Microsoft word - enzymes worksheet[1].doc

We've been talking about the kind of reactions that happen in your body (DNA, Protein synthesis, Cellular respiration etc.) and how molecules can change. You should know that It doesn't happen on its own. If you leave a blob of protein in a petri dish will it just break down to the amino acids? No. What will break down proteins? Enzymes! Enzymes are the biological substance (proteins) that act as CATALYSTS and help complex reactions occur everywhere in life. A catalyst is a substance that increases the rate of a chemical reaction by reducing the amount of energy needed to start that reaction. Considering that there are an estimated 75,000 different enzymes in the human body, these chemical reactions are performed at an amazing rate. On the other hand, in the absence of enzymes, reactants may take hundreds of years to convert into a usable product, if they are able to do so at all. This is why enzymes are crucial in the sustenance of life on earth. The absence of enzymes is responsible for many diseases. In humans, a tragic disease called phenylketonuria (PKU), which causes severe mental retardation and even death in infants, is the result of the absence of one type of enzyme. Tay-Sachs disease is a similarly tragic result of an enzyme deficiency. It causes retardation, paralysis, and often death in early childhood when left untreated. Our ability to alter enzymes by inhibiting their functioning abilities has resulted in hundreds of life saving drugs. One example is penicillin, a well-known antibiotic that can cure syphilis, pneumonia, and other illnesses. Penicillin works by bonding to the active sites of the disease-causing bacteria’s enzymes, ultimately destroying the bacteria’s ability to survive and reproduce. LOCKS AND KEYS When you go home at night and the door is locked, can it open itself? Nope. You need a key that is just the right shape to fit in that lock. Otherwise you're stuck in the cold. Enzymes work in a similar way. Enzymes complete very specific jobs and do nothing else. They are very specific locks and the compounds they work with are the special keys. Here's the deal. There are four steps in the process of an enzyme working. (1) An enzyme and a SUBSTRATE are in the same area. The substrate is the biological molecule that the enzyme will work on. (2) The enzyme grabs onto the substrate with a special area called the ACTIVE SITE. The active site is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock. (3) A process called CATALYSIS happens. Catalysis is when the substrate is changed. It could be broken down or combined with another molecule to make something new. (4) The enzyme lets go. Big idea - When the enzyme lets go, it returns to normal, ready to do another reaction. The substrate is no longer the same. The substrate is now called the PRODUCT. CAN YOU STOP THEM? Good question! We know what you're thinking. What if enzymes just kept going and converted every molecule in the world? It would never stop. like a monster! Not like a monster, but you're on the right track. Enzymes sometimes need to be controlled. Other times they are controlled because of poisons and contaminants. So what affects enzyme activity? (1) TEMPERATURE: That's a good one. Proteins change shape as temperatures change. Because so much of an enzyme's activity is based on its shape, temperature changes can mess up the process and the enzyme won't work. (2) ACTIVATORS: Sometimes you need an enzyme to work faster and your body creates an activator. Other times you might eat something that acts as an activator. Activators make enzymes work harder and faster. If you're running in a race and you need more energy. Get those enzymes to work! (3) pH LEVELS: In the same way that temperature can change the shape of proteins, the acidity of the environment does the same thing. Remember that the pH is a measure of how acidic or basic something is. (4) INHIBITORS: These are the opposite of activators. Inhibitors either slow down or stop the activity of an enzyme. They often bond to the protein and the shape changes. Remember - When the shape changes, the enzyme will not work the same way. A nasty example of an inhibitor is snake venom or maybe nerve gas from World War I. NAME: __________________________________ DATE: ___________ PERIOD: _______ After Reading the information on enzymes answer the following questions: 1. _____________________________________________________________________ _____________________________________________________________________ 2. What is a catalyst? ____________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 3. What is a substrate? __________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 4. What is the active site and what is its job?_________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 5. What is catalysis? ____________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 6. What is the product? __________________________________________________ _____________________________________________________________________ 7. How do enzymes work?_________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 8. What 4 things can affect the way enzymes work? Explain how each thing affects an 1) ______________________________________________________________ 2) ______________________________________________________________ 3) ______________________________________________________________ 4) ______________________________________________________________

Source: http://mrbiology.info/labs/enzyme/labarticle.pdf