Week of Feb 21 Notes, Quiz prep for Monday
Week of Feb 21 Notes, Quiz prep for Monday Bio131
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This 7 page Class Notes was uploaded by Graham Notetaker on Saturday February 27, 2016. The Class Notes belongs to Bio131 at Elon University taught by David Vandermast in Spring 2016. Since its upload, it has received 12 views. For similar materials see Biodiversity in Biology at Elon University.
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Date Created: 02/27/16
Week of Feb 21. Notes, Biodiversity with Dr. Vandermast Graham Kulig Protista “Protists are a diverse group of organisms that includes all eukaryotesexcept the land plants, fungi, and animals” Some Protists... ● Paraphyletic group (ancestor, and ome of its descendants) ● Morphological innovations occurred as protists diversified: ○ Nuclear envelope ○ Multicellularity, and structures that function in support and protection ○ Mitochondrion and chloroplast arose by endosymbiosis ● DIVERSITY IS KEY ○ Some reproduce sexually, some don’t ○ Some are photosynthetic, while others get their food from organic compounds ○ Mixotrophs ■ “can perform both autotrophic and heterotrophic functions” INTRODUCTION: ● There is no trait that is found in protists but no other organisms ○ No synapomorphies ○ PAY ATTENTION TO SYNAPOMORPHIES, WE WILL BE QUIZZED ON THEM ● All eukaryoticexcept for plants, animals, and fungi ● The common feature among protists is that they tend to live in environments where they are surrounded by water (including wet soils) ● The earliest eukaryotes were probably singlecelled with: ○ nucleus and endomembrane system, ○ mitochondria, ○ cytoskeleton, ○ no cell wall ○ These cells probably swam using a flagellum IMPACT ON HUMANS ● Irish Famine caused by a protist ● Causes Diseases ○ malaria ○ blindness from AIDS ○ dysentery ECOLOGICAL IMPORTANCE ● Low species diversity, but VERY abundant ● Are primary producers ○ They use photosynthesis to produce chemical energy ● Fix hal the world’s CO2...whoa! ● Protists play a key role inglobal carbon cycle and act as carbon sinks reduce global warming ○ “Fixation vs. sequestrati” ○ Fixation is the process of converting inorganic matter into organic carbon ○ Sequestration is CO2 being taken from atmosphere and stored as a liquid or solid for a long period of time. ● Carbon Sink ○ “long lived carbon reservoir” sedimentary rock or petroleum ● Phytoplankton (photosynthetic plankton) ○ Phytoplankton and other protists are most of the base of food chains in aquatic environments ● Planktonic ○ Can’t resist movement of water, just float around PHYLOGENETICS ● The first eukaryote split was betwenikonts and bikonts Opisthokonta and Amoebozoa form the monophyletic group Unikonta (one flagellum; kont=flagellum) – ○ The other five major lineages form the monophyletic group Bikonta (two flagella) ● The key to understanding the protist clades is to recognize the synapomorphies that occurred within protist lineages ○ Features of eukaryotic cells (all protists share these) ○ Primary endosymbiosis of the mitochondria and chloroplasts ○ Secondary endosymbiosis of chloroplasts in some protist lineages ○ Structures for support and protection are unique to various protist lineages ○ Alternation of generations in some lineages Endosymbiosis: ● Eukaryotic host supplied the bacterium with protection and carbon compounds , which the bacterium oxidized ● The host cell is proposed to be a predator capable only of anaerobic fermentation ● Primary endosymbiosis: ○ Bacteria engulfed, lives inside, leaks carbon and ATP, and provides for host ● Secondary endosymbiosis ○ occurs when an organism engulfs a photosynthetic cell and retains itchloroplasts ■ chloroplasts surrounded by membranes now ● Consistent observations with endosymbiosis theory... ○ Mitochondria about the same size of an average bacterium and replicate by fission, as do bacteria ○ Chloroplasts and mitochondria have their own ribosomes, double membranes, and own genomes Structures: ● Many have cell walls ● Some have shells, or tests ● Diatoms are surrounded by cell wall ● Dinoflagellat have cell wall composed of cellulose plates ● Alveolates have alveoli to stiffen structures Ingestive feeding ● Larger protistngulfinsmaller protists ● Some eat bacteria ● Feeding by engulfing is only possible ion't have a cell wall (because you gotta be flexible!) Absorptive feeding ● Some are decomposers (recyclers) ● Others are parasites and absorb from host Reproduction: ● Sexual reproduction: ○ Based on eiosis(must bedploid to get t) d ○ MUST BE DIPLOID ○ Produces gametes ○ Sex cells have n=23 to compliment other half the baby organism will be getting from other parent ● Asexual reproduction: ○ Based on mitosis ○ When you cut yourself...cells divide to replace lost ones using mitosis. ○ It is responsible for all the growth that makes us what we are ○ Mitosis 2n=4 split leaves two cells with 2n=4, identical to parent ○ Think duplicati not division ● Haploid: n=23 (gametes, sperm cells) ● Diploid: 2n=46 (majority of cells in body) ● Chromosomes come in pairs, living with 3 or 1 usually means death ○ 122 are called autosomes ○ 23 are sex chromosomes ○ Chromatids: DNA that has replicated itself Meiosis In depth: PMAT! ● Prophase: ○ Homologous chromosomes come together to form tetrad (4 chromatids together, process is called synapsis) During this, chromatids overlap and swap identical genetic information, and because this is 3D, they can overlap anywhere. This means the new chromosomes will not be identical to each other. ○ You get: one chromatid that is identical to dad paired with one that is mostly dad, some of mom. Vice versa for other chromosome. ● Metaphase: ○ Entire Chromosomes move to sides of cell anticipating split. ● Anaphase: ○ Pulled to poles ● Telophase/cytokinesis: ○ Split meiosis 1: homologs get pulled apart meiosis 2very much like mito, chromatids get pulled apart. producing gametes at end( sperm/egg cells) Alternation of generations: ● Multicellular protists have one phase of life that is based on a haploid form and another that is based on a diploid form: ○ This phenomenon is known asalternation of generations ● Multicellulahaploiis calledametophyte, producesametes by mitosis ● Multicellulaiplois callporophyte producessporesbyeiosis ○ Spore is a single cell. A spore divides by mitosis to form a haploid, multicellular gametophyte ● Isomorphic: When the gametophyte and sporophyte look the same ● Heteromorphic: sporophyte is giant, gametophyte is tiny ○ ***“We have some algae that demonstrate one of these two things. memorize them, and answer the question on the test correctly!!”
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