BIOL 112 1st Edition Exam 2 Study Guide Lectures 8 14 Lecture 8 February 11 Documented Therio example of speciation with intermediate types in fossil record S yellowstonensis descendent from S niagarae Centric diatom alga found only in Lake Yellowstone Diatom species defined by details of silica cell wall structures Uses for systematics Aids understanding of structures and functions of components and organs Aids understanding of evolution and family tree of organisms good systematics should reflect evolutionary history Aids rapid identification of relatives of previously unknown organisms Provides a framework to learn and remember different types of organisms Taxonomy science of naming organisms and groups of organisms one part of the larger activity which is systematics Systematics science of developing and evaluating classification schemes Linnaean Innovations Linnaean system of classification what we see today as systematics Brevity of writing style Development of and focus upon concept of species as fundamental biological unity Formal rules of binominals Two words always Latin or Classical Greek Why It is impartial to certain countries since they are dead languages Most education systems makes it essential to become fluent in these Always italicized or underlined Always used as a pair of words First word Genus name Second word specific epithet or specific descriptor Domain Kingdom Phylum Class Order Family Genus Species Lecture 9 February 13 Develop a scheme of organization which reflects the phylogeny evolutionary family tree of organisms Create monophyletic categories All organisms in category taxon have immediate common evolutionary ancestry including ancestors Avoid polyphyletic or paraphyletic taxa Paraphyletic leave creatures out of the taxa that make the data invalid Polyphyletic include other taxa that isn t homologous with the data has a different lineage Domains reflect major structural biochemical and molecular DNA sequences categories of life D Bacteria Prokaryotic familiar biochemistry D Archaea Prokaryotic less familiar biochemistry D Eukarya Eukaryotic forms Archaeans closer in many features to eukaryans than than they are to bacteria LUCA last universal common ancestor Lecture 10 February 18 Cell Wall present in most prokaryotic forms Cell wall prevents osmotic swelling bacteria usually live in hypotonic environment for this reason Complicated polymer of amino sugar and short amino acid chains Components N acetyl glucosamine N acetyl muramic acid bacteria specific Peptides All components are covalently cross linked into a giant polymer so that the cell wall is one large macromolecule called a peptidoglycan Two basic arrangements of cell wall components Gram Positive Thicker cell wall 20 nm wall is 90 peptidoglycan lipid content low 0 2 Highly resistant to ethanol extraction so gram stain will remain in cell and leave darkly stained cell Purple Blue Gram Negative Thinner cell wall 10 15 nm contains only 20 peptidoglycan higher lipid content 10 20 High lipid content makes wall sensitive to ethanol extraction so most of the gram stain will be removed and leave weakly stained cell Pink Gram positive cells are especially sensitive to penicillin Penicillin inhibits enzymes that synthesize cross links in wall Gram negative cells are less sensitive to penicillin Lecture 11 February 20 Heterotrophy Symbionts Some prokaryotes live in association with other organisms derive carbon nutrients from living organic matter host Mutualism relationship is ben eficial to both partners Commensalism one symbiont benefits while the host is neither harmed nor helped Parasitism Symbiont benefits host is harmed Prokaryotic para sites are also known as pathogens disease causers Domain Archaea Very ancient like forms have a number of fundamental differences from true bacteria which distinguish them Cell Walls variable content Many use proteins in cell wall No peptidoglycan Cell Membrane Lipid content differs some lipid moieties are branched Ribosomes and RNA polymerase more like eukaryotic forms than other prokaryotes drug sensitivity also eukaryote like Lecture 12 February 25 Molecular homologies link most chloroplast genomes most closely to cyanobacteria blue green algae This could mean that most modern chloroplasts arose from one original cyanobacterial like ancestor or that several times with closely related cyanobacteria Eukaryotic Life Cycle Alternation between haploid and diploid phases of life cycle with sexual events meiosis and fertilization between phases The X scheme Diploid Phase 2n sporophyte phase of meiosis and spore formation Haploid Phase n gametophyte phase of gamete formation for fertilization Body Plan Bilateral Symmetry implies several axes Anterior Posterior A P Dorsal Ventral D V What are the molecular bases of these axes as they develop during embryogenesis How did these control systems evolve Important Features Body axes A P d v L R What are the genetic bases of development of this body plan Cephalization Making a head Genetic basis of collection of sensory organs and brain in head Lecture 13 February 27 Beginning about 550 x 10 6 years ago appearance of most modern animal phyla over 10x10 6 year period At Cambrian Explosion fossil animals become common because we now see shells and skeletons things more easily preserved Ancestral Bilateral General agreement that common ancestor to modern bilaterian phyla is most likely something like a flatworm Has bilateral symmetry A P and d v axes Bilateral symmetry implies cephalization development of a head brain cluster of sensory organs on anterior Three tissue layers formed by gastrulation Phylum Chordata Vertebrates are sub phylum within this phylum Very old early chordates seen in Burgess Shale Distinguishing Characteristics of this Phylum Presence of a notochord at some time in life cycle Dorsal hollow nerve cord nervous system spinal cord Presence of pharyngeal slits at some time in development Presence of post anal tail Lecture 14 March 4 Kingdom Plantae Multicellular mostly macroscopic mostly autotrophic Cell walls made up of cellulose Multiple tissue cell types organized into stereotyped structures stems leaves roots Some members vascularized xylem and phloem Most species terrestrial or secondarily aquatic marine habitats At least 500 000 species From primitive ancient to advanced derived plant taxa evolutionary trends Increasing complexity of organization of body Increasing importance of the diploid phase of