- The movement
of ions in or out of a cell through
a cell membrane from a region of their
lower concentration to a region of their higher concentration, against
a concentration gradient using energy
released during respiration in the mitochondria.
- In this process transporter
proteins in the cell membrane attach
to a substrate, and then change shape to transfer it into the
- e.g. In the large intestine, by uptake of minerals by
plants or by kidneys to reabsorb glucose from urine.