 An enzyme is a biological catalyst. A catalyst speeds up the rate of a reaction without being consumed in the reaction itself. Think back to the time when you learned how to ride a bicycle. You may have had someone help you keep the bicycle upright as you learned. That person who helped you is like a catalyst. The process of learning how to ride a bicycle is made to be more efficient and you may have learned faster. However, this process only requires two key factors, you and the bicycle. An enzyme is rather unique in a sense that its function is specific to a certain substrate. These enzymes contain an active site. This is where the substrate latches on to and where catalytic activity occurs. Think of it as a keyhole for a key. Only one key can fit in any given keyhole. We can tell if something is an enzyme just from its name. Most enzymes have the suffix A's. The prefix tells us what that enzyme is specific to. Proteases are enzymes that break proteins apart into their original amino acids. Lipases are enzymes that break apart lipids or fats into fatty acids and glycerol. What do you think is the name of the enzyme that breaks apart cellulose into sugars? Pause, think, and continue when ready. The answer is cellulase. Some washing powders contain proteases and lipases. These are known as biological detergents as proteases and lipases come from living organisms. When you spill food or drink on your favorite shirt, the stains are actually little bits of protein and fat. So the proteases and lipases break down these stains to be washed away. Similarly, when you fall down and hurt yourself, the blood stains on your clothing can be difficult to remove. But this is made easier with these biological detergents as the proteases can break down hemoglobin in blood to be cleaned off. Another possible alternative is to use bleach or sodium hypochlorite. The issue here, however, is that it could damage clothing and remove pigment dyes along with the stain, leaving a big white spot. Why aren't cellulases usually added to these biological detergents? Here's a hint. The main component of cotton fibers is cellulose. Pause, think, and continue when you have an answer. If we added cellulase to washing powders, this could damage some clothing because its function is to break down cellulose. It would slowly eat away at your favorite cotton shirt, making it thin and dull. However, we can add amylases, which break down amylose in starchy foods. There are many advantages to using these biological detergents. These enzymes have an optimal temperature of around 40 degrees Celsius. High temperatures will denature the enzyme, causing it to lose its shape and therefore its effectiveness. This means that your laundry can be done in warm instead of hot water, thereby costing less energy to heat water. Therefore, these detergents are very energy efficient and environmentally friendly. Being warm instead of hot water can preserve your clothing. Not much shrinkage occurs, and the colors stay bright for a longer period of time. As well, when these proteases and lipases are washed away into larger bodies of water, they present no immediate threat to the environment or any living organisms. This is because they are biodegradable, which means that microbes in the environment can break them apart rather easily.