(2) Saturation kinetics indicates that a lipid-soluble carrier molecule is involved in the passage of the solute across the membrane. When all the carrier molecules are occupied with the solute, the rate of influx becomes constant.
(3)
Facilitated
diffusion
is
stereospecific,
i.
e.
only
one
of
the
two
possible
isomers,
L-or
D
is
transported
(4) It has been frequently stated that no metabolic energy is required for facilitated diffusion. Work with E. coli has, however, shown that facilitated diffusion does not take place unless there is a source of energy. This claim has been supported by later investigations
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