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LIFE Evolution:theprocessofchangethataccountsfortheunityanddiversity oflife • Fundamentalcharacteristics=theabilityto: o Reproduce o Growanddevelop o Respondtostimuli o Metabolise o Containingchemicals § Carbohydrates(forstorage,energyandstructure),proteins, nucleicacids(geneticinformation),lipids(energystorage, structure) o Containingcells CLASSIFYINGLIFE • Wasafive-kingdomsystem(plants,fungi,animals,protista,monera) • Now:threekingdoms o RibosomalRNAusedtodistinguish o Bacteria,archaea,eukarya § Eukarya=plants,fungi,animals(containmembraneenclosedorganelles) § Prokarya=muchsimpler,microscopic,nopropernucleusor membrane-boundorganelles,reproducebybinaryfission • Bacteriaandarchaeaareprokarya • Somearchaeaareextremophiles(thermophiles, halophilesormethanogens) ORIGINSOFLIFE • Abioticsynthesis(ofsmall,organicmolecules):joinàmacromolecules, packageàprotobionts(evolutionaryprecursorofprokarya)àoriginof self-replication • Macroevolutionarychangesshowninfossilrecordàvertebrates, photosynthesis,impactsofextinction • Evidenceofcommonbeginnings: o DNAoccursinallorganisms o Similarcellstructures o Ciliaaresimilaronparameciumbacteriumandwindpipecells o Mammalianforelimbshavefivefingers o Vertebrateembryosappeartobesimilar o SimilaritiesinDNAofspecies(humans,monkeys) SELECTION • Darwin:“descentwithmodification:duetonaturalselection o Dualityofunityanddiversity o Traitspassedfromparenttooffspring o Successionofancestors DRAKE’SLAW: • Onemutationoccursineveryreplication • CELLS BACTERIA: • • • • • Cytoplasmicmembrane Upto10μminsize Growincolonies,reproducebybinaryfission (asexual,tomakeclones) Haveacellmembrane,DNA(inanucleoid), cytosol,ribosomes,cellwall(sometimes), flagella,fimbriae/cilia,capsule Coccus,coccobacillus,vibrio,rod,spirillum, spirochete ARCHAEA: • Haveacellmembrane,cellwall • ThreetypesofRNApolymerases(likeeukarya) • Maybeextremophiles • Shapeandsizesimilartobacteria(coccus/rod) • Singleloop(plasmid)DNA,nonucleus EUKARYA: • Cytoplasmcontainingsalts,mineralsetc. • Nucleus=controlcentre,withnucleolus,nucleoplasminside,doublemembranenuclearenvelopetocontaineverything,chromatin(DNA moleculesandproteins) • Ribosomes=nomembrane,translateRNAintoprotein • Mitochondria=forenergy(ATPproduction) • Chloroplasts=inplantsonly,forphotosynthesisforATPproduction • Endoplasmicreticulum o Rough=proteinsynthesis o Smooth=lipidsynthesisandtransport • Golgibody=modifies,packagesandsendsproteins • Lysosomes=moleculebreakdown(containenzymes) • Membrane=controlsmovementofmaterialsinto/outofcell,shape • Cytoskeleton o Proteinfilaments, microtubulesinthecell o Forshape,intracellular organisation,movement o Microfilaments=on membrane,pinching causesmuscle contraction o Intermediatefilaments= forstructure,anchors organelles o Microtubules=tracksformotorproteins,madeoftubulin, ‘powerhouse’forflagellaandcilia,about25nmdiameter ENDOSYMBIOSIS • Originoforganellesfrompriorstructures • • o Evidence=membranesimilarities,methodofdivision(binary fission),containownDNAandribosomes Largerprokaryoteengulfsasmalleroneàdouble-membrane,mutualism relationship Invagination(foldingin):abacterium(anaerobic,photosynthetic) absorbedbyanorganism,mitochondrion/chloroplastresults