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Crazy Carbon
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Chapter 4 notes
Save me from Organic
Chemistry!!!
 Carbon is
responsible
for the
large
diversity of
biological
molecules
Organic Molecules
 Compounds containing carbon
 These compounds can contain thousands of
atoms.
 Overall percentages of major elements
(C,H,O,N,S,P) are the same from one
organism to the next. Because Carbon is so
versatile, it can be used to build bzillions of
organic molecules.
 Variations in organic molecules distinguish
different species
History
 Jons Jakob Berzelius
 Made distinction between organic (found in
living organisms) and inorganic (found in
non living world).
 Gave rise to Vitalism – belief in a life force
outside of physical and chemical laws
History
 Friedrich Wohler
 Attempted to make inorganic compounds
 Actually made urea – a compound found in
urine (made without a living organism
involved)
 Started chipping away at theory of vitalism
History
 Stanley Miller
 Tested whether organic molecules could
arise spontaneously under conditions of
early earth
 Led to theory of mechanism – the view that
physical and chemical laws govern all
natural phenomena – including the
processes of life
Very Versatile Building
Blocks
Chemical Structure
 Carbon has 6 electrons, 2 in the first shell, 4 in
the outer shell.
 So....Valence of Carbon is 4 (tetravalence)
 It can bond to four other molecules
 Carbon completes its valence by sharing
electrons, forming covalent bonds (NOT ionic)
 Shape is a tetrahedron (109˚)
 Most frequent partners are O, H, and N
Simple Carbon Molecules
 CH4--Methane-4 single bonds,
tetrahedron shape
Simple Carbon Molecules
 CO2--Carbon Dioxide-source of Carbon
for all organic molecules found in
organisms (due to photosynthesis).
Chemical formula O=C=O
Complex Carbon Molecules
 Carbon can bond to other carbon
molecules forming long chains These are
the skeletons of organic molecules
 Carbon skeletons can be straight,
branched, or arranged in rings
Figure 4.4 Variations in carbon skeletons
Hydrocarbons
 Long chains containing only carbon and
hydrogen
 Major component of petroleum
 Not prevalent in living things, but some organic
molecules, like fat, have regions of
hydrocarbons.
 Hydrocarbons are hydrophobic because the
bonds are nonpolar.
 Store lots of energy (gas in a car, fat in animals)
Figure 4.5 The role of hydrocarbons in fats
Interesting Isomers
 Same molecular formula, but different
structure and different properties.
Structural Isomers
 Differ in covalent arrangement of their
atoms. The longer the carbon skeleton,
the more structural isomers.
 Location of double bonds can also differ
Geometric Isomers
 Same covalent partnership, different spatial
arrangements
 Result of inflexible double bonds (atoms
attached to a double bond can’t rotate freely)
 The different shapes affect biological activities.
ex. Vision involves light changing chemical
rhodopsin from one geometric isomer
to another.
Enantiomers
 Mirror images formed when carbon is attached
to four different atoms. The middle Carbon is
asymmetric!!
 Cells can distinguish enantiomers based on
their different shapes. One is “active” and the
other is “inactive”.
ex. Pharmaceuticals....sometimes drug
isomers produce no effect or harmful
effects on patients
Figure 4.7 The pharmacological importance of enantiomers
What
kind of
isomer
am I???
Functional Groups
 Components of organic molecules that are
most commonly involved in chemical reactions.
 Number and arrangement of functional groups
give molecules their unique properties.
 All are hydrophilic, so soluble in water
 Usually attached to a carbon on the skeleton
ex. Estradiol and Testosterone--have
same structural backbone, but different
functional groups that cause one to take
care of feminine qualities and other one
mighty maleness.
Hydroxyl -OH or -HO
 Organic compounds containing hydroxyl
groups are called ALCOHOLS
 Polar because O is really
electronegative!!! This attracts water
molecules and helps dissolve
ex. Sugars
Carbonyl > CO
 Carbon atom joined to oxygen by a double
bond
 Aldehydes: Carbonyl group on end of carbon
skeleton
 Ketones: Carbonyl group in the middle of the
skeleton
 Variations in location of carbonyl group is
source of molecular diversity
ex. Acetone (ketone) an Propanol
(aldehyde) are structural isomers with
different properties
Carboxyl -COOH
 Oxygen double bonded to carbon
that is also bonded to a hydroxyl (OH)
 Form carboxylic acids (organic
acids)
 Has acidic properties because it is
a source of H+ ions. Bond
between O and H is so polar that
hydrogen tends to dissociate.
ex. Acetic Acid (vinegar),
substance in ant stings
Amino -NH2
 Nitrogen atom bonded to two hydrogen atoms
and to carbon skeleton
 Compound with this group is called an amine
 Acts as a base because NH2 is able to pick up
H+ ions from the surrounding solution and
become NH3+. This lowers the H+
concentration!!!
ex. Amino Acids...The building
blocks of proteins!!
Sulfhydryl -SH
 Sulfur atom bonded to an atom of
hydrogen
 Organic compounds with this group are
called thiols
ex. Help stabilize
protein structure
Phosphate
2-OPO3
 Anion formed by dissociation of phosphoric
acid (H3PO4)
 Loss of hydrogen ions by dissociation leaves
phosphate with a negative charge.
 Form organic phosphates
ex. Function in transfer of
energy between organic
molecules, ATP
(adenosine triphosphate)
Methyl -CH3
 Methyl group attached to carbon skeleton
ex. Methyl groups may be added to
DNA to inactivate certain genes
Table 4.1 Functional Groups of Organic Compounds