AGA 0316 Aula 11 Sigam o Carbono -1

1. AGA 0316 Aula 11Sigam o Carbono -1

2. RÁPIDO BALANÇO DA MATÉRIA ATÉ AQUI • O que é a Astrobiologia? • O que é vida? Quaestão Bio • O Universo – condições Astro • Complexidade • Complexidade & Princípio Antrópico • Evolução da vida na Terra:em 4 milhões de anos, cérebro humano passa de 0,5 a 1,4 kg! • O satélite CoRoT: busca por exoplanetas (Brasil) • Buscando a vida: a) busque a água! Planetas... • b) Busque a água: a atmosfera terrestre • c) Busque o carbono + astroquímica-astrobio

3. FOLLOW THE LIFE • Follow the water • Follow the carbon • Follow the nitrogen • Follow the energy • Follow the entropy • Follow the information 

4. Universo Orgânico! • 0.5 % da matéria bariônica “visível” está na forma molecular. (Fraser, McCoustra & Willians, 2002, A&G, 43, 2.11). • > 150 Moléculas detectadas no espaço (~50% orgânicas: CHON).

5. Como as biomoléculas são encontradas? IR-Telescopes (vibrational lines) Radiotelescopes (rotational lines) VLA Itapetinga, SP

6. Onde são encontradas as biomoléculas? Key hole Nebula Gaseous Pillars – Eagle Nebula Titan Hale-Bopp Murchinson

7. 151 interstellar and circumstellar molecules H2 C6H6 NH3 CO

8. Carbon in human body

9. Carbon in the Universe 2.3

11. Why Carbon? • Carbon atom can form up to 4 chemical bonds with many other atoms – can form long and complex molecules • Carbon can form compounds that readily dissolve in water.

12. Hydrogen Outer shell/orbits Typically only electrons from the outer shell (valent electrons) engage in chemical bonds Carbon There is an “optimal” number of electrons per shell. S-shell = 2 electrons P-shell = 8 electrons S-shell P-shell Helium

13. Chemical bonds • Covalent • Ionic • Hydrogen

14. Carbon has 4 valent electrons – can form up to 4 bonds Methane Ethane

15. ethene benzene ethanol fullerene diamond

16. Polymerization • A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalentchemical bonds. Well known examples of polymers include plastics and DNA.

17. 2º TRABALHO DE AGA 0316 Fazer resenha sobre o artigos: “Finding a second sample of life on Earth”, de Davies & Lineweaver www.astro.iag.usp.br/~janot/

18. Silicon life? • Si is abundant and also can form four bonds at once (like C). But! • Si bonds are much weaker – complex molecules based on Si will be fragile • Si does not form double bonds – less variety

19. Organic and Inorganic Carbon C can be in reduced or oxidized forms. Organic carbonInorganic carbon (reduced)(oxidized) ‘CH2O’ CO2carbon dioxide H2CO3carbonic acid Example: HCO3bicarbonate ion Glucose -- C6H12O6CO3= carbonate ion

20. Inorganic carbon (C-O bonds only) Organic carbon (has C-H and C-C bonds)

21. Coal Oil JENNY HAGER/ THE IMAGE WORKS http://www.nationalfuelgas.com Organic carbon http://www.upl.cs.wisc.edu/~stroker/jungle.jpg

22. Inorganic carbon Seashells http://www.cmas-md.org/Images/Sanjay/UnivTop4.jpg Coral http://www.summerclouds.com/Vero/Sea%20Shells.jpg http://educate.si.edu/lessons/currkits/ocean/

23. Four types of organic macromoleculesin living systems. Most of the molecules in the living systems are water (H2O) and large organic macromolecules: • Carbohydrates • Lipids • Proteins • Nucleic Acids

24. Carbohydrates (sugars, starches) • Representatives: Glucose, Fructose • Many hydroxyl groups (-OH) • Soluble in water • Form Polysaccharides • Good energy source • Structural support for organisms (cellulose - the main constituent of wood)

25. Glucose Fructose Table sugar

26. Glucose polymerization H2O Linked by dehydration reaction Polysaccharides In starch molecule (potato) there can be 100s thousands of glucose units

27. Lipids (fats and oils) • Representatives: fatty acids and cholesterol • Poorly soluble • Good (concentrated) energy source • Flexible (cell membrane material)

29. Proteins • “Proteios” – primary • Long “trains” of amino acids • Different proteins have different sequence of amino acids • 20 amino acids used in any organism • Some provide structure (fingernails, hair) • Some serve as catalysts • Enzymes – proteins with catalitic properties

30. L-Alanine Glycine Linked by dehydration reaction

31. Catalysts in Chemistry • Suppose chemical reaction: A + B  AB is a slow reaction • The same reaction can be accelerated with catalyst (D): A + D  AD fast step B + AD  AB + D fast step The net result is still: A + B  AB but it is much faster

32. Proteins (continued) • Even though there are ~70 amino acids any known life uses only 20 • Amino acids derived abiotically are a mix of both “left-handed” and “right-handed” ones. Biological amino acids are only left-handed. Chirality • Was there a common ancestor for all life?

33. Biology uses only left-handed Alanine

34. Qual a Origem do Carbono?

35. Credit: Y.Pendleton

36. Nebulosas Planetárias • O Sol vai morrer assim • Estrelas com massas menores que 8 vezes a massa do Sol • Núcleo anã branca • Camadas exteriores nebulosa planetária • C, N • Tempos: até varios Ganos • Promovem as condições pré-bióticas.

38. Large carbonaceous molecules in space Diamond << Fullerenes ~ 0.5 % Graphite ? PAHs ~ 15 % C-chains ~ 0.1% > 50% ?? C-onions Soot Nanotubes Ehrenfreund & Charnley 2000

40. Meteorites • A meteorite is a natural object originating in outer space that survives an impact with the Earth's surface without being destroyed. • Chondrites – 86% (5% Carbonaceous Chondrites) • Achondrites – 8% • Iron meteorites – 5%

41. Meteorites represent the only extraterrestrial material which can be studied on Earth ! Insoluble C-fraction: 60-80 % aromatic carbon highly substituted small aromatic moieties branched by aliphatic chains Murchison (1969, Australia) Volatile fraction:

42. Abundances of soluble organic compounds in the Murchison meteorite(Botta & Bada 2002, Sephton 2002, 2004) Compound Class Concentration(ppm) Amino Acids CM 17-60 CI ~5 Aliphatic hydrocarbons >35 Aromatic hydrocarbons 3.3 Fullerenes > 1 Carboxylic acids > 300 Hydroxycarboxylic acids 15 Dicarboxylic acids & Hydroxydicarboxylic acids 14 Purines & Pyrimidines 1.3 Basic N-heterocycles 7 Amines 8 Amides linear > 70 cyclic > 2 Alcohols 11 Aldehydes & Ketones 27 Sulphonic acids 68 Phosphonic acids 2

43. 2º TRABALHO DE AGA 0316 Fazer resenha sobre o artigo: “Finding a second sample of life on Earth”, de Davies & Lineweaver www.astro.iag.usp.br/~janot/

44. QUESTÕES SOBRE A AULA 11 1) Onde há Carbono no Universo? 2) Porque o C e um elemento-chave para a vida? 3) Dê exemplos de compostos de C que encontramos habitualmente. 4) Porque a quiralidade é um elemento-chave para a descoberta de vida extraterrestre?