a. fungi help plant take up water, phosphorus, nitrogen and trace elementsb. plant gives fungi sugars/carbohydrates, fungi can reach out to maximal surface area to soil and bring nutrients back inc. this trade means plants get far more nutrients than they originally couldd. key symbiotic mutualismc. algae can photosynthesize and give sugar that fungus cant otherwise makeTopic 15: Principles of Multicellular Organismsa. Origins of Multicellularitya. Unicellular organisms unable to reach large sizes: physiochemicalb. Eukaryotes predisposed to evolved large, multicellular bodies: evolutionaryc. Mutlicellular lineage evolve similar body plans: Form- functionb. Physiochemical Constraintsa. Reduced surface area/volume ratio- inefficient gas exchange & nutrient uptakei. can’t diffuse enough material across the cell membrane to keep up with the demands of the cytoplasmb. increased distance from nucleusc. efficiency of internal supportc. Evolutionary Originsa. Simple colonies & filaments in prokaryotesb. Coordinate cell divisions, orientations, timing of cellular processesd. Key Features in eukaryotesa. Membrane bound organellesi. Higher metabolic demands to overcome limits of diffusionii. Want to have ability to make huge amounts of ATP rapidly for bulk flowb. End membranesi. Compartments for different metabolic activities: increased efficiencyii. Organize processes in a sequential manneriii. Localize reactionsc. Cytoskeletoni. Increases the critical sizeii. Internal supportiii. Movement of cells, organelles, and membranesiv. Major means of communication within the celle. Form Function Relationshipsa. Organisms exploit key features of eukaryotic large, complex body plansf. Colonialitya. Loose aggregation of ‘independent’ cellsb. Can reassemble at willc. Ex: Spongesi. Capable of regeneration and reaggregationg. Accellularitya. Repeated mitosis without cell divisionsb. Allows for very rapid transport by cytoplasmic streamingh. Multicellularitya. Tight association of cells for somatic (day to day functions) & reproductive (produce next generation) functionsb. Most common way of attaining large sizesc. Specialized cells, tissues, organs, and organ systemsd. Larger size frequently correlated with:i. Enhanced ability to garner resourcesii. Increased reproductive successi. Radial Symmetrya. Associated with low metabolic rates & low motilityb. 2+ planes of symmetryc. Ex: box jellyi. Use chemical warfare b/c they can’t get up and run awayj. Bilateral Symmetrya. Associated with elevated metabolic rates & frequently enhanced motilityb. 1 plane of symmetryk. Modularitya. Formation of new axes of growth: produces branching growth patternb. Increases control of substrate space & get more nutrientsc. Ex: fungid. How radial get biggerl. Segmentationa. Subdivisions of body into linear sequence of unitsb. Actions of segments coordinate for different functions for greater efficiencyc. How bilateral get biggerm. Serial Homologya. Homologous modules specialized for different functionsb. Tagmosis: segments with similar functions grouped together regional responsen. Plant Evolutiona. Persistent radial symmetry of 1 axisb. Repeated evolution of bilateral leaves on 2 axiso. Animal Evolutiona. Shift from radial to bilateral symmetry in derived animalsTopic 16: Origin and Evolution of Plantsa. Earliest land plantsa. Nonvascular that grew photosynthetic shoots above the shallow fresh waterb. Leafless shoots typically had waxy cuticles and few stomatai. Allowed them to avoid excessive water loss while exchanging CO2 andO2 for photosynthesisb. Evolved Land plantsa. Competition for light water and nutrients intensifiedb. Increase in surface area= greater need for waterc. Larger shoots required more anchoraged. Favored the production of multicellular, branching rootse. Natural selection favored plants capable of efficient long-distance transport of water, minerals, and products of photosynthesisc. Evolution of vascular tissuea. Xylem and phloem made it possible for the development of extensive root and shoot systems that carry out long-distance transportd. Why leave water?a. More light for photosynthesisb. Inorganic nutrients available on landc. Less crowded, fewer competitorse. Modularity allows adaptation to new situationsa. Indeterminate growth: Can repeat modules unchanged as many times as needed, plants can respond to conditionsb. Determinate growth: growth of limited durationTopic 17: Origin and Early Evolution of Animalsa. Animalsa. Multicellularb. Heterotrophic by ingestionc. Motilityd. Complex behaviore. Extracellular matrixf. Tight cell junctionsg. Hox genesb. Animal Evolutiona. Parazoai. Asymmetry or radialb. Radiatai. Radial symmetryc. Bilateriai. Most diverse groupc. Radial Symmetrya. Usually found in sessile or slow-moving animalsb. 360 sensory fieldc. limited mobilityd. low metabolic ratese. simple body plan: diploblasticf. organs typically absentd. Bilateral Symmetrya. Typically occurs in highly motile animals and have high metabolic ratesb. Cephalization: sense organs concentrations at anteriorc. Evolution of mesoderm: triploblasticd. High energy demandse. High speed movemente. Animal Origins- Pre Cambriana. Arose from protists- chaoanoflagellatesb. Ediacaran fauna- Avalon revolutioni. First revolution, bizarre body plans & symmetriesf. Animal Relationshipsa. Earliest: Parazoa- spongesb. Radiata: corals, jellyfishc. Protosomes: snails, earthworms, insectsd. Deuterosome- starfish, sharks, humanse. Separate developmental patternsi. Protosomes: mouth develops firstii. Deuterosomes: anus firstg. Cambrian Revolutiona. Bilateria arose prior to Cambrian (> 565 MYA)b. Acquisition of hard skeletons which increase the effect of musclesc. Increase in ability of animals to move fasth. Reasons for Cambrian occurringa. Higher levels of free oxygenb. Skeletonizationc. Evolutionary escalationi. Parazoasa. Totipotent cellsb. No distinct germ likec. Intracellular digestionj. Eumetazoansa. All animals except parazoans or spongesb. Radial symmetryc. Gastrulationd. True tissuesTopic 18: Building BodiesA. Conserved Sequencea. A genetic sequence that has changed very little over long period of potential evolutionb. Strong selection against mutationB. Gastrulationa. Cells can migrate and change shapeb. Cells have a fate depending on their locationc.C. Inductiona. Cells send chemical signals to each other: inducersb. Morphogenesis: occurs by cascade of induction eventsc. Cell will have different fates
View Full Document