Chapter 4 Carbon and the Molecular Diversity of
Life Lecture Outline
Overview: 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 elements.
These other elements commonly include hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and
Concept 4.1 Organic chemistry is the study of carbon compounds
The study of carbon compounds,
deals with any compound with carbon
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 distinguish even between individuals of a single species.