Bio 3 – Enzyme Lab Part 1: Enzymes, cheese making, and fat digestion An enzyme

Cheese making takes an hour an a half Must begin the procedure before the lecture Slowly heat the milk to 32°C. Stir occasionally. Add 1 ml of enzyme and stir for one minute. Allow the beaker to sit undisturbed for about 30 minutes.

Globular proteins that facilitate reactions Enzymes: Globular proteins that facilitate reactions Many reactions require energy to start Enzymes reduce the energy required Enzymes are Biological Catalysts Initiate and increase the rates of reactions Not consumed or altered Coordinate production of molecules with need Specific to a particular substrate

Substrate specificity is based on shape Unique surface shape Unique electromagnetic properties

How enzymes work Decrease Energy of Activation (EA) to start reactions Simple example: spark plugs reduce EA EA is absorbed by reactants Destabilizes their bonds Increases their reactivity Enzymes do not supply energy “Induced fit” lowers need for EA Squeezes and aligns substrate(s) Active site

Example: enzyme-mediated reaction

Sucrase enzyme (-ase indicates enzyme) 1 3 2

1 Sucrase catalyzes hydrolysis of sucrose (substrate) 3 2

Produces glucose & fructose (products) 1 Produces glucose & fructose (products) 3 2

1 3 2

1 3 2

1 3 2

1 3 2

1 3 2

Enzymes can be involved in: 1) Degradation: previous sucrase example 2) Synthesis: 3) Transformation:

Enzymes work best in optimal conditions Can undergo > 1 million reactions / second Thermal optimum Excessive cold or heat decreases activity Cold slows molecular motion Too much heat DENATURES enzymes Breaks hydrogen bonds that hold its shape

Gastric enzymes pH optimum Neutral (pH = 7) for many human enzymes Exceptions: Gastric enzymes Enzymes of organisms in alkaline environments Acid rain slows enzymes of aquatic organisms

Read pages 41-43 of the lab manual, then begin cheese making.

Replicate fat digestion in a test tube Part 2: Lipid digestion Today’s exercise: Replicate fat digestion in a test tube Same process occurs in your intestine Add the following to each tube: Tube 1: 3 ml of litmus cream + 6 ml of distilled water. Tube 2: 3 ml of litmus cream + 3 ml of distilled water + 3 ml of bile solution. Tube 3: 3 ml of litmus cream + 3 ml of distilled water + 3 ml of lipase solution. Tube 4: 3 ml of litmus cream + 3 ml of bile solution + 3 ml of lipase solution. Groups A-D will incubate at different temperatures for 1 hr.

Lipid digestion occurs in your small intestine Liver Pancreas (with lipase) Gall bladder (with bile) Small intestine (doudenum)

Lipid digestion by hydrolysis

Fatty acids disassociate in an aqueous solution Carboxyl functional group = HO-C-CH2-CH2-CH2-CH2-CH2 O = O - O-C-CH2-CH2-CH2-CH2-CH2 H+ Hydrogen ion Presence of H+ ion changes pH