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Enzyme Notes chapter 5. What are enzymes? Enzymes are cellular proteins that lower the activation energy of chemical reactions in the cell. Enzymes are catalysts.
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Enzyme Notes chapter 5 • What are enzymes? • Enzymes are cellular proteins that lower the activation energy of chemical reactions in the cell. Enzymes are catalysts.
The top curve represents a reaction occurring on its own. “b” represents activation energy, or the amount of energy required to hook molecules together, or to break molecules apart. The curve on the bottom compares how much energy it take with an enzyme… a lot less! How do enzymes work?
How enzymes work, contd • Reactions that contain enzymes will tend to proceed faster because the don’t need as much energy. (a.k.a TIME) • Reactions can only occur with out enzymes if the solution reaches temperatures high enough to cause the molecules to bump into one another. How could temperatures this high affect a living organism?
Enzyme structure • Enzymes are examples of proteins. They form “blobs” because when they are being created in the cells, the amino acid chains need to clump together to conserve space. • The clumping forms grooves called ACTIVE SITES. • Incorrect clumping causes active sites to form improperly.
Why is the shape of the enzyme so important? • If the shape is not formed correctly, the active site groove cannot fit the substrate. • For example: Amylase is an enzyme in saliva which helps to break down polysaccharides. Without amylase, we would not be able to get energy from foods high in starch because we could not break down the individual glucose molecules apart and use them as energy.
Other examples of enzymes • Liver releases bile to break down lipids • Pancreas releases pancreatic juices to help in digestion. • DNA is photocopied using enzymes… no DNA copy, no new cells when you fall and scrape your leg. • Enzymes remove Oxygen from hemoglobin so that it can get into your tissues.. NO enzyme, no oxygen, no working muscles, brain, hearts, etc.
Destroying Enzyme Function • How can you get an enzyme to stop doing its job? • BY DESTROYING ITS SHAPE! ENZYMES STOP WORKING WHEN CONDITIONS ARE NOT RIGHT!
What are the RIGHT conditions? • 1)Specific temperature ranges. (The enzymes in your body work at what temperature? The enzymes in the bacteria that live in the hot springs work at a much higher temperature). • 2) Specific pH ranges (Your stomach enzymes work at what pH? Your mouth?) • 3) Specific substrates to fit into active sites
Denaturation • If any of the 3 conditions are changed, the enzymes can stop functioning either temporarily or permanently. • Sometimes the enzymes break apart and unwinds back to the primary structure: DENATURATIO