Today we will start with…UNIT 1 History of life on earth! Big picture biodiversity-Major lineages, Evolution of Meiosis •  The early life and the Diversification of Prokaryotes (Ch24) •  Origin and Diversification of Eukaryotes (Ch25) •  Broad Patterns of Evolution (Ch23) •  Meiosis and Sexual Life Cycles (Ch 10) March 7th WED-EXAM! (11 days of class away…) So it is almost like every class is worth 10% of your exam grade.

A. The early life and the Diversification of Prokaryotes (Ch24)

How and when did earth form?

Age of earth and solar system….

4.5-4.6 Billion or Million?

(radio-isotopic dating of meteorites)

How did earth form?http://channel.nationalgeographic.com/videos/the-birth-of-earth/

Over time… collisions decreased in frequency and intensity the crust cooled, solidified and water accumulated on surface.

Some solid crust by about 4 bya

(some rocks in Canada are 3.96 billion years old).

Surface water by about 3.8 bya

(sedimentary rocks of that age in Greenland)

Early earth conditions? Dangerous, hot…

This is not a geology class…what are we interested in?

Life!

In groups of 3 think about..

•  Do we need a definition of life? Why?•  How should we define life?•  What would we look for if we wanted to claim

something we found on Mars was alive?•  Look over the slips of paper. How do your

definition/s “stand up”? Can your definition distinguish between the living (green pieces of paper) and non-living items (purple pieces of paper)? (see next slide)

•  What problems do you see?

https://nabt.org/files/galleries/ABT_Online_Jan_2013.pdf

•Polarbear•Tyrannosaurusrex(theanimal,notthefossil!)•Homosapiens•Cancercell•Nudibranch(seaslug)•Lichen•Seaweed•Palmtree•Seedlessorangetree•E.coli•Diatom•Gene@callymodifiedcornplantgrowinginafield•Syphilisbacteria•Giardia•Redbloodcell(thesecellshavenoDNAandcannotreplicate)•Mule(infer@leoffspringofamaledonkeyandfemalehorse)•Workerbees(sterilecaste)•Yeast•Bedbugs•Humanspermcell•Infer@lehumancouple•Humanwithsuicidalthoughts•Frozenfrog(in“hiberna@on”–allprocesseshalted)•Mycoplasmagenitalium(mustliveinsideahumancell;otherwiseitdies)•Chlamydiabacteria

•Atomicbomb•Soapbubbles•Taxidermiedmoosehead•Frostonawindow•Lava•Star•Car•Fire•Compass•Smartphone•Crystals•Deadtree•Cloud•Lake•Petrifiedwood•Snowflake•Salt•Cannedtuna•Spam•Computervirus•All-Brancereal•Tornado•Hurricane•Lightning•Clay•Prionprotein(proteinsthatcantriggerotherproteinstofoldimproperlylikethemselves)

Thesearethethingsthatwerehandedout-whydidtheychoosesomeofthese?

Definitions of life handout…which ones do you connect with? Which ones do you not really like? (Definitions on next slide-these were handed out in class on a piece of paper) “Thedefini@onscanbebroadlygroupedintothosethatfavorafocusonreproduc@on/evolu@on,metabolism,thermodynamics,thebiosphere(ecosystems),complexity,or“other.”Thedefini@onsuppliedforKenNealsonwasobtainedfrom“Classifica@onofLivingThings”(UniversityofCalifornia”

Defini8onsoflifeAnniePrud’homme-Généreux,TheAmericanBiologyTeacher,Vol.75,No.1,pages53–57.Thiscollec@oncontainssomeoftheproposeddefini@onsoflifebuttherearemanymore.Forexample…consultLahav(1999),McKay(2004),orHazen(2006)foraddi@onalideas.Bedau&Packard(1991)Weproposeto[…]viewlifefromamoreglobal,sta@s@calperspec@ve.Nosinglemoleculeofgashasamacroscopicpropertyliketemperature;temperatureismeaningfulonlyforalargepopula@onofmolecules.Similarly,nosingleorganismexhibitsindefinitelyongoinglife[…].Fromaglobalperspec@ve,onlythecomplexwebofinterac@ngorganisms–theen@rebiosphere–remains“alive”inthelongrun,throughthecon@nualcycleofbirthanddeathofindividualorganisms.[…]Anorganismisaliveonlyifitisamemberofanac@velyevolvingbiosphere.Harold(2001)Lifeisfirstandforemostamicrobialphenomenon.[…]Livingthingsdisplaycomplexorganiza@on[…]theycarryoutmetabolism(energygenera@oninpar@cular)reproducetheirownkinds,andhavefunc@onalpartsadaptedtotheirenvironment.[…]Lifeisaqualityoranributeofen@@esthatmeetthecriteria.Theycomeinavastrangeofshapesandsizes,fromEscherichiacolitothebluewhale,buttheminimalunitsthatmeetallthecriteriaaremicrobialcells,bothprokaryo@candeukaryo@c.

Defini8onsoflifeAnniePrud’homme-Généreux,TheAmericanBiologyTeacher,Vol.75,No.1,pages53–57.Thiscollec@oncontainssomeoftheproposeddefini@onsoflifebuttherearemanymore.Forexample…consultLahav(1999),McKay(2004),orHazen(2006)foraddi@onalideas.Bedau&Packard(1991)Weproposeto[…]viewlifefromamoreglobal,sta@s@calperspec@ve.Nosinglemoleculeofgashasamacroscopicpropertyliketemperature;temperatureismeaningfulonlyforalargepopula@onofmolecules.Similarly,nosingleorganismexhibitsindefinitelyongoinglife[…].Fromaglobalperspec@ve,onlythecomplexwebofinterac@ngorganisms–theen@rebiosphere–remains“alive”inthelongrun,throughthecon@nualcycleofbirthanddeathofindividualorganisms.[…]Anorganismisaliveonlyifitisamemberofanac@velyevolvingbiosphere.Harold(2001)Lifeisfirstandforemostamicrobialphenomenon.[…]Livingthingsdisplaycomplexorganiza@on[…]theycarryoutmetabolism(energygenera@oninpar@cular)reproducetheirownkinds,andhavefunc@onalpartsadaptedtotheirenvironment.[…]Lifeisaqualityoranributeofen@@esthatmeetthecriteria.Theycomeinavastrangeofshapesandsizes,fromEscherichiacolitothebluewhale,buttheminimalunitsthatmeetallthecriteriaaremicrobialcells,bothprokaryo@candeukaryo@c.

Joyce(1995)Lifeisaself-sustainedchemicalsystemcapableofundergoingDarwinianevolu@on.[Defini@onadoptedbyNASA]KauffmanLifeisanexpectedcollec@velyself-organizedpropertyofcataly@cpolymers.Korzeniewski(2001)Life[…]isdefinedasanetworkofinferiornega@vefeedbacks(regulatorymechanisms[intheserviceofsustainingtheiden@tyoftheindividual–anydevia@onfromsomeparametersetsinmo@onaseriesofstepstogetbacktothedefaultvalue,likeathermostat])subordinatedto(beingatserviceof)asuperiorposi@vefeedback(poten@alofexpansion[i.e.replica@on]).Koshland(2002)Therearesevenpillarsoflife:aProgram(anorganizedplan),Improvisa@on(awaytochangetheprogram),Compartmentaliza@on(ameansofsepara@ngselffromtheoutsideworld),Energy(tofuelchemicalreac@ons),Regenera@on(torepairandreplaceitself),Adaptability(torespondtotheenvironment),andSeclusion(toinsulatechemicalreac@onsfromoneanother).

LangtonLifeisapropertyofform,notmaner,aresultoftheorganiza@onofmanerratherthansomethingthatinheresinthemaneritself.Neithernucleo@desnoraminoacidsnoranyothercarbon-chainmoleculeisalive–yetputthemtogetherintherightway,andthedynamicbehaviourthatemergesoutoftheirinterac@onsiswhatwecalllife.Itiseffects,notthings,uponwhichlifeisbased–lifeisakindofbehavior,notakindofstuff–andassuchitiscons@tutedofsimplerbehaviors,notsimplerstuff.Margulis&Sagan(2000)Livingorganismsareautopoie@csystems.[Inotherwords,theymakemoreofthemselves]McKay(1991)Lifeisamaterialsystemthatundergoesreproduc@on,muta@on,andnaturalselec@on.Morales(1998)Livingthingsaresystemsthattendtorespondtochangesintheirenvironment,andinsidethemselves,insuchawayastopromotetheirowncon@nua@on.NealsonLifecanberecognizedbywhatitdoes:livingorganismscreatehallmarkmoleculesandcreatechemicaldisequilibrium.Pace(2001)Lifeisaself-replica@ng,evolvingsystembasedonorganicchemistry.Trifonov(2011)Lifeisself-reproduc@onwithvaria@ons.[Trifanoviden@fiedthecommonali@esin150defini@onsoflifetogettothisidea]

A slightly different focus….What steps do you need to get the evolution of life?

Connects to your text more closely…

What steps do you need to get evolution of life? P459

1.  Small organic molecules (like amino acids)

2.  Joining of these into longer macromolecules (like proteins, nucleic acids)

3.  A packaging of some sort-Why?

4.  Self replication

Anything you would like to add to this list?

1.  Small Organic Molecules like amino acids?

Miller and Urey

Others argue atmosphere was different…still get organic molecules

Meteorites! (one in Australia had 80 amino acids)

Atmosphere=Hydrogen Methane and Ammonia

2. Assembly of these amino acids building blocks into polymers

Now we need to get them together into proteins and nucleic acids

Drip solutions onto hot rocks or clay yields evaporation borders encourage polymerization (hooking together)

or Ice!

Miller and Bada

As ice crystal forms only molecules of water join the growing crystal, while impurities like salt or cyanide are excluded.

Impurities become crowded in microscopic pockets of liquid within the ice, and this crowding causes the molecules to collide more often.

Chemically speaking, it transforms a tepid seventh-grade school dance into a raging molecular mosh pit. http://discovermagazine.com/2008/feb/

3. Packaging-Acquire cellular form

Membranes often form spontaneously under certain circumstances-vesicles

Hydrophobic molecules in a mixture organize into a bilayer at the surface of droplets like the lipid bilayer that is the outside of cell !

4. Self replicating polymers

RNA world

RNA can make proteins and can behave like an enzyme

DNA evolved later (?) as a safe deposit for genetic info-more stable

5. Metabolism-energy capture system…(could add)

So what evidence do we see for early life?

Fossils vs “chemical fingerprints” vs GeneticAnd When?

Oldest fossils of ProkaryotesStromatolites (3.5 bya) p461Made of Cyanobacteria (a kind of photosynthetic bacteria) Stromatolite relatives still exist in Western AustraliaAnd are fossils in Northern MN!https://www.lakesuperior.com/the-lake/natural-world/192feature/

Chemical fingerprints-Carbon Isotope

(Harrison, Manning and Mojzis)

Greenland rocks again!

Those rocks have been heated and squished so unlikely to see fossils but…

Look at carbon isotope ratios and can detect presence of life..from…3.8 Billion

“The carbon aggregates in the rocks have a ratio of about 100-to-one of Carbon 12 (the most common isotope form of carbon, containing six protons and six neutrons) to C 13 (a rarer isotopic form of carbon, containing six protons and seven neutrons). The light carbon, Carbon 12, is more than 3 percent more abundant than scientists would expect to find if life were not present, and 3 percent is very significant……..”http://www.sciencedaily.com/releases/2006/07/060721090947.htm

Take away point…

Basically life concentrates the light form (Carbon 12)The more common isotope (Carbon 12) is EVEN MORE common in living organisms.

But..latest news another fossil!http://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html?_r=0

Remember those sedimentary rocks in Greenland..

Researchers “argue that life must therefore have originated even earlier, probably in the late Hadean stage of Earth’s history, which lasted from 4.65 billion years ago — when the planet formed from debris in orbit around the sun — to 4 billion years ago. But the Hadean was so called because of the hellish conditions thought to have prevailed, including cataclysmic meteorite impacts that boiled the oceans into steam and turned Earth’s surface into molten lava. The largest of these impacts, at 4.5 billion years ago, tore a piece from Earth that became the moon.”.

Genetic evidence? Does not give us a date but what characteristics might the first life have had? http://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html

“Genes are adapted to an organism’s environment. So Dr. Martin hoped that by pinpointing the genes likely to have been present in LUCA, he would also get a glimpse of where and how LUCA lived. “I was flabbergasted at the result, I couldn’t believe it,” he said. The 355 genes pointed quite precisely to an organism that lived in the conditions found in deep sea vents, the gassy, metal-laden, intensely hot plumes caused by seawater interacting with magma erupting through the ocean floor.”

Where??Surface ponds-Primordial soup-Surface dangerous!

Why?

Deep sea vents- Interesting amino acids form there

The worst impacts would have been 10-100 million years apart and bacteria could have survived at the bottom of the oceans…

Other planets?

Panspermia hypothesis…

Europa (moon of JUPITER) water and active volcanoes -hydrothermal vents in liquid ocean capped by ice??

Mars-today is cold and dry but had liquid water and it may have had an atmosphere that warmed it…

What else do we know?

We do find large spherical organic molecules called fullerenes at meteor impact sites (as well as a.a.-we pointed this out before)

Bacteria can survive outer space!

This could be a problem….http://www.sciencemag.org/news/2017/03/uv-light-could-easily-kill-microbial-stowaways-mars

FYI…I did not show this in class but fun stuff.Time magazine description of an article in “PLOS”

There are…about 20 billion Earths in our galaxy alone. That in turn means that an Earth-like world is likely to be just 12 light-years away, and that its parent star is visible to the naked eye.

Read more: 20 Billion Earths in the Milky Way Alone? | TIME.com

http://science.time.com/2013/11/04/so-much-for-earth-being-special-there-could-be-20-billion-just-like-it/#ixzz2mKVgqMRv �