Carbon And The Molecular Diversity Of Life

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Carbon And The Molecular Diversity Of Life

• Chapter 4

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Vitalism vs. Mechanism

• Vitalism is the belief that a life force exists
  outside of the jurisdiction of physical and
  chemical laws. Therefore, only living things can
  make chemicals found in living things.
• Mechanism is the belief that living things follow
  natural laws, and chemical in living things can
  be made in the laboratory.
• Laboratory synthesis of urea and acetic acid
  helped disprove the Vitalist beliefs.

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Stanley Miller Re-Creates Life, 1953
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Millers Experiment

• Stanley Miller, University of Chicago, 1953.
• Tests the abiotic synthesis of organic compounds
  by simulating what he thought were the conditions
  on Earth before life formed.
• Primitive atmosphere containing H2O, NH3, CH4,
  H2 (NO OXYGEN)
• Energy sources were heat and electric sparks

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Millers Results

• Spontaneous formation of organic compounds was
  possible.
• Various organic compounds including many amino
  acids were produced in his experiment.
• Showed the possibility that life could have
  formed, abiotically, on the primitive Earth.

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Life Based on Carbon

• Electronic configuration 1s22s22p2
• Electron promotion pushes one electron out of the
  2s orbital, up into the 2p orbitals
• The new configuration is
  1s2 2s12px12py12pz1 Four half-filled orbitals
  are now available for bonding
• Carbon will form four covalent bonds due to sp3
  hybridization

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Other Important Elements

• Hydrogen One covalent bond
• Oxygen Two covalent bonds
• Sulfur Two covalent bonds
• Nitrogen Three covalent bonds
• Phosphorus Three covalent bonds
• Bonds may be single or double for elements
  capable of making more than one bond with another
  element like carbon

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Structural IsomersMolecules that have the same
chemical formula but different structure
C4H10
Butane
Isobutane
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Geometric Isomers Isomers due to different
arrangements about a double-bond
Cis configuration
Trans configuration
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Enantiomers Optical Isomers

• Non-superimposeable, mirror images.
• Four different groups around a single carbon atom
  forms an asymmetric center

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Functional Groups

• Component part of an organic molecule commonly
  involved in chemical rxns
• May be non-polar, polar, or charged or
• Seven common functional groups
• Hydroxyl (Alcohol) OH
• Carbonyl O
• Carboxyl C00H (ionized at body pH)
• Amino NH2
• Sulfhydryl SH
• Phosphate PO42- (ionized at body pH)
• Methyl CH4 (Non-polar and hydrophobic)

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Hydroxyl Group
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Carbonyl Group
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Carboxyl Group
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Amino Group
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Sulfhydryl
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Phosphate Group
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Methyl Group
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