Final answer:
Cell-to-cell communication relies on the specific matching shapes of ligands (chemical messages) and their receptors on cell surfaces, emulating a 'lock and key' mechanism. This interaction is critical for the precise signaling pathways and subsequent cellular responses in direct contact or distant signaling events.
Step-by-step explanation:
The relationship between the shape of a chemical message and its receptor molecule is crucial for cell-to-cell communication, whether it occurs through direct contact or from a distance. This type of communication is often based on the 'lock and key' model, where the chemical message, or ligand, acts as a 'key' that specifically fits into the 'lock,' which is the receptor on the target cell's surface. If the shape of the ligand matches the shape of the receptor, a signal can be transferred into the cell, initiating a cellular response.
For example, neurotransmitters released from a neuron bind to receptors on another cell, leading to a response in that cell, which could be a neuron, muscle cell, or gland cell. If the shapes do not match, the chemical message will not bind to the receptor, and no signal will be sent. This specificity ensures that cells can communicate accurately and efficiently, triggering appropriate responses.