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Carbon and Organic Molecules

4.1 Organic chemistry is the study of carbon compounds

  • Organic compounds were once thought to arise only within living organisms, but this idea (vitalism) was disproved when chemists were able to synthesize organic compounds in the laboratory.

4.2 Carbon atoms can form diverse molecules by bonding to four other atoms

  • The Formation of Bonds with Carbon- A covalent-bonding capacity of four contributes to carbon’s ability to form diverse molecules.  Carbon can bond to a variety of atoms, including O, H, and N.  Carbon atoms can also bond t other carbons, forming the carbon skeletons of organic compounds.

  • Molecular Diversity Arising from Carbon Skeleton Variation- THe carbon skeletons of organic molecules vary in length and shape and have bonding sites for atoms of other elements.  Hydrocarbons consist only  of carbon and hydrogen.  Isomers are molecules with the same molecular formula but different structures and properties.  Three types of isomers are:
    *structural isomers:
    are molecules which have the same molecular formula but have different connections

    *geometric isomers:are molecules that are locked into their spatial positions with respect to one another due to a double bond or a ring structure

    are stereoisomers that are non-superimposable mirror images

4.3 Functional groups are the parts of molecules involved in chemical reactions

  • The Functional Groups Most Important in the Chemistry of Life- Functional groups are chemically reactive groups of atoms within an organic molecule that give the molecule distinctive chemical properties.  The hydroxyl group (-OH) is polar, thus helping compounds dissolve in water.  The carbonyl group (>CO) can be either at the end of a carbon skeleton (aldehyde) or within the skeleton (ketone).  The carboxyl group (-COOH) is found in carboxylic acids.  THe hydrogen of this group can dissociate, making such molecules acids.  The amino group (-NH2) can accept a proton (H+), thereby acting as a base.  The sulfhydryl group (-SH) helps stabilize the structure of some proteins.  The phosphate group (-OPO32-) has an important role in the transfer of energy.

  • ATP: An Important Source of Energy for Cellular Processes- When a phosphate group splits off from ATP, energy is released that can be used by the cell.

  • The Chemical Elements of Life: A Review- Living matter is made mostly of carbon, oxygen, hydrogen, and nitrogen, with some sulfur and phosphorus.  Biological diversity has its molecular basis in carbon’s ability to form a huge number of molecules with particular shapes and chemical properties.