1. Unit 3 Cellular Energetics Chapters 6, 7, and 8

2. I. Thermodynamics Metabolism Cell’s capacity to Acquire energy Build Break apart Release substances Defining Energy Potential Energy Kinetic Energy Heat (Thermal) Energy Chemical Energy A. Definition = the study of energy transformations

3. Total Energy Content Energy content of any system with the environment remains constant

4. B. First Law of Thermodynamics  “energy can be neither created nor destroyed, but is easily transformed” C. Second Law of Thermodynamics  “with every energy transformation entropy increases and free energy decreases in a closed system” 1. Entropy = disorder, randomness 2. Free energy = energy available to do work (instability)(G) Therefore, to stay organized living systems must have an external source of energy

5. 2.More on free energy The term free does not mean that there is no cost to using this energy! It means that the energy is available! H symbolizes total energy, S symbolizes entropy and T is temperature G = H - TS Temperature amplifies the entropy, causing more random movement of molecules!

7. Count the Number of F’s in the following text: FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS How Many?3? WRONG, THERE ARE SIX!!! LOOK AGAIN.

9. II. Reactions A. Exergonic reactions (  G is negative) – “energy out”Exergonic reactions Greater instability Lesser instability B. Endergonic reactions (  G is positive) – “energy in”Endergonic reactions Lesser instability Greater instability C. ATP* is the energy shuttle within the cell *Adenosine triphosphate

10. Exergonic Endergonic

11. Non- spontaneous; energy-requiring

16. Phosphorylation Transfer of a phosphate group to a molecule

17. D. Electron Transfers: Oxidation- Reduction Reactions Oxidation - removal of electrons Reduction - addition of electrons

19. E. Which way will a reaction run? Nearly all chemical reactions in cells are reversible A + B C SubstratesProduct

20. F. Chemical Equilibrium High reactant concentration - runs strongly forward Equilibrium - rate of forward and back reactions the same High product concentration - runs strongly in reverse

22. III. Enzyme Structure and Function Catalysts speed the rate of chemical reactions Not permanently altered or used up Reversible reactions Selective for the substrates

23. A.Activation energy (E A ) Energy required to activate a substance to enter into a reaction

25. 16001700 1. Sally likes 225 but not 224; she likes 900 but not 800; she likes 144 but not 145. Which does she like: 2. Which of the designs best completes the following sequence? Answer = 1600 (Perfect squares) Answer = 1 st one 3. Look at the drawing. The numbers alongside each column and row are the total of the values of the symbols within each column and row. What should replace the question mark? 2323 2525 2828 3030 3232 23, 25, 28, 30, or 32 Answer = 25

26. 1. Active site characteristics a. Specificity b. Reusability c. Induced fit 2. Mechanisms to lower E A a. Alignment of functional groups (anabolic) b. Stressing(bending) bonds (catabolic) c. Microenvironment formation (pH) 3. Average rate = 1000 reactions/sec. 4. Enzyme has no effect on direction of the reaction!! enzyme + substrate(s) enzyme-substrate complex enzyme + product(s) B. Enzyme action

28. Sucrose + water Sucrase Glucose + Fructose

30. C. Factors affecting enzyme activity 1. Concentration of enzyme, substrate, or product 2. Temperature 3. pH a.Pepsin (pH 2) in stomach b. Trypsin (pH 8) in small int.

31. 4. Cofactors - nonproteins that temporarily or permanently bind in the active site a.Inorganic – ionic Zn, Fe, or Cu b.Coenzymes - organic, many B vitamins NAD + and FAD are derived from vitamins

33. 5. Enzyme Inhibitors a. Competitive vs noncompetitive, i.e. within the active site or not within it b. Reversible (control of reactions) vs irreversible (poisons such as penicillin in bacteria)

34. 6. Allosteric regulation a. Involves both inhibitor and activator molecules b. “Dock” in specific, nonactive site receptors (noncompetitive) c. Enzymes affected are usually composed of more than one polypeptide chain

35. 7. Cooperativity

36. 8. Feedback Inhibition - Control mechanism a. Shutting down of activity b. Product produced shuts down reaction Binds to allosteric site