Cell signaling in molecular genetics is the essential process by which cells communicate to coordinate various biological functions, including growth, differentiation, metabolism, and gene expression. This communication occurs through signaling molecules such as hormones, neurotransmitters, and growth factors. These molecules bind to specific cell surface or intracellular receptors, triggering a cascade of molecular events that lead to a cellular response.

In the realm of molecular genetics, cell signaling is crucial as it governs how cells interpret and respond to external and internal signals, ultimately influencing gene expression and protein activity. In this unit, we will explore different signaling pathways, focusing on G protein-coupled receptors (GPCRs) and Receptor Tyrosine Kinases (RTKs), along with their associated signaling molecules. Understanding these pathways is vital for grasping how cells maintain homeostasis and adapt to environmental changes.