Unit Three: Enzymes ph & Buffers Digestion

1. Unit Three:Enzymesph & BuffersDigestion

2. Learning Targets • Identify the characteristics of an enzyme and how they contribute to living things. • Summarize the relationship between an enzyme, substrate, and active site.

3. What is an enzyme? Enzyme: protein that speeds up biochemical reactions by lowering the energy needed for a reaction to happen Catalyst: speeds up a chemical reaction

4. ENZYMES are globular proteins that control chemical reactions in living things. In any living thing, the chance that two molecules (A and B) will meet and react at the right place, the right time, and in the right positions is completely RANDOM.

5. Substrates A A + B + Energy active sites B Enzyme AB + H2O

6. How do enzymes work? • Enzymes attract and hold the substrates. • The substrate fits perfectly into the active site. • Enzymes decrease the amount of activation energy. • The enzyme does its job (usually combines or changes the substrate) and releases it. • The enzyme can be used over and over again. • Everybiological process requires an enzyme. Examples: digestion of food, synthesis of molecules, storage and release of energy)

10. Lock and Key Hypothesis: Proteins bind to each other by matching up knobs and depressions on the proteins surfaces, in much the same way that a key fits into a lock.

12. Lock and Key Hypothesis: Enzyme-Substrate Complex

13. Induced Fit Model Hypothesis: Enzyme slightly changes shapes as the substrate fits in

14. What can affect the rate at which an enzyme does its job? Denature: protein changes its shape due to outside stress on the molecule and stops it from working

15. Factors or Stresses that can affect enzymes can include: Temperature • Enzymes will work faster as temperature increases up until a certain point pH • Extremely high or low pH will denature enzyme

16. Amount of enzyme • More enzymes present, faster product can be made Amount of substrate • More substrate present, faster product can be made up until a certain point

17. Inhibitor: substance that blocks or distorts active site • Reversible • Competitive Inhibitor: closely resembles the shape of substrate and competes for the same active site • Non-competitive Inhibitor: bonds to enzyme in places other than active site • Changes shape of active site, substrate cannot fit • Irreversible • permanently binds to enzyme

21. Vocabulary: • Enzyme • Catalyst • Substrate • Activation Energy • Active Site • Denature • Inhibitor • Completive inhibitor • Non-competitive inhibitor • Lock and Key Hypothesis