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Carbon and the Molecular
Diversity of Life
Chapter 4
Campbell and Reece 6th Edition
Organic Chemistry
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The study of organic compounds is called organic chemistry.
A cell is composed primarily of:
– 70-95% H2O
– C,N,O,S,P
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A Swedish chemist in the 19th century Jons Jakob Brazelius was the first to
notice that organic compounds are found in living organisms and inorganic
substances are found in the non-living.
Scientists believed that is was impossible to make complex organic
compounds from inorganic compounds.
– Vitalism – the idea that the life force was governed by something other that
chemical and physical laws.
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In 1828 a German chemist Fredrich Wohler attempted to make an
inorganic salt called ammonium cyanate from inorganic substances but
instead made urea which is present in animal urine.
Other scientists were not convinced because he extracted the cyanate from
living tissue.
Eventually Hermann Kolbe, a student of Wohler’s was able to make acetic
acid from strictly inorganic substances.
Stanley Miller


In 1953 Miller used a
laboratory simulation to
create primitive Earth.
Produced organic
molecules in the
laboratory using gases
present in the primordial
atmosphere like

NH3, H2O, H2 and CH4 and
electricity which simulated
lightning.
CARBON
• Carbon is very versatile because has a 4 valence
electrons.
• It has a tendency to created complex branched
molecules.
• Contributes to the diversity of organic compounds.
• Hydrocarbons are:
– composed of hydrogen and carbon.
– excellent fuels because the covalent bond between the
carbon and hydrogen contain a lot of energy.
– composed of partially decomposed organisms.
– Hydrophobic because they are long chains of carbon bound to
hydrogen atoms.
Carbon to form many different
chemical compounds:
• 1). Length of the carbon skeleton may
differ ( C-C, C-C-C, C-C-C-C-C, etc.).
2). Branching of the carbon skeleton
• ( C-C-C-C, C-C-C-C-C )
|
C
3). The number of double bonds may
differ
( C=C-C-C, C=C=C-C ).
4). The molecular structure may be
in ring form.
Isomer - A chemical compound
with the same molecular formula
but a different structural formula.
Parts of Hydrocarbons are Found
in Living Organisms
Organic Valences
Types of Isomers
• Structural
– Same molecular formula but different shape.
• Geometric
– Involves a double bond in which the groups of
atoms that are covalently bound to the carbon
backbone have a different spatial arrangement.
• Rhodopsin is a light induced isomer involved in vision.
• Enantiomers
– Mirror images of each other
• Thalidimide, L-Dopa and D-Dopa
Isomers
Functional Groups
• Molecular groups attached to the carbon
skeleton affect the function of the
molecule.
– Hydroxyl
– Carbonyl
– Carboxyl
– Amino
– Sulfhydryl (Thiol)
– Phosphate
Estrogen Versus Testosterone a
Subtle Difference in Function
Groups
Estrogen and Testosterone