Bio 200 Week 7 Notes
Bio 200 Week 7 Notes BIO 200LLB
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This 6 page Class Notes was uploaded by Nicole on Sunday October 18, 2015. The Class Notes belongs to BIO 200LLB at University at Buffalo taught by Lindqvist, C in Fall 2015. Since its upload, it has received 43 views. For similar materials see Evolutionary Biology in Biological Sciences at University at Buffalo.
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Date Created: 10/18/15
October 12 2015 Lecture 13 Origin of the Eukaryotes 1 Earliest eukaryotes 2 Eukaryotic Traits 3 Origin of organelles 4 Endosymbiosis Mitochondria amp chloroplasts Protists 1 Protists are not monophyletic 2 Protist Traits 3 Building the bridge to multicellularity Types of Protists 1 Alveolates 2 Stramenopiles 3 Rhizarians 4 Excavates 5 Amoebozoans 6 Choan agellates Origin of the Eukaryotes Eukaryotes arise between 27 and 17 billion years ago Have cells much larger than prokaryotes Thicker walls Internal membrane Several events preceded the origin of the eukaryotic cell Flexible cell surface Cytoskeleton Nuclear envelope Digestive vacuoles Endosymbiosis Eukaryotic Traits 1 Multicellular a Allows for exibility 2 Sexual reproduction a Leads to increased genetic diversity recombination 3 Compartmentalization a Organelles that carry out different functions in the cell b Requires several stages Evolution to eukarya Loss of the cell wall endocytosis Origin of the nucleus and ER both the result of membrane enfolding Endosymbiosis Living together in close associationquotan ancestral eukaryotic cell engulfed an aerobic energy producing bacteria but did not digest it Over time this arrangement be came permanent led to mitochondria Endosymbiotic events are examples of horizontal gene transfer Origin of Eukaryotes Began with ancestral protists some scientists refer to them as microbial eukaryotes Protists are only unified by the fact that they all have organelles Highly paraphyletic Protists bring up issues with traditional classifications Variations in Protist Traits reveal lack of Unity in the Group 1 Locomotion 2 Cell Surfaces a Some protists have extracellular material to shield them from negative aspects of the environment 3 Nutrition a Chemoautotrophyonly observed in protists photosynthesis 4 Reproduction a Both sexual and asexual protists Protists Show the Development of Multicellularity Eukaryotic cells began living in close association Associations become colonies Individuals in colony take on different roles Colony begins to function as an individual Protist Groups Archaeplastida Amoebozoa Opisthokonta Alveolates are a diverse group identified by the presence of alveoli 3 types have all developed very interesting types of nutrition Aplicomplexeansparasites with apical Dino agellates are photosynthetic amp have 2 agella one short one long within 2 grooves on their surfaces Can cause red tides during which times they 5 5 release toxins that kill birds amp other mammals Dinoflagellates A Apicomplexans Choano agellates A Ciliates lt Gymnamoebas Diplomonads Parabasalids Euglenozoans Golden algae Brown algae Radiolarians Chlorophytes green algae Charophytes green algae Land plants Slime molds Entamoebas Nucleariids tn 6 O N O o h lt1 0 Diatoms Oomycetes Forams Red algae A Fungi Animals Eukaryotic Supergroups A Alveolates Stramenopiles I Common eukaryotic ancestor Ciliatemove using cilia amp are heterotrophic http philschatzcom biologybook resources Figure2 30301jpg Stramenophila characterized by the fine hairs extending from their agella Brown Algaemulticellular include giant kelp DiatomsUnicellular with unique double shell of silica Use both sexual amp asexual reproduction Do not have agella except for male gametes Important energy producers Oomycetesnot molds amp use external digestion Most are harmless decomposers but some can be serious plant pathogens RhizariansAll unicellular amp aquatic Foraminiferansfossilize easily Tiny organisms in shells Excavatesvery diverse includes organisms that do not even have mitochondria Diplomonads amp parabasalidslack of mitochondria likely a derived trait Euglenidscan be heterotrophs or photoautotrophs Reproduce solely through binary fission Plantae Amoebozoanscontain amoebas amp the slime molds Loboseans fit definition of classic amoebaquot All heterotrophic Plasmodial amp cellular slime molds Can exist asexually so long as there is enough food Ooze over particles engulfing food OpisthokontsContain fungi amp animals Ancient choano agellates are ancestral to animals October 14 2015 Lecture 14 Land plants mark a big shift in the organisms we ve discussed About 5 million years ago plants arrive Plants continually evolve to grow larger Bristlecone pines can live up to 500 years The invasion of land is one of the more complex feats in evolutionary history Drying out Structural support Reproduction Plants must find a long term way to survive in air need to stand without water supporting them and not dry out They also require new methods of reproduction Adaptations Embryophythic Need embryos to stay moist Cuticle Keep moisture in Stomata Small holes that open to let moisture in and close to keep plant from drying out Pigmentation Blocks UV radiation in absence of water Fungal relationship Develop mutual relationship with fungi that help plants absorb nutrients from soil Tracheid cells Allow for transfer of water amp nutrients throughout plant amp allow them to become larger Thick spore walls Protect plant from drying out Seeds Ultimate embryo protection Notable differences from Animals Diplontic life cycleonly diploid stage that s multicellular or undergoes mitosis Haplodiplontic life cycle alteration of generationsgametophytic multicellular haploid organism alternates with sporophytic multicellular diploid organism Sporophyte Meiotic event represents change from diploid to haploid Gametophyteproduces gametes through mitosis When gametes fuse we call it syngamy or fertilization Represents transition from haploid to diploid generation Everything below this point is 2N Two Points Spores amp gametes both swim Makes a lot of sense in aquatic environment but requires a lot of adaptation for land plants Relative length of the diploid amp haploid generation vary considerably between the different plant groups Different life cycles for different plants Mossesgametophytic stage is dominant phase why sporophytic stage is short Seed plants are just the opposite We believe this happens because haploid phases are very sensitive to deleterious mutations as these are not masked by a second allele as they would be in a diploid organism What Exactly is a Plant All land plants are included Some include green algae others even include red amp brown algae For the sake of this course plants land plants Closest relative to green plants is red algae Primary vs Secondary Endosymbiosis PrimaryEukaryotic Cell engulfs bacteria amp codependence develops A bacterium takes on functions of the cell SecondaryEukaryotic cell that engulfed another eukaryotic cell which had already engulfed bacteria Chloroplasts result from Primary Endosymbiosis a single event that gave rise to red amp green algae two membranes Brown algae is an example of a secondary endosymbiosis engulfed red or green algae to get their chloroplasts three membranes Land plants all arise from green algae lineage amp therefore are all photosynthetic using chlorophyll Green algae evolved chlorophyll B Green Plants Include both land plants amp all green algae Chlorophytes Contain most species of green algae Flattened cell form Contain both unicellular organisms amp complex mobile organisms Stoneworts Thought to be most closely related to land plants All show branching apical growth growth only from the tip of the organism common in all land plants The transition to Land Moss is most ancestral land plant Group Species Number Nonvascular plants liverworts 25000 hornworts mosses Seedless Vascular Plants lycopjytes 13000 horsetails ferns Non owering seed plants 9OO Gymnosperms Flowering plants angiosperms 250000 Bryophyte Facts Embryotic Gametophyte dominant Sporophyte dependent on gametophyte Require water for sexual reproduction Mosses are most recognizable bryophytes Most people wouldn t recognize moss as a sporophyte System of Transport Xylemmoves water amp minerals upwards through the plant Phloemmoves sugar amp nutrients down Provide structural support for the plant Tracheophyte Gametophytes are very small Club mosses Simple leaflike structures About 11hundred species of club mosses Vascular plants regular mosses are not vascular Monilophytes Monophyletic group of vascular plants Sister group to seed plants First group to have more complex leaf veins megaphils Horsetails Photosynthetic stems but no leaves Readily dividing set of cells at each segment Ferns Can vary widely in size some species with sporophytes less than 1 cm some are 24 meters tall Sporophyte is green part of the plant Soribrown spots under leavesclusters of sporangia that release spores
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