Course Hero Logo

New species appear by speciation species disappear by

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 10 - 12 out of 19 pages.

New species appear byspeciation. Species disappear byextinctionSpecies come and go. Species last 1millionyears on average. But it varies among groupsIt is estimated that more than 99% of all species that ever lived on Earth, amounting to over 5billion species, are not extinctThe ultimate fate of all Earth's species isextinction.For example, the average lifespan of amammal species is 4 million yearsThe Fabric of LifeThecellis the structural and functional unit of all living organismsProkaryotesare cells that do not have a true nucleusEukaryotesare cells that have a nucleusCells combine to formorgans,organs combine to form individual multi-celledorganismsThe condition for lifeGrowth:Metabolism is the suite of chemical reactions that life forms use to convert atoms andenergy into more cell materialReproduction:cells carry information in the form of DNA molecules that is passed from onegeneration to the next. Genetic material canmutate(a copy with errors), providinggeneticvariations.Mutations producechemical noveltyLife is aself-sustaining chemical systemcapable of incorporatingnoveltyand undergoingDarwinianevolutionCarbon-based lifeCarbon(6 protons, 6 neutrons, 6 electrons), the mostversatile chemical element, with diversemolecular functions,provide thebuilding block of lifeCarbon has the ability tobondwith other carbon atoms as well as many other elements, notablyhydrogen, oxygen, nitrogen, and sulfurOrganic material can formlong chainsof atoms,interlocked rings,and complexmoleculararrangements, the backbone of proteins and carbohydrates, of fat, oils, of DNA and RNA
11Organic matterPossibly the most fundamental compositional distinction is that oforganicandinorganicmatterOrganic applies specifically to compounds consisting of carbon atoms bonded together bycovalent bondsIn addition organic implies that the compound isbioticin originA common characteristic of organic compounds is their tendency to occur in long chain-likestructures calledpolymersImportantbiopolymersin the Earth system:oProteins:chains of bonded amino acidsoNucleic acids: (ex: DNA) built of nucleotidesoCarbohydrates:the basis for most food we eat, a carbon-hydrogen-oxygen compoundMolecular evolutionAlthough the details are still unknown,biogenesismust have proceeded in incremental steps,each with addedmolecular and chemical complexity1.First,pre-biotic molecules,the building blocks of cells, must come to existence2.Molecules would have to beselected, concentrated,andorganizedinto life's essentialstructures: a membrane protectedcell3.Molecular functionsshould have includedreproductionwith passing of (sometimeserroneous)information4.Natural selectionandmolecular evolutionis the ultimate step for the emergence oflifeBuilding blocks of lifeAnywherecarbon dioxide(CO2) andwater(H2O) interact in the presence of a sustainableenergy source the building blocks of life form:oLightningin the atmosphereoVolcanic activitynear the seafloor boiling the oceanoSolar radiationin the molecular clouds of the solar nebulaPre-biotic moleculeswere ubiquitous, raining from the sky and rising from the bottom of thesea, Every year, tons of organic material rain on Earth's surface from outer spaceBuilding blocks of life may presumably be found all around the

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 19 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
PLATT,DAVIS
Tags
Plate Tectonics, Volcano, Seismic Waves

Newly uploaded documents

Show More

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture