Enzymes: “Tiny robots”? Thomas Hansen Colegio Colombo Británico March 2017
What is an enzyme? An enzyme is a specialized protein that catalyzes chemical changes in other molecules Catalyze: Speed up the rate of a reaction. Normally, the original reaction is so slow that we would grow old waiting for it without a catalyst. With catalyst Without catalyst
Tiny robots! Enzymes are really good at one thing and one thing only: catalyzing their reaction. One enzyme can make millions of reactions happen every second! In this sense, they are like robots or machines.
What kinds of reactions? DNA replication Breaking down drugs and alcohol Making energy in the mitochondria Storing chemical energy as glycogen Digesting food [Many more] Digesting food
What is this enzyme doing? Digesting a molecule!
O HO O Amylase Amylase is an enzyme (one common place to find it is in your saliva) that digests starch. O HO O What did it do to the molecule? O HO OH Amylase uses water to digest starch! H
Specificity Enzymes can only catalyze their specific reaction. HO O HO O Specificity Enzymes can only catalyze their specific reaction. O HO O What is the difference between this molecule and the previous? O HO This is cellulose, a.k.a. plant fiber. We can’t eat plants because we can’t digest this, even though it’s so similar to starch!
Specificity Enzymes have something called an active site. Only the correct molecule(s) will fit!
Today’s experiment Background: Bromelain is an enzyme (technically a family of enzymes) sold as a powder called “meat tenderizer”. It digests proteins. Pineapples have a lot of bromelain. Gelatin is mostly made of collagen, which is a protein. Question: What will happen to gelatin in the presence of bromelain? Fun fact: Collagen is the protein used in lip injections!
Today’s experiment In one mini-cup, place a piece of fresh (juicy and delicious) pineapple. In a second, place a piece of other fruit. Leave a third empty. Label your cups Add gelatin mixture to fill each cup to be approximately 3/4 full Place your cups on a tray to be put in the fridge
In your notebooks: “Positive control” What are the controls? What is your hypothesis? Why? What would happen if we added saliva to one of the cups? What would happen if we added pineapple to a cup with starch? “Positive control”
Working together Be efficient! Everyone should have something to do. This is a list of tasks that each group must complete: Cut pineapple Cut other fruit to be approximately the same mass as pineapple Measure equal volumes of gelatin solution into the cups Label the cups Answer the questions in your notebooks Place the cups in the freezer Clean up