Active Processes Across
Membranes
Active Transport
Movement of substances against their concentration gradient
Low to high concentration
Requires ATP because more energy is needed than passive processes, which use the
integral kinetic energy of molecules
Energy is provided y the hydrolysis of ATP
This energy is needed to allow the carrier protein to change its shape to carry ions to
the other side of the membrane
Carrier Proteins
Have specific sites which combine reversibly with certain solute molecules or ions
Also have specific regions which bind to, and allow the hydrolysis of, ATP to release
energy – through this they act as an enzyme by catalysing the hydrolysis reaction
Energy allows them to change their conformation (shape) and in doing so they carry the
ion from one side to the other
Membranes
Active Transport
Movement of substances against their concentration gradient
Low to high concentration
Requires ATP because more energy is needed than passive processes, which use the
integral kinetic energy of molecules
Energy is provided y the hydrolysis of ATP
This energy is needed to allow the carrier protein to change its shape to carry ions to
the other side of the membrane
Carrier Proteins
Have specific sites which combine reversibly with certain solute molecules or ions
Also have specific regions which bind to, and allow the hydrolysis of, ATP to release
energy – through this they act as an enzyme by catalysing the hydrolysis reaction
Energy allows them to change their conformation (shape) and in doing so they carry the
ion from one side to the other
