Dictionary of Chemistry [6th Ed.]

which thus contains a higher concen-
tration of protons than the matrix.
This creates an electrochemical gra-
dient across the inner membrane,
down which protons move back into
the matrix. This movement occurs
through special channels associated
with ATP synthetase, the enzyme
that catalyses the conversion of ADP
to ATP, and is coupled with the phos-
phorylation of ADP. A similar gradi-
ent is created across the thylakoid
membranes of chloroplasts during
the light-dependent reactions of
*photosynthesis.

chemisorptionSee adsorption.

chemistry The study of the el-
ements and the compounds they
form. Chemistry is mainly concerned
with effects that depend on the outer
electrons in atoms. See biochemistry;
geochemistry; inorganic chem-
istry; organic chemistry; physical
chemistry.

chemoinformaticsThe branch of
chemistry concerned with methods
of representing molecules and reac-
tions and with the design and use of
databases for storing chemical infor-
mation.

ChemSketch A commonly used
chemical drawing program for 2D
and 3D structures, copyright of Ad-
vanced Chemistry Development, Inc.
The program has certain additional

features including calculation of mo-

lecular weight, calculation of per-

centages of elements present, IUPAC

name generation, and viewing in Ras-

Mol.

A

• Details and download from Advanced
  Chemistry Development website

chertSee flint.

Chile saltpetre A commercial min-

eral largely composed of *sodium ni-

trate from the caliche deposits in

Chile. Before the ammonia-oxidation

process for nitrates most imported

Chilean saltpetre was used by the

chemical industry; its principal use

today is as an agricultural source of

nitrogen.

ChimeA plug-in that allows chemi-

cal structures to be displayed within

a web page. The structures, which

are embedded as molÜles, can be

viewed interactively; i.e. they can be

rotated, expanded, exported, and

rendered in *RasMol. The program is

the copyright of MDL Information

Systems, Inc., and is available free

(subject to a license agreement).

A

• A downloadable version of Chime at
  the MDL website (free registration
  required)

china claySee kaolin.

Chinese whiteSee zinc oxide.

119 Chinese white

c

2H+ 2H+ 2H+ inner mitochondrial

membrane

NADH

dehydrogenase

cytochrome

b-c 1 complex

cytochrome

oxidase

mitochondrial matrix

6H+

3ADP + P

3 ATP

ATPaseATPaseATPase

Chemiosmotic theory