Final answer:
When a signal molecule interacts with a transport protein, it can cause a transport protein to change shape, opening a gated channel or causing a carrier protein to transit a molecule across the cell membrane. This modifies the cell's permeability to specific ions or molecules, significantly affecting the cell's function and signaling processes.
Step-by-step explanation:
When a signal molecule causes a transport protein to open, the cell membrane experiences a structural change, allowing specific ions or molecules to move across it. This change is typically facilitated by gated ion channels or carrier proteins, which under the influence of various stimuli, can undergo a conformational change leading to the transport of substances.
For instance, nerve cells utilize gated ion channels that open to allow the passage of sodium, potassium, and calcium, which are essential for electrical signal transmission. Carrier proteins, on the other hand, bind to a specific molecule and through an allosteric change in shape, transport the molecule across the membrane. In the context of a cell's response to a signal molecule, these proteins play a crucial role in maintaining cellular function by regulating the internal environment. The type of gated channel may vary, such as ligand-gated or voltage-gated, depending on whether the stimulus is a chemical, electrical, or mechanical force.