history of life on earth
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History of Life on Earth. Chapter 12. The Age of the Earth. 4.5 billion years old Radiometric dating Radioactive isotopes break down over time Half-life – time it takes for half of amount to decay Using this can estimate age of earth - PowerPoint PPT PresentationTRANSCRIPT
History of Life on History of Life on EarthEarth
Chapter 12Chapter 12
The Age of the EarthThe Age of the Earth 4.5 billion years old4.5 billion years old
– Radiometric datingRadiometric dating– Radioactive isotopes break Radioactive isotopes break
down over timedown over time– Half-life – time it takes for Half-life – time it takes for
half of amount to decayhalf of amount to decay– Using this can estimate age Using this can estimate age
of earthof earth Non-living chemicals Non-living chemicals
reacted and produced reacted and produced organic moleculesorganic molecules
Combination of chemicals Combination of chemicals and energy from and energy from lightning/heat/Sun’s UV lightning/heat/Sun’s UV created organic created organic moleculesmolecules
2 Theories about how2 Theories about how
Primordial SoupPrimordial Soup Oceans filled with Oceans filled with
organic moleculesorganic molecules Sparks simulate Sparks simulate
lightninglightning Amino acids, fatty Amino acids, fatty
acids. And other acids. And other hydrocarbons hydrocarbons formedformed
1 problem: no 1 problem: no ozone to protect ozone to protect from UV, certain from UV, certain compounds couldn’t compounds couldn’t have existedhave existed
Bubble ModelBubble Model Gases from undersea Gases from undersea
volcanoes trapped in volcanoes trapped in bubbles that protect bubbles that protect them from UV and them from UV and concentrate themconcentrate them
Reactions happen Reactions happen fasterfaster
Bubbles rise, burst, Bubbles rise, burst, release compoundsrelease compounds
Energy from UV and Energy from UV and lightning creates lightning creates more reactionsmore reactions
Complex organic Complex organic molecules fall into molecules fall into ocean and start ocean and start againagain
Precursor of 1Precursor of 1stst Cells Cells
Molecules of life can arise from simple Molecules of life can arise from simple chemistrychemistry
RNA can be made in labRNA can be made in lab RNA believed to be 1RNA believed to be 1stst self-copying self-copying
information storing moleculeinformation storing molecule Makes proteins and changes from Makes proteins and changes from
generation to generation; acts as an generation to generation; acts as an enzymeenzyme
MicrospheresMicrospheres– Amino acid chains Amino acid chains
form droplets in form droplets in waterwater
CoacervateCoacervate– Droplet made of Droplet made of
different kinds of different kinds of molecules like amino molecules like amino acids and sugarsacids and sugars
These are steps These are steps toward cellular toward cellular organizationorganization
Microspheres last Microspheres last longer and longer longer and longer and bring other and bring other molecules inmolecules in
Origin of HeredityOrigin of Heredity
DNA came after RNADNA came after RNA RNA catalyzed early proteinsRNA catalyzed early proteins Many believe RNA was brought into Many believe RNA was brought into
microsphere and could pass traits onmicrosphere and could pass traits on But how DNA, RNA, and hereditary But how DNA, RNA, and hereditary
mechanisms first developed is still mechanisms first developed is still not knownnot known
12.2 The Evolution of Cellular 12.2 The Evolution of Cellular Life:Life:
ProkaryotesProkaryotes Fossil preserved or Fossil preserved or mineralized remains mineralized remains or imprints of an or imprints of an organism that lived organism that lived long agolong ago
Oldest (2.5 billion Oldest (2.5 billion years old) years old) photosynthetic photosynthetic prokaryotes - prokaryotes - cyanobacteriacyanobacteria
Created oxygen but Created oxygen but took millions of years took millions of years to build up to current to build up to current amount amount
Two Groups of Bacteria Split Very Two Groups of Bacteria Split Very Early Early
EubacteriaEubacteria– Peptidoglycan in Peptidoglycan in
cell wallscell walls– Many cause disease Many cause disease
and decayand decay
ArchaebacteriaArchaebacteria– No peptidoglycanNo peptidoglycan– Unique lipids in cell Unique lipids in cell
membranemembrane– Believed to Believed to
resemble ancient resemble ancient archaebacteriaarchaebacteria
Evolution of EukaryotesEvolution of Eukaryotes
1.5 bya first eukaryotes showed up1.5 bya first eukaryotes showed up Larger; internal membranes; DNA in Larger; internal membranes; DNA in
nucleusnucleus– Mitochondria in almost allMitochondria in almost all– Chloroplasts in plants and protistsChloroplasts in plants and protists
EndosymbiosisEndosymbiosis
Theory states bacteria entered large Theory states bacteria entered large cells as parasites or undigested preycells as parasites or undigested prey
Begin to live inside host and Begin to live inside host and performed cellular respiration or performed cellular respiration or photosynthesisphotosynthesis
Mitochondria – descendents of Mitochondria – descendents of symbiotic, aerobic eubacteriasymbiotic, aerobic eubacteria
Chloroplasts – descendents of Chloroplasts – descendents of symbiotic, photosynthetic eubacteriasymbiotic, photosynthetic eubacteria
Support for EndosymbiosisSupport for Endosymbiosis Size and StructureSize and Structure
– Mitochondria like eubacteriaMitochondria like eubacteria– Chloroplasts like cyanobacteriaChloroplasts like cyanobacteria
Genetic MaterialGenetic Material– Circular DNA similar to bacteria is Circular DNA similar to bacteria is
different than hosts DNAdifferent than hosts DNA RibosomesRibosomes
– Similar in size to those of bacteriaSimilar in size to those of bacteria ReproductionReproduction
– Simple fission independent of hostSimple fission independent of host
MulticellularityMulticellularity All living things are broken into 6 kingdomsAll living things are broken into 6 kingdoms
– Eubacteria, Archaebacteria, Protista, Fungi, Plants, AnimalsEubacteria, Archaebacteria, Protista, Fungi, Plants, Animals Eubacteria and Archaebacteria oldest; single celled Eubacteria and Archaebacteria oldest; single celled
prokaryotesprokaryotes Protista – first eukaryotic kingdom, multicellular and Protista – first eukaryotic kingdom, multicellular and
unicellularunicellular All other eukaryotes, fungi, plants, and animals, came later All other eukaryotes, fungi, plants, and animals, came later
and all came from protistsand all came from protists
Unicellular is very successful Unicellular is very successful Almost every cell you can see is Almost every cell you can see is
multicellularmulticellular
Origins of Modern OrganismsOrigins of Modern Organisms Cambrian Explosion Cambrian Explosion
– Most animal phyla originated during late Most animal phyla originated during late Precambrian and early Cambrian periodsPrecambrian and early Cambrian periods
– Great evolutionary expansionGreat evolutionary expansion– Many unusual marine organisms appear that Many unusual marine organisms appear that
have no living relativeshave no living relatives
Burgess ShaleBurgess Shale 1909 geological formation in Canada 1909 geological formation in Canada
foundfound Ordovician Period – 505 mya – 438 myaOrdovician Period – 505 mya – 438 mya
– Trilobites – extinct 250 myaTrilobites – extinct 250 mya
Burgess ShaleBurgess Shale
Mass ExtinctionsMass Extinctions Large number of species become extinctLarge number of species become extinct 5 Major extinctions5 Major extinctions
– 440 mya440 mya– 360 mya360 mya– 245 mya – 96% of all species245 mya – 96% of all species– 210 mya210 mya– 65 mya – 2/3 of all land species65 mya – 2/3 of all land species
Today? Human activity might be causing Today? Human activity might be causing anotheranother– ½ of rainforests destroyed½ of rainforests destroyed– Keep up our current rate Keep up our current rate
22% to 47% of plants gone22% to 47% of plants gone 2,000 of the 9,000 birds 2,000 of the 9,000 birds
12.3 Life Invaded Land12.3 Life Invaded Land Ozone LayerOzone Layer
– Life evolved protected Life evolved protected in oceans from in oceans from dangerous UV rays dangerous UV rays from Sunfrom Sun
– No life on land during No life on land during Cambrian periodCambrian period
– 2.5 bya photosynthesis 2.5 bya photosynthesis puts Oputs O22 into air which into air which reacts and forms reacts and forms Ozone, OOzone, O33
– Blocks UVBlocks UV– Eventually enough to Eventually enough to
make it safe to live on make it safe to live on landland
Plants and Fungi on LandPlants and Fungi on Land 11stst organisms on land organisms on land
were probably a were probably a combination of plants combination of plants and fungi; 430 myaand fungi; 430 mya– Plants can make Plants can make
nutrients by nutrients by photosynthesisphotosynthesis
– Fungi can absorb Fungi can absorb minerals from rockminerals from rock
– Together called Together called mycorrhizae, these mycorrhizae, these exist todayexist today
Mutualism – 2 species Mutualism – 2 species live together and both live together and both benefitbenefit
Theory of EvolutionTheory of Evolution
Chapter 13Chapter 13
13.1 The Theory of Evolution 13.1 The Theory of Evolution by Natural Selectionby Natural Selection
Before Darwin most Before Darwin most people believed people believed each species was a each species was a divine creation divine creation existing as it was existing as it was when it was createdwhen it was created
But why were there But why were there fossils of unknown fossils of unknown organisms?organisms?
Jean Baptiste Jean Baptiste Lamarck 1809Lamarck 1809– Features of Features of
organisms change organisms change during life and are during life and are passed on to passed on to offspringoffspring
– Giraffe stretches Giraffe stretches neck to reach neck to reach leaves, offspring leaves, offspring have longer neckshave longer necks
WRONG!!WRONG!!
And now for DarwinAnd now for Darwin Charles Darwin was Charles Darwin was
from a wealthy familyfrom a wealthy family Studied medicine but Studied medicine but
became a minister became a minister (though he never (though he never became ordained)became ordained)
In 1831 Darwin went In 1831 Darwin went on a voyage on the on a voyage on the HMS HMS BeagleBeagle as a as a naturalistnaturalist
Galapagos Islands – Galapagos Islands – plants and animals plants and animals resembled those of resembled those of the coast of South the coast of South AmericaAmerica
Darwin believed the Darwin believed the organisms arrived organisms arrived from the coast and from the coast and changed once they changed once they were therewere there
Called this “descent Called this “descent with modification” with modification” which would which would become known as become known as evolutionevolution
Most famous were Most famous were the finches and the the finches and the tortoisestortoises
He studied the data He studied the data he collected for he collected for many yearsmany years
Things That Affected DarwinThings That Affected Darwin
Thomas Malthus Thomas Malthus essay 1798essay 1798– Human population Human population
was increasing faster was increasing faster than its food sourcethan its food source
– Unchecked Unchecked populations will grow populations will grow geometricallygeometrically
– Humans are checked Humans are checked by disease, war, & by disease, war, & faminefamine
Charles Lyell book Charles Lyell book – Principles of Principles of
GeologyGeology– Surface of Earth Surface of Earth
changed over timechanged over time
Populations are all of the individuals Populations are all of the individuals of a species that live in a specific of a species that live in a specific geographical area and can interbreedgeographical area and can interbreed
Darwin believed Malthus’s idea of Darwin believed Malthus’s idea of unchecked population growth applied unchecked population growth applied to all speciesto all species
““Individuals that have physical or Individuals that have physical or behavioral traits that better suit their behavioral traits that better suit their environment are more likely to environment are more likely to survive and will reproduce more survive and will reproduce more successfully than those that do not successfully than those that do not have such traits”have such traits”
Evolution By Natural SelectionEvolution By Natural Selection Natural Selection – Natural Selection –
Number of individuals Number of individuals with favorable with favorable characteristics that are characteristics that are inherited will increaseinherited will increase
Adaptations are Adaptations are inherited traits that inherited traits that become common become common because it produces a because it produces a selective advantageselective advantage
Publication of Darwin’s WorkPublication of Darwin’s Work 1831 – 1831 – BeagleBeagle voyage voyage 1844 – very low public 1844 – very low public
opinion of evolutionopinion of evolution 1859 – Another scientist, 1859 – Another scientist,
Alfred Russel Wallace, Alfred Russel Wallace, writes Darwin asking for writes Darwin asking for help to publish his work help to publish his work that describes natural that describes natural selection!!selection!!
Darwin publishes his Darwin publishes his work and people aren’t work and people aren’t happy to hear they are happy to hear they are “related to apes”“related to apes”
Major Points of TheoryMajor Points of Theory
Inherited variation exists within the Inherited variation exists within the genes of every population or speciesgenes of every population or species
In environments, some individuals In environments, some individuals are better suited and have more are better suited and have more offspringoffspring
Beneficial traits spreadBeneficial traits spread Evidence that living species evolved Evidence that living species evolved
from extinct organismsfrom extinct organisms
UPDATEUPDATE
Now know genes are responsible for Now know genes are responsible for inherited traitsinherited traits
Natural selection causes the Natural selection causes the frequency of certain alleles in a frequency of certain alleles in a population to increase or decrease population to increase or decrease over timeover time
Species FormationSpecies Formation Reproductive Reproductive
IsolationIsolation– 2 populations of the 2 populations of the
same species do not same species do not breed with each other breed with each other due to geographic due to geographic separation, difference separation, difference in mating periods, or in mating periods, or other barriersother barriers
– Eventually they may Eventually they may not be able to breed not be able to breed with each otherwith each other
– Kaibab squirrel and Kaibab squirrel and Abert squirrelAbert squirrel
Tempo of Tempo of EvolutionEvolution
GradualismGradualism– Slow/gradual Slow/gradual
process of changing process of changing that occurs that occurs continuouslycontinuously
Punctuated Punctuated EquilibriumEquilibrium– Large changes that Large changes that
occur quicklyoccur quickly
13.2 Evidence of Evolution13.2 Evidence of Evolution FossilsFossils
– Many intermediate Many intermediate life forms have been life forms have been found in fossilsfound in fossils
– Not completeNot complete– Certain Certain
environments are environments are better for forming better for forming fossilsfossils
– Animals that live in Animals that live in areas that are not areas that are not good for fossils are good for fossils are missingmissing
– Studied by Studied by paleontologistspaleontologists
Anatomy and developmentAnatomy and development– Comparisons can show similaritiesComparisons can show similarities– Vestigial structuresVestigial structures
Structures that have no use or have a less important Structures that have no use or have a less important function than they do in other related organismsfunction than they do in other related organisms
Whale’s hind limbsWhale’s hind limbs Humans appendixHumans appendix
Vestigial StructuresVestigial Structures
Homologous Homologous StructuresStructures– Share a common Share a common
ancestryancestry– Similar structure in Similar structure in
different organismsdifferent organisms Development of Development of
EmbryosEmbryos– Believe you can see Believe you can see
evolutionary historyevolutionary history– At some point all At some point all
vertebrates have a vertebrates have a tail, buds that tail, buds that become limbs, and become limbs, and pharyngeal pharyngeal pouchespouches
EmbryologyEmbryology
Biological MoleculesBiological Molecules– ProteinsProteins
Smaller differences between closely related Smaller differences between closely related and larger between more distantly relatedand larger between more distantly related
– DNA sequencesDNA sequences Similar to relationships predicted by Similar to relationships predicted by
biologistsbiologists
13.3 Examples of Evolution13.3 Examples of Evolution
Factors in Natural SelectionFactors in Natural Selection– All populations have genetic variationAll populations have genetic variation– The environment presents challenges to The environment presents challenges to
successful reproductionsuccessful reproduction– Individuals tend to produce more Individuals tend to produce more
offspring than the environment can offspring than the environment can supportsupport
– Better suited individuals leave more Better suited individuals leave more offspringoffspring
Example of Natural Example of Natural SelectionSelection
Tuberculosis (TB) kills more adults Tuberculosis (TB) kills more adults than any other infectious diseasethan any other infectious disease
Antibiotics introduced in 50s now Antibiotics introduced in 50s now don’t work because bacteria are don’t work because bacteria are resistantresistant
Mutation in some bacteria made it Mutation in some bacteria made it resistant so it survived and passed on resistant so it survived and passed on genes and becomes more common in genes and becomes more common in populationpopulation
Evolution in Evolution in Darwin’s Darwin’s FinchesFinches– Darwin Darwin
collected 31 collected 31 specimens from specimens from 3 islands3 islands
– 9 distinct 9 distinct species all species all similar except similar except for billsfor bills Large bills fed Large bills fed
on seedson seeds Small bills ate Small bills ate
insectsinsects
Formation of New SpeciesFormation of New Species
Divergence – accumulation of Divergence – accumulation of differences between groupsdifferences between groups
Speciation – process by which a new Speciation – process by which a new species formsspecies forms
Subspecies – populations of the same Subspecies – populations of the same species that differ genetically because species that differ genetically because of adaptations to different living of adaptations to different living conditionsconditions– First step of speciationFirst step of speciation
SubspeciesSubspecies
Maintaining New SpeciesMaintaining New Species– When subspecies become different When subspecies become different
enough a reproductive barrier may formenough a reproductive barrier may form– Geographic isolationGeographic isolation– Different reproduction timesDifferent reproduction times– Physical differencesPhysical differences– Offspring not fertileOffspring not fertile