Final answer:
The correct sequence in cell signaling starts with a ligand binding to a receptor, activating a signaling pathway involving second messengers and kinases, leading to a chain reaction that alters the cell's environment and results in an appropriate cellular response.
Step-by-step explanation:
The correct sequence of events involved in cell signaling begins with the binding of a ligand to a cell-surface receptor. Following this event, the activation of the receptor's intracellular components initiates a signaling pathway or cascade. During this pathway, second messengers and enzymes such as kinases modulate the function of various proteins through processes like phosphorylation. These proteins in turn activate other proteins in a chain reaction, leading to changes in the cell's environment - this can involve alterations in metabolism, gene expression, and ultimately cellular response.
Examples of second messengers include calcium ions (Ca²+), cyclic AMP (cAMP), diacylglycerol (DAG), and inositol triphosphate (IP3). Ultimately, the cell's response might be to alter protein synthesis, change metabolism rates, prompt cell growth, or initiate programmed cell death (apoptosis). The termination of the signaling cascade is equally important to ensure the appropriateness of the response in timing and intensity, which can involve the degradation of signaling molecules or dephosphorylation of intermediates by phosphatases.