multicellularity in animals… Individual choanoflagellate Choanoflagellates OTHER EUKARYOTES Sponges Animals Collar cell (choanocyte) Other animals Figure 32-11a Choanoflagellates are sessile protists; some are colonial. Colony Choanoflagellate cell Food particles Water current Genome of a single celled choanoflagellate vs animals Many protein domains in common (domain is a key part or functional region of a protein) Choanoflagellate had the same domains that in animals are important in cell adhesion and signaling. So evolution of multicellularity involved the “coopting” of existing genes that had been used for other purposes As well as one small new piece the CCD domain in the cadherin protein Figure 25.8 Choanoflagellate Hydra Fruit fly Mouse “CCD” domain Text goes over taxonomy of protists…which we will skip. And then text goes over functional importance.. Protists-ARE ONE type of Eukaryote! DIVERSITY Many are important ocean photosynthesizers! p500 Parasitic protists • Trichomonas • Giardia- beavers • Malaria p501 Development is obviously only important in multicellular organisms How do we get such diversity of morphology? Small changes in development can yield big differences in shape or morphology. See P 449-CH23 Two kinds of developmental changes 1. Homeotic mutations affect placement and number of body parts (typically Hox mutations) Numbers of legs Expression of a particular Hox gene suppresses the formation of legs in fruit flies (and presumably all insects) but not brine shrimp (Pinpointed the exact amino acid changes) Hox gene 6 Hox gene 7 Hox gene 8 Ubx About 400 mya Drosophila Artemia What is going on here? 2. Heterochronic (allometric) changes or mutations These affect the timing or rate of development of different body parts (rate of mitosis) parts pulled and stretched at different rates to make “new” morphologies… Figure 23.16 Chimpanzee infant Chimpanzee adult Chimpanzee fetus Chimpanzee adult Human fetus Human adult Heterochrony…paedomorphosis..Some species of salamander retain juvenile characteristics (external gills) into sexual maturity Sticklebacks-Ex from text… Lakes with predators-make spines No predators-no spines What is genetic basis of this evolutionary change? Change in nucleotide sequence OR change in how the gene is expressed or regulated Thoughts on which is more risky?? Easier?? Change in way gene is regulated… Pleiotropic effects of gene can be controlled (turn off spine production but other functions of gene on other parts of body retained)