Opener…Wednesday!!! 12/16Opener…Wednesday!!! 12/16

Please list FIVE things you want to Please list FIVE things you want to know about evolution & the know about evolution & the

history of the EARTH.history of the EARTH.

Ch 14: History of Life

14.1 Biogenesis

What’s BIO-GENESIS?What’s BIO-GENESIS?

• All living things come from other living All living things come from other living thingsthings

• Wasn’t always thought this way...Wasn’t always thought this way...

Old Schoolers:Old Schoolers: Spontaneous Generation Spontaneous Generation

• Living things arise from Living things arise from nonlivingnonliving thingsthings

• TRUE?TRUE?

• NO!!!NO!!!

• Disproven by:Disproven by:– RediRedi– SpallanzaniSpallanzani– PasteurPasteur

Redi’s ExptRedi’s Expt

Spallanzani’s ExptSpallanzani’s Expt

Pasteur’s ExptPasteur’s Expt

Let’s Review! Let’s Review!

Project Stuff due…Project Stuff due…

• Team Leaders—Team Leaders—– Collect your team’s work Collect your team’s work

• Mark them off your listMark them off your list• Turn list in to meTurn list in to me

– Make sure their name is on anything they turn Make sure their name is on anything they turn inin

• EVERYTHING must be emailed to me by EVERYTHING must be emailed to me by 5pm today5pm today– Exception: beach walkover stuff can be Exception: beach walkover stuff can be

turned in Friday.turned in Friday.

Want BioBucks?Want BioBucks?

• Want to put together the text and Want to put together the text and design for flyers and magnets?design for flyers and magnets?

• Need to make a couple different onesNeed to make a couple different ones

• See me at a break or end of classSee me at a break or end of class

14-2: Earth’s History14-2: Earth’s History

What was EARLY EARTH like?What was EARLY EARTH like?

• VERY different conditionsVERY different conditions

• Hypotheses, testsHypotheses, tests

So, So, HowHow OldOld is Earth? is Earth?

• ~4 billion years~4 billion years– Look at the wall!Look at the wall!

• How do we know?How do we know?

• Radiometric DatingRadiometric Dating

Radiometric Dating: Radiometric Dating: how’s it work?how’s it work?

• Radioactive isotopesRadioactive isotopes Each: Specific Each: Specific raterate of decay of decay

• Half-lifeHalf-life: : Time for ½ to decay to stable formTime for ½ to decay to stable form

• C-14 (radioactive) : C-12 (stable)C-14 (radioactive) : C-12 (stable)What are isotopes??What are isotopes??

• Half-life for C: Half-life for C: 5,730 years5,730 years

12.1 The Fossil Record

2. 2. Radiometric datingRadiometric dating• uses decay of unstable isotopesuses decay of unstable isotopes

• Isotopes (different number of neutrons) have specific “half-lives”Isotopes (different number of neutrons) have specific “half-lives”

• Estimates an Estimates an actual AGEactual AGE

neutrons protons

2 Ways to Age Fossils 2 Ways to Age Fossils

Use Carbon-14 to Use Carbon-14 to Age Things Age Things < 60,000 yrs old< 60,000 yrs old

12.1 The Fossil Record

A half-life is the amount of time it takes for half of the isotope to decay.

An Example...An Example...

So...where and how did So...where and how did LIFELIFE begin? begin?

• Three main ideas– Organic molecule hypotheses– Early cell structure hypotheses– RNA as early genetic material

I. Organic molecule hypothesesI. Organic molecule hypotheses

• Organic = ????Organic = ????

• Elements in planet, so, how Elements in planet, so, how organic? organic?

• FIRST--FIRST--

• Oparin & Haldane’s Hypothesis (1920s)Oparin & Haldane’s Hypothesis (1920s)– Early earth conditionsEarly earth conditions– Ammonia, H gas, water vapor, Ammonia, H gas, water vapor,

hydrocarbons (methane)hydrocarbons (methane)

What did they think happened?What did they think happened?

• High tempsHigh temps

• Gases combine Gases combine simple org cmpds simple org cmpds– Amino acidsAmino acids

• Earth cooled, water condensation Earth cooled, water condensation lakes, etc & AAs gather therelakes, etc & AAs gather there

• Lightning, UV catalyze chem rxnsLightning, UV catalyze chem rxns macromolecules (proteins)macromolecules (proteins)

• Didn’t do an expt....Didn’t do an expt....

Miller & Urey’s Miller & Urey’s ExptExpt

• (1953-based on (1953-based on Oparin & Haldane Oparin & Haldane Hyp)Hyp)

• Variety of organic Variety of organic cmpds produced!cmpds produced!

• Lots other Lots other researchers sinceresearchers since

• COCO22, O, O22 interfere interfere w/it...so, must not w/it...so, must not have been present, or have been present, or happened under happened under water.water.

Another OptionAnother Option

• Organic cmpds Organic cmpds came from came from meteoritesmeteorites

II. Early cell structure hypothesesII. Early cell structure hypothesesHow can you get cells from organic cmpds?How can you get cells from organic cmpds?

Cell-likeCell-like structures first! structures first!

2. Lipid membrane hypothesis:2. Lipid membrane hypothesis:– Cell-like, but Cell-like, but not cellsnot cells– MicrospheresMicrospheres

• proteinsproteins

– Coacervates Coacervates • Lipid, AA, sugar dropletsLipid, AA, sugar droplets

1. Iron-sulfide bubbles hypothesis1. Iron-sulfide bubbles hypothesis

III. RNA as early genetic materialIII. RNA as early genetic material

RibozymesRibozymes:: present today in present today in unicellular euk’sunicellular euk’s RNA that can catalyze RNA that can catalyze reactions... even their reactions... even their own replicationown replication

Let’s Review!

Opener: Sure Happy It’s...Dec. 17Opener: Sure Happy It’s...Dec. 17thth!!!!!!

REVIEW...Summarize each experiment:

Redi Spallanzani Pasteur

14-3: Origin of Life14-3: Origin of Life

The Origin of HeredityThe Origin of Heredity• Cells/life-forms must be able to replicate...WHY?Cells/life-forms must be able to replicate...WHY?

What’s a RIBOZYME?What’s a RIBOZYME?• RNA that catalyzes a chem rxnRNA that catalyzes a chem rxn• Also allows RNA to self-replicateAlso allows RNA to self-replicate

• ““the RNA world”the RNA world”

• ...evidence that THIS may have been the ...evidence that THIS may have been the 11stst genetic material! genetic material!

3 Major Inferences about Early Earth:3 Major Inferences about Early Earth:

• Little/no Oxygen gasLittle/no Oxygen gas• Organic molecules “food” in the envtOrganic molecules “food” in the envt• Oldest fossils of cells ~ bacterial size Oldest fossils of cells ~ bacterial size

• Anaerobic, heterotrophic prokaryotesAnaerobic, heterotrophic prokaryotes

Diversity of Life Led to Competition for Diversity of Life Led to Competition for food...who came next?food...who came next?

• AUTOTROPHS!AUTOTROPHS!• Likely chemoautotrophs...why?Likely chemoautotrophs...why?• Example—Example—

• Archaea-harsh envts Archaea-harsh envts

THEN came Photosynthesis: EvidenceTHEN came Photosynthesis: Evidence

1.1. FossilsFossils

• 3.5 bya (cyanobacteria appeared)3.5 bya (cyanobacteria appeared)

• Stromatolites Stromatolites

2. Chemical Traces: Oxygen2. Chemical Traces: Oxygen• Harmful to many unicellular Harmful to many unicellular

organismsorganisms• Some able to bind it...1st sign of Some able to bind it...1st sign of

aerobic respiration!aerobic respiration!• Built up in atmosphere (~bill yrs?)Built up in atmosphere (~bill yrs?)• OzoneOzone

The First ProkaryotesThe First Prokaryotes

ArchaeaArchaea BacteriaBacteria

EukaryotesEukaryotes

CyanobacteriaCyanobacteria

ChloroplastsChloroplastsMitochondriaMitochondria

First EukaryotesFirst Eukaryotes• What are differences b/w pro. & eukaryotes?What are differences b/w pro. & eukaryotes?• May have developed from prokaryotes...May have developed from prokaryotes...• Draw it!Draw it!

Endosymbiotic TheoryEndosymbiotic Theory

• MutualisticMutualistic

• EVIDENCEEVIDENCE: :

• Chloroplasts & mitochondria replicate Chloroplasts & mitochondria replicate independently of cell cycleindependently of cell cycle

• Own DNA, sim to prok & circularOwn DNA, sim to prok & circular

http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60258.htm

REVIEW: REVIEW: True or False?True or False?

• The first cells must have been aerobic.The first cells must have been aerobic.• FalseFalse• RNA molecules are needed for protein synthesis.RNA molecules are needed for protein synthesis.• TrueTrue• Ozone in the upper atmosphere is poisonous to life.Ozone in the upper atmosphere is poisonous to life.• FalseFalse

REVIEW:REVIEW:• How’s RNA different from DNA?How’s RNA different from DNA?• RNA diff shapes; some self-replicatingRNA diff shapes; some self-replicating• What traits make archaebacteria likely relatives of What traits make archaebacteria likely relatives of

Earth’s earliest organisms?Earth’s earliest organisms?• Survive harsh envts, many anaerobic, chemoautotrophsSurvive harsh envts, many anaerobic, chemoautotrophs• Difference between photosynthesis & chemosynthesis?Difference between photosynthesis & chemosynthesis?• Energy from inorganics vs lightEnergy from inorganics vs light• Explain the endosymbiotic theory.Explain the endosymbiotic theory.• Primitive prok engulfed smaller proks. Which evolved Primitive prok engulfed smaller proks. Which evolved

into mitochondria and chloroplasts into mitochondria and chloroplasts

History of the Earth Video ClipHistory of the Earth Video Clip