Final answer:
The same signal molecule can induce different responses in different target cells due to variation in protein expression, signal integration, and the interplay between different signaling pathways.
Step-by-step explanation:
The same signal molecule can induce different responses in different target cells due to several factors:
- Variation in protein expression: Different cell types produce different receptors that bind to the same ligand or the same receptor that binds to the same ligand with different signaling components, activating different responses in each cell.
- Signal integration: Signals from two or more different cell-surface receptors can merge to activate the same response in a cell, ensuring multiple external requirements are met before a cell commits to a specific response.
- Cellular proteins: Most cellular proteins can affect different downstream events, causing a single signaling pathway to branch off toward different endpoints based on the interplay between two or more signaling pathways.