Proteins Structure: Polypeptide chains Consist of peptide bonds between 20 possible amino acid monomers Have a 3 dimensional globular shape

Functions of Proteins I. Structural materials, including keratin (_____________________) and collagen (______________________________).

II.Binding, such as ________________ that bind specifically to foreign substances to identify them to the body's immune system.

III.Specific carriers, ________________________________ _______________________________, and blood proteins, such as hemoglobin, that carry oxygen, iron, and other substances through the body.

IV. Contraction, such as ____________________ fibers that interact in muscle tissue. V. Signaling, including _____________________ that regulate sugar levels in blood.

VI. ENZYMES

Free Energy  G Energy is stored in bonds within molecules There is also unavailable energy present in the molecule that cannot be used because it is energy of disorder Free energy is the energy that is available energy

Types of reactions See Page 147 in Raven, Johnson If  G is negative, then there was free energy released so the products of the reaction have less energy than the reactants = _____________________ If  G is positive, then the products of the reaction contain more energy than the reactants and energy was absorbed = _____________________

Activation Energy All chemical reactions need energy to get started = Activation Energy ____________________________________ Higher temperatures can increase the reaction rate, but too high can be dangerous so… ____________________________________ ____________________________________ ____________ Enzymes are specific, so there is a different enzyme for each chemical reaction

Is this reaction exergonic or endergonic?

What are Enzymes? Catalysts change the rate of the reaction without being altered themselves. _____________________________. _______________________, whose three dimensional shape allows for their ability to react specifically.

Enzyme / Substrate Relationship: What is the substrate? ____________________________________ ____________________________________. Enzymes are substrate specific. ____________________________________ ____________________________________. These principles lead to the “Induced Fit” model of enzyme action.

The Active Site The active site is where ___________________________________ ___________________________________. Most enzyme-substrate interactions are the result of weak bonds. The active site may cause the enzyme to hold onto the substrate in a very specific way. The active site may provide a micro- environment ___________________________________ ___________________________________

Rate of Reaction: Enzyme Kinetics I.Time Initially, substrate concentration is high = ________________________________ Eventually substrate concentration decreases and __________________________________ The enzyme has more products binding to the active site = __________________________________ __________________________________

Feedback Inhibition

Rate of Reaction: Enzyme Kinetics II.Temperature Up to 40 o C, the reaction rate increases because more heat = more motion, collisions, more products Above 40 o C, ______________________________ ______________________________

Rate of Reaction: Enzyme Kinetics III.pH Different enzymes have ______________________________ Adding H + to solution or removing H + can __________________________ in the enzyme causing the enzyme to unfold or denature

Enzyme Activity Temperature pH Enzyme Concentration Substrate Concentration

Rate of Reaction: Enzyme Kinetics IV. Cofactors/Coenzymes Non-protein molecules that help enzymes function. Bind to active site to enhance enzymatic reactions or can bind to the substrate. Cofactors may be inorganic metals such as zinc, iron, or copper. Coenzymes are organic cofactors (e.g. vitamins)

Rate of Reaction: Enzyme Kinetics V.Free Radicals Produced when our bodies undergo aerobic respiration Drug and alcohol use can increase free radicals Can cause enzymes to denature Certain foods containing antioxidants can reduce free radicals by accepting the H +

Enzyme Inhibition Competitive inhibitors - ____________________________________ ____________________________________. Or, too much product can inhibit by binding to the active site so reactants can’t bind. Non-competitive inhibitors bind to the enzyme at sites called allosteric sites. ____________________________________ ____________________________________, and indirectly cause a change in the active site.

Feedback Inhibition

Allosteric Regulation Regulatory molecules that bind to the enzyme’s allosteric site changing the shape of the enzyme. Allosterically regulated enzymes have a quaternary protein structure. Each subunit of the enzyme has an active site and an allosteric site. Allosteric activators stabilizes the active site Allosteric inhibitors deactivates the active site.