Warm-Up: What are the 4 macromolecules and what are their monomers? Macromolecule QUIZ!

And Chemical Reactions! Enzymes! And Chemical Reactions!

CA Biology Standard Students know enzymes are proteins that catalyze biochemical reactions without altering the reaction equilibrium and the activities of enzymes depend on the temperature, ionic conditions, and the pH of the surroundings.

What are Chemical Reactions? Chemical reactions are processes that change one set of chemicals (reactants) into another set of chemicals (products) by breaking the bonds of the reactants and forming new bonds in the products. This releases or absorbs energy. Reactant + Reactant  Product + Product You would not be alive without chemical reactions occurring in your body all the time!

Balancing Chemical Equations Carbon Dioxide must be converted into Carbonic Acid to dissolve in your blood. Carbon Dioxide + Water yields Carbonic Acid CO2 + H2O  H2CO3 Is it balanced? Count the atoms. C = H= O=

Balancing Chemical Equations Chemical Equation for Rust: Fe + O2  FeO3 Is it balanced? Count the atoms. Fe= O= 2Fe + 3O2 2FeO3

Balancing Chemical Equations Chemical Equation for Photosynthesis: Carbon Dioxide + Water yields Glucose + Oxygen CO2 + H2O  C6H12O6 + O2 Is it balanced? Count the atoms. C= H= O= Balanced Equation: 6CO2 + 6H2O  C6H12O6 + 6O2

Enzymes are proteins that act as biological catalysts. Catalysts are substances that speed up the rate of a chemical reaction. They work by lowering the activation energy. Most cellular reactions occur about a million times faster than they would in the absence of an enzyme.

Energy in Reactions Chemical Reactions either release energy and can occur spontaneously or absorb energy and require an input of energy to occur. Activation Energy is the energy needed to get a reaction started. Period 2 stopped here.

Enzyme names usually end in –ase. Sucrase catalyzes the hydrolysis of sucrose into glucose and fructose. Lactase catalyzes the hydrolysis of lactose into galactose and glucose. Lactase is essential to digest lactose in milk. Deficiency of the enzyme causes lactose intolerance. Amylase is an enzyme that breaks starch down into sugar. It is present in human saliva, where it begins the chemical process of digestion. Foods that contain much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns some of their starch into sugar in the mouth.

Enzyme Names and Types Lipase catalyzes the hydrolysis of a lipid. DNA Polymerase reads an intact DNA strand as a template and uses it to synthesize the new strand of DNA. Pepsin, Trypsin, and Chymotrypsin catalyze the hydrolysis of proteins. Rennet is a complex of enzymes produced in any mammalian stomach to digest the mother's milk and is used in the production of cheese

How do enzymes work? Enzymes provide a site, the active site, where reactants (called substrates) are brought together to react. Substrates bind to this active site which has a very specific shape that only the substrate can fit. (Think of a lock and key.) Together, the substrate and enzyme are called the enzyme-substrate complex. The chemical reaction occurs, products are created and then released from the enzyme.

Properties of Enzymes

1. Enzymes are reusable. Once the chemical reaction is complete, then the substrates are released and the enzyme can start the process again, with new substrates. Period 4 stopped here 3/17/11

pH and Enzyme Function 2. Each enzyme functions best within a certain pH range. The enzyme pepsin, (in your stomach) functions best in a strongly acidic environment. Lipase, (in your small intestine) works best in a basic environment. When the pH is too high or too low, the active site gets denatured and the enzyme cannot catalyze reactions.

Temperature and Enzyme Function 3. A. Chemical reactions speed up as temperature is increased, so catalysis will increase at higher temperatures. 3. B. However, each enzyme has a temperature optimum, and beyond this point the enzyme's functional shape is lost (denatured). Period 0 stopped here 9/28/10

Temperature and Enzyme Function 3. C. Boiling temperatures will denature most enzymes, which means that they will lose their structure and therefore, their function.

4. Substrate Concentration As the concentration of the substrate increases, the speed of the chemical reaction increases, up to a certain point.

Checkpoint- What did you learn? What happens to chemical bonds during a chemical reaction? How do you balance a chemical reaction? What are enzymes and why are they important to living things? How can you recognize an enzyme? How does pH affect enzyme activity? How does temperature affect enzyme activity?

Enzyme Lab

Homework: Prepare for Lab tomorrow!