Regulatory molecules are biological substances that control various processes within cells. They can include proteins, RNA, and small molecules that influence gene expression, enzyme activity, and cellular signaling pathways. By modulating these processes, regulatory molecules help maintain homeostasis and respond to environmental changes. These molecules play crucial roles in many biological functions, such as cell growth, immune response, and metabolism. For example, transcription factors are regulatory proteins that bind to specific DNA sequences to promote or inhibit the transcription of genes, thereby affecting how cells function and adapt to their surroundings.