Download Keyword/concepts: Definition: Darwin Charles Darwin theorised

Keyword/concepts:
Definition:
Darwin
CharlesDarwintheorised/arguedtheoriginofspeciesbymeansofnaturalselection.
Evolution
Thechange,overtime,inthegeneticcompositionofpopulations.
NaturalSelection
Theprocesswherebyorganismsbetteradaptedtotheirenvironmenttendtosurviveandproducemoreoffspring.*
Adaptationbynaturalselectionoccursinapopulationwhenthereisexcessreproduction,geneticvariationandgenetictraitsthathavedifferent
fitnessinaparticularenvironment.
CellTheory
Allorganismsaremadeofcellsandtheproductsofcells.Allcellscomefrompre-existingcells.Thecellisthesmallestlivingorganisationalunit.
Cambrianexplosion
Therelativelyshortevolutionaryevent,beginningaround542millionyearsagointheCambrianPeriod,duringwhichtheappearanceofcomplexcells
andorganismsoccurred,asindicatedbythefossilrecord.
Stromatolites
Acalcareousmoundbuiltupoflayersoflime-secretingcyanobacteriaandtrappedsediment,foundinPrecambrianrocksastheearliestknownfossils,
andstillbeingformedinlagoonsinAustralasia;Formedinshallowwaterbythetrapping,bindingandcementationofsedimentarygrainsbybiofilms
(microbialmats)ofmicroorganisms,especiallycyanobacteria.
Prokaryotes
(Nonucleus)Amicroscopicsingle-celledorganismwhichdoesnothaveadistinctnucleuswithamembranenorothermembraneboundorganelles.
E.g.bacteriaandcyanobacteria.Prokaryoticcellshaveasimplestructureandlackinternalcompartments.
Eukaryotes
(Hasanucleus)AnorganismconsistingofacellorcellsinwhichthegeneticmaterialisDNAintheformofchromosomescontainedwithinadistinct
nucleus.IncludealllivingorganismsotherthanBacteriaandArchaea.Eukaryoticcellscontainintracellular,membrane-boundcompartments,which
separatedifferentmoleculesandmetabolicreactions.Cellwithanucleusandothermembrane-boundorganelles.
Cell
Thesmalleststructuralandfunctionalunitofanorganism,typicallymicroscopic;consistsofcytoplasmandanucleusenclosedinamembrane.
CellMembrane
Asemi-permeablemembranesurroundingthecytoplasmofthecell,maintainingthecontentsofthecellandregulatingthemovementofsubstance
inandoutofthecell.Selectivelypermeable,fluidmosaicstructuresthatarecomposedofaphospholipidbilayercontainingproteins,glycoproteins
andglycolipids.Theboundaryoflivingcellsseparatingacellfromitsenvironment;formedfromaphospholipidbilayer.
Archaea
Domain;includesmanybacterialspeciesthatliveinextremeconditions,suchassalty(halophiles),acidic(acidophiles)orhot(thermophiles)
environments.Auniquegroupwithinthisdomainaremethanogenicbacteria;anaerobesthatproducemethaneasametabolicby-product.
Biochemically,ArchaeaarenearlyasdifferentfromBacteriaastheyarefromEukarya(makingthemaseparatedomain).Genetictranscriptionand
translation,aremoresimilartothoseofeukaryotesthanbacteria.Nowknowntobefoundeverywhere.Archaeanshavenotbeenfoundtoproduce
restingspores.Furthermore,asof2015,noclearexamplesofArchaeanpathogensareknown.
Bacteria
Domain;adiversegroupofprokaryotesthatsharemanyhabitatswithorliveonandinhumansaswellasotherplants&animals.
Cyanobacteria
Animportantsubgroupthatcontainchlorophyllandarephotosynthetic.Aidedoxygenationofplanetearth.
Cytoplasm
Interiorofthecell.Thecytosolandorganellesofeukaryoticcells,excludingthenucleus.
Ribosome
Siteofproteinsynthesis;mRNAtranslatestoproteins;proteinsynthesis;amountofribosomeshowactivethecellisi.e.themoreribosomes,more
metabolicallyactive.Cytoplasmicorganellewhereproteinsynthesisoccurs;formedfromtworRNAsubunitsinassociationwithanmRNAmolecule.
Protein
anyofaclassofnitrogenousorganiccompoundswhichhavelargemoleculescomposedofoneormorelongchainsofaminoacidsandarean
essentialpartofalllivingorganisms,especiallyasstructuralcomponentsofbodytissuessuchasmuscle,hair,etc.,andasenzymesandantibodies.