Science ObjectDigital resources are stored online in your NSTA Library.
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates how the reaction rates in cells can be affected by temperature, pH, hydration levels, and enzymes.
Chemical reaction rates are affected by the conditions in which they occur (or cannot occur). Most cells must function within a narrow range of temperature and acidity because they are part of a living system. At very low temperatures, reaction rates are too slow. High temperatures and/or extremes of acidity can irreversibly change the structure of most protein molecules. Even small changes in acidity can alter the molecules and how they interact. Hydration levels also affect chemical reactions in cells; dehydrated cells lack the solvent and substrate or substrate structure needed for chemical reactions to proceed.
Both decomposition and synthesis of molecules (involving energy transfer) are made possible in cells by a large set of protein catalysts, called enzymes. Without enzymes to catalyze the chemical reactions necessary for life, the conditions (including temperature) inside of cells would slow chemical reaction rates below what is necessary to stay alive. Like other protein reactions, the effectiveness of enzymes reactions is affected by temperature and acidity.