Enzymes and the catalase lab Chapter 2 – Biochemistry You’ve had most of this material; today’s info is mostly review (paraphrase what’s new or important to you)

Enzymes and chemical reactions Chemical reaction: One or more chemicals (reactants) react to form different chemicals (products) Reactant(s)  Product(s) Enzymes speed up chemical reactions in cells/organisms Often millions of time faster! Speed up = “catalyze” ENZYMES ARE ONE TYPE OF PROTEIN

How enzymes work Enzymes provide a site for chemicals to come together to react – like a “lock and key” Enzymes are specific – only help certain chemicals react. (Animation – describe in notes)Animation Enzymes may break down molecules (e.g. food) or synthesize molecules (e.g. building new proteins)

What affects enzyme reaction rates? What affects enzyme speed? How much are produced by cells (more = faster) Mixing (more = faster) Temperature (warmer often = faster*) pH (the effect varies) If conditions become unfavorable (too hot, too acidic, etc), enzyme becomes “denatured” Denatured protein – tertiary structure becomes permanently altered, making protein not work The “lock” and “key” no longer fit together

Enzyme examples Rennin Produced by cow stomach lining Used to curdle milk to make cheese Papain Present in papayas Breaks down proteins in meat (meat tenderizer), some venoms Amylase In saliva Breaks down starch – into glucose

More examples… Cellulase In bacteria and fungi, mostly Can be used to make ethanol from corn, sugar Catalase (the focus of our upcoming lab)

Catalase Lab! Catalase is an enzyme (“-ase” = enzyme) Present in your liver cells (and cells of many other organisms) Breaks down hydrogen peroxide (a toxic cell waste product) into water and oxygen 2H 2 O 2  2H 2 O + O 2 One catalase molecule Breaks down 40 million H 2 O 2 molecules per second! Demo – catalase in action

Catalase lab Each lab group: Design, conduct an experiment How does (choose a variable) affect the rate of the catalase and hydrogen peroxide reaction? Note: the type of catalase we’ll use typically functions best at about 20 degrees C Choose from these possible variables to test: Heat (Increasing temp) Cold (Decreasing temp) pH (increased or decrease pH) Catalase concentration (more dilute)

Catalase lab Each lab group: Time to discuss MV, hypothesis, introduction Each student: Introduction due Monday Typed is best, handwritten is ok Just question, hypothesis, background info Nothing about the procedure, yet Entire lab report due later… Review rubric now… I’ll explain procedure tomorrow.