Welcome Back! Do Now Turn in Lab 04 Answer: What is pH? What is an acid? What is a base? What is the range of the pH scale? If I have a solution that has a pH of 7, is it an acid, base, or neutral? What is the neutral solution that we learned?

A little background information. Before we begin… A little background information.

Chemical Reactions A chemical reaction is a process that changes one set of chemicals into another set of chemicals Reactants: elements or compounds that enter into a chemical reaction Products: elements or compounds produced by a reaction Activation Energy: the energy that is needed to start a reaction

Activation Energy Some reactions occur quickly… Other chemical reactions occur slowly…. H gas ignited in the presence of O = rapid and explosive reaction Such as the combination of iron and oxygen to form an iron oxide called rust

What helps speed up these reactions…? Activation Energy Some chemical reactions that make life possible are too slow or have activation energies that are too high to make them practical for living tissue What helps speed up these reactions…?

Can you name a catalyst that we learned…? Catalysts! Cells make catalysts to make certain chemical reactions possible! Catalyst: a substance that speeds up the rate of chemical reaction Works by lowering a reaction’s activation energy. Can you name a catalyst that we learned…?

Enzymes

What Are Enzymes? All enzymes are made from proteins Enzymes are catalysts - accelerate a reaction Structure is not changed in the process

Enzymes Are specific for their substrate Are Reusable End in –ase Substrate: reactants of an enzyme-catalyzed reaction Are Reusable End in –ase -Sucrase, lactase, maltase Catalyze = to break down; digestion Synthesize = start with 2 to make 1 Similar to reactant and product, you have substrate and product

How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy Animation

A Lock and Key! It’s Something like… shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

Activity Enzyme Cut out

Welcome Back! Do Now Turn in homework! Answer: What is activation energy? What are catalysts? What are enzymes? What is the enzyme-substrate complex? What does the “lock and key” analogy mean? Lock & Key shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

Re-Loop: Enzyme-Substrate Complex

Enzyme-Substrate Complex Joins Substrate: the substance (reactant) an enzyme acts on

Enzyme-Substrate Complex Active Site Enzyme Substrate Active Site: a restricted region of an enzyme molecule which binds to the substrate.

What Affects Enzyme Activity? Three factors: Environmental Conditions pH Enzyme Inhibitors

1. Environmental Conditions Extreme Temperature are the most dangerous - high temps may denature (unfold) the enzyme. pH (most like 6 - 8 pH near neutral) Ionic concentration (salt ions)

1. Environmental Conditions Effect on rates of enzyme activity Optimum temperature greatest number of collisions between enzyme & substrate human enzymes = 35- 40C (body temp = 37C) Raise temperature denature protein = unfold = lose shape Lower temperature molecules move slower decrease collisions

Effect on rates of enzyme activity 2. pH Effect on rates of enzyme activity pH changes protein shape most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

Competitive inhibitors 3. Enzyme Inhibitors 3 Inhibitors: Competitive inhibitors Substrate and a substance resembling the substrate are both added to the enzyme. Enzyme Substrate Competitive inhibitor

2. Noncompetitive inhibitors: 3.Enzyme Inhibitors 2. Noncompetitive inhibitors: Molecule binds to an enzyme somewhere other than the active site.  molecule binds to an enzyme somewhere other than the active site. This changes the enzyme's three-dimensional structure so that its active site can still bind substrate with the usual affinity, but is no longer in the optimal arrangement to stabilize the transition state and catalyze the reation. Enzyme Noncompetitive Inhibitor Substrate active site altered

Excessive amounts of substrate are present 3.Enzyme Inhibitors 3. Substrate Inhibition Excessive amounts of substrate are present Enzyme Substrate Substrate Substrate Substrate

Murder And A Meal: The Case Lab 05

Welcome Back! Do Now Turn in lab 5! Answer: What is the enzyme-substrate complex? What does the “lock and key” analogy mean? What happens if enzymes encounter extreme temperatures? What is the pH of most enzymes? Name the three enzyme inhibitors Lock & Key shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

Agenda Do Now Group Test Review Review Scavenger Hunt Test = FRIDAY

Welcome Back! Do Now Get ready for your test! Answer: How do you feel about this class so far? What improvements can Ms. Fields make to make this class better for you. Lock & Key shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

It’s almost test time… Quick Review

Review topics Organic, inorganic Carbohydrates – monomers and polymers Monosaccharides Glucose, galactose, fructose Starch = energy in plants Cellulose = structure in plants Proteins When ingested by animals = amino acids Chemical indicators Brown bags, Benedict’s, Iodine, Biuret

Review topics Hydrolysis Dehydration Synthesis Addition of water to break polymers into monomers Dehydration Synthesis Removing water to make monomers into polymers Enzymes – put together (synthesize) or break apart (decompose) substances; speed up reactions Catalase Are chemically specific (they only work with the particular substrate) Denaturing STERNGRR