Modelling Topics Subtopics : Movement Of Substances Across The Plasma

Modelling Topics

: Movement of substances across the plasma membrane

Subtopics

: Active transport

Learning Outcomes : a) To explain the movement of substances across the plasma membrane through the

process of active transport. 1. Active transport is the mediated process of moving particles across a biological membrane against a concentration gradient. It requires: •

a transmembrane protein (usually a complex of them) called a transporter

•

energy. The source of this energy is ATP.

2. The energy of ATP may be used directly or indirectly. •

Direct Active Transport. Some transporters bind ATP directly and use the energy of its hydrolysis to drive active transport.

•

Indirect Active Transport. Other transporters use the energy already stored in the gradient of a directly-pumped ion. Direct active transport of the ion establishes a concentration gradient. When this is relieved by facilitated diffusion, the energy released can be harnessed to the pumping of some other ion or molecule.Some particles cannot across the phospholipid bilayer due to the semi-permeable membrane just allow some particles to accross it.

The variable can be manipulate to see the result

3. The Phosphate group from ATP used to activate the calsium transport channel.

The concentration of ATP and CA+2 can be manipulate

The movement of particles across the plasma membrane can be seen by cliking on ‘load model’ button

4. The calsium ions can easily move out with presents of ATP.

The calcium concentration inside and outside the cell can be obtain from this bar.

The chemical energy and the voltage (electric potential) occur in active transport can be obtain from this bar