Chemistry Reference
In-Depth Information
WHY DO WE NEED ANYTHING OTHER THAN C, H, N, AND O
(TOGETHER WITH SOME P AND S)?
The word 'organic' itself can have a large number of meanings. The chemical definition is 'applied to a class of
compound substances which naturally exist as constituents of organised bodies (animals or plants), or are formed
from compounds which so exist, such as organic acids, bases, molecules, radicals: they all contain or are derived
from hydrocarbons'. Hence, organic chemistry is the chemistry of hydrocarbons and their derivatives, or more
generally, 'any chemical compound containing carbon'. However, in this latter definition, some simple
compounds of carbon, like carbon dioxide, are sometimes classified as inorganic compounds. Of course, we
quickly perceive that carbon alone does not suffice for life
e
we would not be able to do much with just the three
elemental forms of carbon, graphite, diamond, and fullerenes
1
(the latter is illustrated below in
Fig. 1.1
by the
FIGURE 1.1
Buckminsterfullerene a 60 carbon 'bucky ball', made entirely and exclusively of carbon.
structure of Buckminsterfullerene, a spherical molecule with the formula C
60
, so named in honor of the geodesic
domes of Richard Buckminster Fuller, which they resemble). We also need hydrogen, oxygen, nitrogen, a non-
negligible dose of phosphorus, as well as some sulfur.
It follows that, with the inclusion of oxygen, nitrogen, phosphorus, and sulfur, we escape from the relatively
restricted sphere of hydrocarbons made up solely of carbon and hydrogen, and enter a brave new world of organic
molecules
acids, aldehydes, ketones, alcohols, amines, sugars, amino acids, and lipids. From these organic
building blocks, we can construct proteins, polysaccharides, fats, nucleic acids, even phospholipid bilayers (which
together with proteins, constitute the structural leitmotif of biomembranes).
Yet, a living cell does not just require these organic building blocks, together with the biopolymers, and the
biomembranes. The enormous negative charges that are generated along the polyphosphate backbone of nucleic
acids need to be balanced with appropriate positively charged counter-ions. In order to generate ATP, our universal
energy currency, we need to separate proton transport from electron transfer, and use the energy of proton
e
1. Fullerenes are molecules composed entirely of carbon, in the form of ellipsoids, spheres or tubes. Spherical fullerenes are called 'bucky
balls'.
