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AGA 0316 Aula 11 Sigam o Carbono -1. 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

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AGA 0316 Aula 11Sigam o Carbono -1


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


FOLLOW THE LIFE

  • Follow the water

  • Follow the carbon

  • Follow the nitrogen

  • Follow the energy

  • Follow the entropy

  • Follow the information


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).


Como as biomoléculas são encontradas?

IR-Telescopes (vibrational lines)

Radiotelescopes (rotational lines)

VLA

Itapetinga, SP


Onde são encontradas as biomoléculas?

Key hole Nebula

Gaseous Pillars – Eagle Nebula

Titan

Hale-Bopp

Murchinson





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.


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


Chemical bonds

  • Covalent

  • Ionic

  • Hydrogen



ethene

benzene

ethanol

fullerene

diamond


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.


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/


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


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


Inorganic carbon

(C-O bonds only)

Organic carbon

(has C-H and C-C bonds)


Coal

Oil

JENNY HAGER/ THE IMAGE WORKS

http://www.nationalfuelgas.com

Organic

carbon

http://www.upl.cs.wisc.edu/~stroker/jungle.jpg


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/


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


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)


Glucose

Fructose

Table sugar


Glucose polymerization

H2O

Linked by dehydration reaction

Polysaccharides

In starch molecule (potato) there can be 100s thousands of glucose units


Lipids (fats and oils)

  • Representatives: fatty acids and cholesterol

  • Poorly soluble

  • Good (concentrated)

    energy source

  • Flexible

    (cell membrane material)


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


L-Alanine

Glycine

Linked by dehydration reaction


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


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?


Biology uses only

left-handed Alanine




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.


Large carbonaceous molecules in space

Diamond <<

Fullerenes ~ 0.5 %

Graphite ?

PAHs ~ 15 %

C-chains ~ 0.1%

> 50% ??

C-onions

Soot

Nanotubes

Ehrenfreund & Charnley 2000


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%


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:


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


2º TRABALHO DE AGA 0316 meteorite

Fazer resenha sobre o artigo:

“Finding a second sample of life on Earth”,

de Davies & Lineweaver

www.astro.iag.usp.br/~janot/


QUESTÕES SOBRE A AULA 11 meteorite

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?


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