Carbon and the Molecular Diversity of Life
A. Carbon—The Backbone of Biological Molecules
Although cells are 70–95% water, the rest consists mostly of carbon-based compounds.
Carbon is unparalleled in its ability to form large, complex, and diverse molecules.
Carbon accounts for the diversity of biological molecules and has made possible the
great diversity of living things.
Proteins, DNA, carbohydrates, and other molecules that distinguish living matter from
inorganic material are all composed of carbon atoms bonded to each other and to atoms of other
These other elements commonly include hydrogen (H), oxygen (O), nitrogen (N), sulfur
(S), and phosphorus (P).
1. Organic chemistry is the study of carbon compounds.
The study of carbon compounds,
deals with any compound with
carbon (organic compounds).
Organic compounds can range from simple molecules, such as CO
, to complex
molecules such as proteins, which may weigh more than 100,000 daltons.
The overall percentages of the major elements of life (C, H, O, N, S, and P) are quite
uniform from one organism to another.
However, because of carbon’s versatility, these few elements can be combined to build
an inexhaustible variety of organic molecules.
Variations in organic molecules can even account for differences among individuals of
the same species.
The science of organic chemistry began in attempts to purify and improve the yield of
products obtained from other organisms.
Initially, chemists learned to synthesize simple compounds in the laboratory, but had no
success with more complex compounds.
The Swedish chemist Jons Jacob Berzelius was the first to make a distinction between
organic compounds that seemed to arise only in living organisms and inorganic compounds that
were found in the nonliving world.
This led early organic chemists to propose
the belief that physical and chemical
laws did not apply to living things.
Support for vitalism began to wane as organic chemists learned to synthesize complex
organic compounds in the laboratory.