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Notes – Chapter #4AA Carbon And The Molecular Diversity Of Life
Intro:
1. Aside from water, most biologically important molecules are carbon based.
2. Carbon enters the biosphere through the action of plants.
3. Plants use solar energy to transform atmospheric carbon dioxide into the
Molecules of life, which are then taken in by plant-eating animals.
I. Organic Chemistry Is The Study Of Carbon Compounds
1. Compounds containing carbon are said to be organic, and the branch of
chemistry that specializes in the study of carbon compounds is called
organic chemistry.
2. Differences in individuals within a species, are distinguished by variations
in their organic molecules.
3. The science of organic chemistry originated in attempts to purify & improve
the yield of various valued substances.
4. However, at that time , it was believed that organic compounds could only
arise in living organisms.
5. Jon Berzelius made the distinction between organic compounds, ( those
thought to arise only in living organisms, and inorganic compounds (those
found only in the nonliving world.
6. Vitalism, the belief in a life force outside the jurisdiction of physical and
chemical laws, provided the foundation for the discipline of organic
chemistry.
7. Various chemists were able to synthesize organic compounds in the laboratory by combining elements under the right conditions.
a) Wohler – in attempt to make the salt ammonium cyanate, he synthesized
urea.
b) Kolbe – synthesized the organic compound acetic acid.
8. Finally, in 1953, Stanley Miller set up a closed system to mimic conditions
thought to have existed on the early Earth. From the results, Miller concluded that complex organic molecules could arise spontaneously under
conditions thought to have existed on the early Earth. Miller refuted the
principle of vitalism.
9. These pioneers of organic chemistry helped shift the thought from vitalism
to mechanism.
10. Mechanism is the view that physical and chemical laws govern all natural
Phenomena, including the process of life.
II. Carbon Atoms Can Form Diverse Molecules By Bonding To Four Other
Atoms
A. The Formation Of Bonds With Carbon
1. Carbon with a valence of 4 can bond to various other atoms, including O,
H, and N.
2. Carbon can also bond to other carbon atoms, forming the carbon skeletons of
organic compounds.
B. Molecular Diversity Arising From Carbon Skeleton Variation
1. The skeletons vary in
a) length
b) it may be straight, branched, or arranged in closed rings
c) some carbon skeletons have double bonds, which vary in number & location.
d) atoms of other elements can be bonded to the skeletons at available sites.
C. Hydrocarbons
1. Hydrocarbons are organic molecules consisting of only carbon and hydrogen.
2. The hydrophobic compound, fat does not dissolve in water because the great
majority of their bonds are relatively nonpolar carbon-to-hydrogen linkages.
D. Isomers
1. Isomers are compounds that have the same number of atoms of the elements
but different structures and hence different properties.
2. Three types of isomers are
a) Structural isomers – structural isomers differ in covalent arrangements of
their atoms.
b) Cis-trans isomers – (formerly called geometric isomers), carbons have
covalent bonds to the same atoms, but these atoms differ in their spatial
arrangement due to the inflexibility of double bonds.
c) Enantiomers – are isomers that are mirror images of each other and that
differ in shape due to the presence of an asymmetric carbon (one that is
attached to four different atoms).
III. A Few Chemical Groups Are Key To The Functioning Of Biological
Molecules
1. Chemical groups attached to the carbon skeletons of organic molecules
participate in chemical reactions. These functional groups contribute
to function by affecting molecular shape.
2. The seven chemical groups most important in biological processes are
a)
b)
c)
d)
e)
f)
g)
hydroxyl
carbonyl
carboxyl
amino
sulfhydryl
phosphate
methyl
3. See pages 64 & 65 for the structure, name of compound, example &
functional properties. Know the bold faced information.
A. ATP: An Important Source of Energy for Cellular Processes
1. ATP is a nucleotide consisting of adenosine, attached to three phosphate
groups. (A nucleotide consist of - a sugar, a base & a phosphate)
2. ATP can react with water forming inorganic phosphate and ADP
(adenosine diphosphate) . This reaction releases energy that can be used
by the cell.