Chapter 2: The Atoms and Molecules of Ancient Earth

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Chapter 2 The Atoms and Molecules of Ancient
Earth

• (Section 2.4 Redox reactions and the importance
  of Carbon)

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Objectives

• Understand and explain redox reactions
• Understand what happens to Carbon as it is
  reduced
• Be able to explain the importance of Carbon
• Be familiar with the various functional groups
  that diversify Carbon chains

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Oxidation-Reduction Reactionsoil rig

• Oxidation reactions result in a loss of electrons
• Oxidation may also occur through the addition of
  oxygen (more electronegative) to a molecule

• Reduction reactions result in a gain of electrons
• Reduction may also occur through the addition of
  hydrogen (less electronegative) to a molecule

Electron orbital position is the key when
electrons move to closer orbitals they lose
potential energy, -?G
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Oxidation-Reduction Reactionsoil rig
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What about Carbon?

• Almost all molecules associated with life contain
  Carbon
• The structure of a Carbon atom allows it to form
  up to four atomic bonds
• The electronegativity of Carbon is such that
  carbon can form either polar or nonpolar atomic
  bonds

• Reduced forms of Carbon-based molecules are
  believed to have utilized energy to structurally
  undergo change to form the four types of organic
  molecules that living things make proteins,
  nucleic acids, carbohydrates and lipids

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Functional GroupsGroups of Atoms Frequently
Attached to the Carbon Skeletons of Organic
Molecules

• Amino group -NH2
• Amines
• Act as base
• Carbonyl CO
• aldehyde at end of carbon chain
• ketone nested inside carbon chain
• Carboxyl -COOH
• form H

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Functional Groups

• Hydroxyl group -OH
• Polar
• Alcohols
• Phosphate -PO42-
• Usually very reactive
• ATP
• Sulfhydryl -SH
• Important for protein stabilization
• Thiols