Download LIFE CELLS

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
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CELLS
BACTERIA:
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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
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o Evidence=membranesimilarities,methodofdivision(binary
fission),containownDNAandribosomes
Largerprokaryoteengulfsasmalleroneàdouble-membrane,mutualism
relationship
Invagination(foldingin):abacterium(anaerobic,photosynthetic)
absorbedbyanorganism,mitochondrion/chloroplastresults