Ch. 14 The History of LifeCh. 14 The History of Life

BiologyBiology

Mr. JonesMr. Jones

History of the EarthHistory of the Earth

Formed 4.6 billion year ago Started as hot ball of rock Earth cooled 4.4 bya First life began between 3.9 and 3.4 bya

FossilsFossils

Evidence of an organism that Evidence of an organism that lived long agolived long ago

PaleontologistsPaleontologists• Study ancient lifeStudy ancient life• Uses fossils to:Uses fossils to:

understand events that happened long agounderstand events that happened long ago Determine the kinds of organisms that Determine the kinds of organisms that lived during the past and their lived during the past and their behaviorsbehaviors

Study ancient climate and geographyStudy ancient climate and geography

How fossils formHow fossils form

1.1. Organisms are buried in mud, sand, or Organisms are buried in mud, sand, or clayclay

2.2. Sediments cover the organism, slows Sediments cover the organism, slows decompositiondecomposition

3.3. Minerals from sediments seep into bodyMinerals from sediments seep into body4.4. Over time, sedimentary layers compressed Over time, sedimentary layers compressed

into rockinto rock5.5. Mineral replace the body’s bone materialMineral replace the body’s bone material6.6. Earth’s movement or erosion expose the Earth’s movement or erosion expose the

bodybody7.7. Rocks form at relatively low temperatures Rocks form at relatively low temperatures

and pressure and pressure • Prevent damage of organismPrevent damage of organism

Types of FossilsTypes of Fossils

Trace fossilsTrace fossils• An indirect An indirect evidence left by evidence left by an animalan animal

• Include a Include a footprint, a footprint, a trail, or a trail, or a burrowburrow

CastsCasts• A replica or castA replica or cast• Minerals in rocks Minerals in rocks fill a space left fill a space left by a decayed by a decayed organismorganism

MoldsMolds• An empty space An empty space left by an left by an organisms after organisms after it decaysit decays

PetrifiedPetrified• Minerals Minerals penetrate and penetrate and replace the hard replace the hard parts of an parts of an organismorganism

PermineralizedPermineralized• Void spaces in Void spaces in original organism original organism is filled by is filled by mineralsminerals

Petrified

Permineralized

Original RemainsOriginal Remains

Amber-preserved Amber-preserved or frozenor frozen• An entire An entire organism quickly organism quickly trapped in ice or trapped in ice or tree sap and tree sap and hardenshardens

Amber preserved

Frozen

Dating fossilsDating fossils

Relative datingRelative dating• uses the position of fossils in

sediment layers• oldest fossil at the bottom

layer, youngest on top• Can only determine whether one

fossil is older than another• Cannot determine the actual age• Principles of Superposition &

Uniformitarianism

Absolute DatingAbsolute Dating

Radiometric datingRadiometric dating• use radioactive isotopes (atoms

with unstable nuclei that break down or decay)

• decay of each radioactive element is known and continues at a steady rate

Absolute DatingAbsolute Dating Half-life

• the time it takes a radioactive element to get to half its original amount

• Potassium 40 - 1.3 billion yrs• Carbon 14 - 5730 years

Geologic Time ScaleGeologic Time Scale

a type of calendar based on the different types of living organisms that have appeared on Earth

Precambrian EraPrecambrian Era Starts 4.7 byaStarts 4.7 bya Accounts for 87% of Earth’s Accounts for 87% of Earth’s historyhistory

Oldest rock dates 3.4 bya Oldest rock dates 3.4 bya Unicellular prokaryotes Unicellular prokaryotes appearedappeared

Eukaryotes appeared 2.1 byaEukaryotes appeared 2.1 bya Ended 345 myaEnded 345 mya

Oldest rock from Yukon, 4 byo

Paleozoic EraPaleozoic Era 345 to 248 mya345 to 248 mya Appearance of plants and animals including Appearance of plants and animals including

fishes, reptiles, amphibians and fernsfishes, reptiles, amphibians and ferns 90% of Earth’s marine species and 70% of 90% of Earth’s marine species and 70% of

land species disappearedland species disappeared

Mesozoic EraMesozoic Era 248 to 65 mya248 to 65 mya

• TriassicTriassic OldestOldest Mammals appearedMammals appeared Dinosaurs first Dinosaurs first appearedappeared

• JurassicJurassic Age of dinosaursAge of dinosaurs

• CretaceousCretaceous Mammals and Mammals and flowering plantsflowering plants

Dinosaurs and 2/3 Dinosaurs and 2/3 of living species of living species became extinctbecame extinct

Theory of Continental DriftTheory of Continental Drift

Continents were joined in a Continents were joined in a landmass known as Pangaealandmass known as Pangaea

Pangaea broke apart resulting Pangaea broke apart resulting in two large massesin two large masses

At the end of the Mesozoic, At the end of the Mesozoic, most of the continents had most of the continents had taken on their modern shapestaken on their modern shapes

Explained by plate tectonicsExplained by plate tectonics• Movement of the continentsMovement of the continents

The Origin of LifeThe Origin of Life

The Early IdeasThe Early Ideas

Spontaneous generationSpontaneous generation• Nonliving material can produce lifeNonliving material can produce life

Experiments to disprove this Experiments to disprove this theorytheory• Francesco RediFrancesco Redi

Used maggots in covered and uncovered Used maggots in covered and uncovered jarsjars

• Louis PasteurLouis Pasteur Used curved flasks with heated brothUsed curved flasks with heated broth

Francesco RediFrancesco Redi

• 16681668• Showed that Showed that rotting meat kept rotting meat kept away from flies away from flies would not produce would not produce new fliesnew flies

• Maggots appeared Maggots appeared only on meat that only on meat that had been exposed had been exposed to fliesto flies

Eggs laid on meatEggs laid on meat

Louis PasteurLouis Pasteur

Mid- 1800sMid- 1800s Used curve-necked Used curve-necked flasksflasks

Microorganisms were Microorganisms were prevented from prevented from entering the flaskentering the flask

When curved necks When curved necks were broken, broth were broken, broth became cloudy with became cloudy with microorganimsmicroorganims

BiogenesisBiogenesis

All living things come from All living things come from other living thingsother living things

Became cornerstone of biology Became cornerstone of biology after Pasteur’s experimentafter Pasteur’s experiment

The Modern IdeasThe Modern Ideas

Alexander OparinAlexander Oparin• Life began in the oceans that Life began in the oceans that formed on early Earthformed on early Earth

• Energy from sun + lightning+ Energy from sun + lightning+ Earth’s heat = simple compounds Earth’s heat = simple compounds (eg. amino acids)(eg. amino acids)

• Earth cooled, water vapor Earth cooled, water vapor condensed to form lakes and seas, condensed to form lakes and seas, compounds collected in the watercompounds collected in the water

Stanley Miller Stanley Miller and Harold Ureyand Harold Urey

Used Oparin’s Used Oparin’s hypothesis to hypothesis to setup experimentsetup experiment

Produced amino Produced amino acids and other acids and other organic organic compoundscompounds

Formation of ProtocellsFormation of Protocells

Sidney FoxSidney Fox Produced protocellsProduced protocells

• Large, ordered Large, ordered structure, enclosed structure, enclosed by a membraneby a membrane

• Carries out some Carries out some life activities life activities (growth and (growth and division)division)

Heated amino acidsHeated amino acids

The First True CellsThe First True Cells

Prokaryotes evolved from a Prokaryotes evolved from a protocellprotocell• HeterotrophsHeterotrophs• AnaerobicAnaerobic

ArchaebacteriaArchaebacteria• ProkaryoticProkaryotic• AutotrophsAutotrophs

Made glucose by chemosynthesisMade glucose by chemosynthesis

• Lived in harsh environmentsLived in harsh environments• Deep-sea vents and hot springsDeep-sea vents and hot springs

Photosynthesizing prokaryotesPhotosynthesizing prokaryotes• Increased oxygen in atmosphereIncreased oxygen in atmosphere

Eukaryotes evolved from Eukaryotes evolved from prokaryotesprokaryotes

Endosymbiont TheoryEndosymbiont Theory

Eukaryote provided beneficial Eukaryote provided beneficial environmentenvironment

Prokaryote provided method of Prokaryote provided method of energy synthesisenergy synthesis

Endosymbiotic, aerobic Endosymbiotic, aerobic prokaryotes evolved into modern prokaryotes evolved into modern mitochondriamitochondria

Photosynthetic cyanobacteria Photosynthetic cyanobacteria evolved into chloroplastsevolved into chloroplasts