Where did all this come from?

Transcription

1 Where did all this come from? BIG BANG makes Hydrogen (H2), Helium (He) Ammonia (NH3) Formaldehyde (H2CO) Hydrogen Cyanide (HCN) Methane (CH4) or Carbon dioxide (CO2) 2(H2CO) + (HCN) -> Glycolaldehyde

2 From Aristotle: To Reni: To Darwin:

3 From Aristotle: To Reni: To Darwin: spontaneous generation happens, often life comes from life observed similarities in life forms, but also unique attributes suited to particular environments. hypothesized similarity and diversity was due to descent from common ancestor plus natural selection from one species, to many

4 Are these similarities because of descent from a common ancestor?

5 Proceed with CAUTION when inferring descent from a common ancestor based on similarity Is similarity coincidental? Or because of functional constraints?

6 Is similarity coincidental? Or because of functional constraints? Pick a number between 1 and 5

7 Is similarity coincidental? Or because of functional constraints? Sometimes one particular way is the only way it works well: Other times, there are many ways to do something and they work equally well:

8 Are these similarities coincidental or functional?

9 Are these similarities coincidental or functional? (if not, then similarities suggest they are related by a common designer!) Pyramid of Khafre, Egypt ca 2550 BC Mayan pyramids of Teotihuacan, Mexico

10 there is a functional reason for similarities one way works best Pyramid of Khafre, Egypt ca 2550 BC Mayan pyramids of Teotihuacan, Mexico Black Pyramid of Amenemhat III, Egypt BC Fajada Butte, New Mexico

11 So how would you go about demonstrating that humans are related to: monkeys mice cows whales dogs

12 So how would you go about demonstrating that humans are related to: monkeys mice cows whales dogs C = pelvis and femur

13 How far can we extrapolate from one species to many?

14 Darwin hypothesized all life descended from a single common ancestor, but he lacked evidence to support his hypothesis. If Darwin s hypothesis was true what evidence would you expect to find?

15 Similarities that are shared (but are not coincidental or functional) suggest descent from a common ancestor Most lifeforms* are made of cells constructed of similar biomolecules Further, the cells of eukaryotes (animals, plants and amoeba) are similar (have nucleus, mitochondria, etc) (*Archaea and viruses are a bit unusual)

16 Similarities that are shared (but are not coincidental or functional) suggest descent from a common ancestor All life uses proteins made from the same 20 amino acids

17 All life uses proteins made from the same 20 amino acids and we know there are other amino acids

18 Are these similarities coincidental, or functional? or because of descent from a common ancestor? All life uses DNA to encode those proteins (and all life uses the same 4 nucleotides to do so)

19 Are these similarities coincidental, or functional? or because of descent from a common ancestor? All life is built on the same Central Dogma of Modern Biology T A G T C A A T A G T C G C G DNA RNA C U A C A U A G C A U Amino acid G Amino acid protein Amino acid

20 All modern life on Earth is related by descent from a common ancestor. What evidence supports this? Same central dogma Same 4 nucleotides in DNA Same 20 amino acids in protein Same Universal Codon Decoder

21 So all modern life can be reduced to the central dogma

22 But we have a chicken or the egg problem: Proteins are made from DNA, but DNA is made by proteins. This lead to a hypothesis that life must have originated in a singlebiopolymer capable of doing both genetic storage and catalysis.

23 But we have a chicken or the egg problem: Which polymer came first? DNA is bad choice because the properties that make DNA suitable for being copied make it bad for folding into complex shapes. Protein is bad choice because the properties that makes protein suitable for folding into complex shapes make it bad for being copied. There are contradictory chemical demands between being a good template for storing information, and being a good catalyst.

24 But we have a chicken or the egg problem: Is there a biomolecule can do both: 1. store information and be copied accurately (like DNA) 2. fold into structures that catalyze chemical reactions (like proteins)

25 The RNA world hypothesis RNA

26 RNA The RNA world hypothesis If life started with only RNA, then we should look for evidence Is there any evidence that RNA can act as a catalyst like enzymes? Are there any vestigial traces from the RNA world places where RNA is used but it doesn t make sense?

27 RNA can do both catalysis and genetics Ribosome: Small ribosomal subunit: RNA in color, ribosomal proteins in white.

28 Why use RNA as an intermediate between DNA and protein? RNA seems inferior to DNA: 2 OH makes RNA unstable U is promiscuous H-bonding partner C degrades into U, so RNA is impossible to proofread: RNA: CUCU -> UUUU DNA: CTCT -> UTUT

29 Why use RNA as an intermediate between DNA and protein? RNA seems inferior to DNA: 2 OH makes RNA unstable U is promiscuous H-bonding partner C degrades into U, so RNA is impossible to proofread: RNA: CUCU -> UUUU DNA: CTCT -> UTUT RNA in Central Dogma is vestigial traits DNA is made from RNA with a protein T is made from U with a protein (so RNA must have come first, then proteins, then DNA)

30 RNA in vitamins are vestigial traits RNA is part of vitamins and cofactors common to all life: Vitamin B-12, FAD, NAD, CoA, ATP, SAM, ribo-terpene, etc Nicotinamide Adenine Dinucleotide (NAD) Made from niacin (Vitamin B3)

31 RNA But there is still a big gap between the RNA world and the Big Bang Ammonia (NH3) Formaldehyde (H2CO) Hydrogen Cyanide (HCN) Methane (CH4) or Carbon dioxide (CO2) 2(H2CO) + (HCN) -> Glycolaldehyde

32 Stanley Miller s Prebiotic Soup Mix methane, ammonia, water, hydrogen gases plus energy (electric spark) Creates organic molecules, mostly amino acids (similar experiments have yielded nucleic acids)

33 RNA Random RNA polymers Ammonia (NH3) Formaldehyde (H2CO) Hydrogen Cyanide (HCN) Methane (CH4) or Carbon dioxide (CO2) 2(H2CO) + (HCN) -> Glycolaldehyde

34 A random bunch of polymers AXZ RHIKS ELLJ ASDGJA SODFMA JKSDOF GASD SDGAJKDR JLERTSSDD SKA DGOASNM HKR LJKOSM HKODMJ SAK DFGIAS DFJA ONCE UPON A TIME SA DJFO AJASDJ OASD PHLQN KHJAID ASVMAEW OIHASJA LKASDOJO KSDOAFKJ SKDFAO IN A GALAXY FAR FAR AWAY

35 A random bunch of polymers AXZ RHIKS ELLJ ASDGJA SODFMA JKSDOF GASD SDGAJKDR JLERTSSDD SKA DGOASNM HKR LJKOSM HKODMJ SAK DFGIAS DFJA ONCE UPON A TIME SA DJFO AJASDJ OASD PHLQN KHJAID ASVMAEW OIHASJA LKASDOJO KSDOAFKJ SKDFAO IN A GALAXY FAR FAR AWAY