Enzymes

Enzyme Demonstration Starch is digested by the enzyme amylase found in saliva. Amylase in saliva, starch in paper…so if I draw on paper with saliva, amylase can break down the starch. What will happen when I stain with iodine? Ask 4 0r 5 volunteers Take a sterile swab, insert it in your mouth to saturate it with saliva, use it to write a secret message on a piece of paper. Wait 5 minutes then spray with dilute starch.

Vocabulary 1. Enzyme: biological catalyst Slide # 3 Vocabulary 1. Enzyme: biological catalyst 2. Substrate: substance that an enzyme works on 3. Active site: place on enzyme where substrate attaches to enzyme 4. Enzyme-substrate complex: molecule that forms when substrate is bound to enzyme 5. Product: substance formed as a result of enzyme action

Activation Energy Activation Energy needed without Enzyme Slide # 4 Activation Energy Activation Energy needed without Enzyme Activation Energy needed with Enzyme Available energy given off

Enzymes are 1. Proteins that catalyze chemical reactions. Slide # 5 Enzymes are 1. Proteins that catalyze chemical reactions. Catalyst –speeds up rate of chemical reactions 2. Catalysts for biological reactions. Lower the energy required to make a reaction occur. Lowers the activation energy They don’t make any reactions happen that wouldn’t have happened anyway

Types of Enzymes 1. Food enzymes: break down polymers into monomers Slide # 6 Types of Enzymes 1. Food enzymes: break down polymers into monomers 2. Metabolic enzymes: control chemical processes that occur in the body

Digestive Enzymes 1. Salivary amylase: digests carbohydrates Slide # 7 1. Salivary amylase: digests carbohydrates 2. Pepsin: digests proteins 3. Lipase: digests lipids Digestive enzymes break polymers down into monomers

Enzymes lower the amount of energy needed to start a reaction. Slide # 8 Metabolic Pathways Enzymes lower the amount of energy needed to start a reaction. Enzyme A Enzyme B Substrate 1 Bi-Product End Product If Enzyme B is NOT present, can the product be made? What is the purpose of Enzyme A ?

About Enzymes 1. Enzymes are proteins. Slide # 10 About Enzymes 1. Enzymes are proteins. 2. Enzymes are specific; can only catalyze ONE chemical reaction. 3. Only a small amount of enzyme is produced 4. Enzymes DO NOT get used up; they are reused over and over again. 5. Enzymes can become saturated (more substrate that enzyme). To increase the amount of product, you have to add more enzyme

Enzymes are not Changed in Reactions At the end of the reaction, the enzyme (sucrase) is free to catalyze another reaction.

Enzymes are Affected By: Slide # 11 Enzymes are Affected By: 1. Temperature: heat destroys enzymes 2. pH: destroys enzymes 3. Amount of substrate: can saturate enzymes 4. Inhibitors: keep the enzymes from doing its job

Type of Inhibitors 1. Competitive inhibitors: compete for active site Slide # 12 Type of Inhibitors 1. Competitive inhibitors: compete for active site Slows rate of product formation 2. Noncompetitive inhibitors: attaches to another site; changes shape of active site Noncompetitive inhibitor changes shape of active site Competitive inhibitor blocks active site

Review: What are enzymes? What do they do? What is a substrate? What is an active site? What is induced fit? What is an enzyme substrate complex? How does catalase fit the model?