Final answer:
Enzymes affect the reactions in living cells by changing the speed of the reaction. They do not change the pH, products, or temperature of the reaction directly, but work optimally within specific temperature and pH ranges.
Step-by-step explanation:
Enzymes affect the reactions in living cells by changing the speed of the reaction. Enzymes are special proteins that catalyze biochemical reactions, which means they increase the reaction rate. Other factors that can influence enzyme activity include temperature, pH, substrate concentration, and the presence of inhibitors or activators. However, it's important to note that while enzymes can greatly speed up reactions, they do not alter the equilibrium or the end products of the reaction. Instead, they simply reduce the activation energy required for the reaction to proceed, allowing it to go forward more quickly.
At a basic level, increasing the temperature generally speeds up reactions, but for enzymes, there exists an optimal temperature range beyond which they become denatured and lose their functionality. Similarly, each enzyme has an optimal pH at which it functions best, and deviations from this range can lead to loss of activity due to denaturation. Enzyme concentration itself is also a factor; greater amounts of the enzyme can increase the rate of reaction up to a point, assuming substrate is not limited.