Enzymes are vital biological catalysts that drive nearly all biochemical reactions essential for human cellular function. Their activity is highly sensitive to environmental factors, particularly temperature and pH, which directly influence enzyme structure, catalytic efficiency, and cellular homeostasis. Disruptions in these conditions can lead to enzyme denaturation, metabolic imbalance, and the development of disease.This preprint presents a focused, literature-based analysis of the effects of environmental conditions on enzyme activity and their implications for human cellular health. It examines the structural basis of enzyme function, the genetic regulation of enzyme production, and the molecular mechanisms underlying temperature- and pH-dependent changes in enzymatic performance. The study further explores the physiological and pathological consequences of enzyme dysfunction, including metabolic disorders and cellular stress.By integrating principles from biochemistry, molecular biology, and human physiology, this work highlights the critical importance of maintaining optimal cellular environments to preserve enzyme function and overall human health. This research is presented as an independent student preprint intended to support scientific discussion and educational research in enzymology.