1. Chapter 8 An Introduction to Energy & Metabolism (Pages 141-159) Topics: Thermodynamic Laws Catabolism & Anabolism (metabolism) Exergonic vs. Endergonic Reactions Free Energy ATP Cycle & Energy Coupling Enzyme (structure & function)

2. Main Topics to Cover-Ch. 8 Potential vs. Kinetic Energy First Two Laws of Thermodynamics Entropy, Enthalpy, and Free Energy Endergonic vs. Exergonic Reactions Anabolism & Catabolism = Metabolism Energy Coupling: Oxidation/Reduction ATP; Structure & Function Enzymes Structure & Function (Lab #6) -allosteric, feedback mechanisms, inhibitory sit.

3. Energy is defined as the capacity to do work All organisms require energy to stay alive Energy makes change possible Energy is the capacity to perform work

4. Living cells are compartmentalized by membranes Membranes are sites where chemical reactions can occur in an orderly manner Living cells process energy by means of enzyme-controlled chemical reactions ENERGY AND THE CELL

5. Kinetic energy is energy that is actually doing work Potential energy is stored energy Figure 5.1A Figure 5.1B

6. Thermodynamics Energy (E)~ capacity to do work; Kinetic energy~ energy of motion; Potential energy~ stored energy Thermodynamics~ study of E transformations 1st Law: conservation of energy; E transferred/transformed, not created/destroyed 2nd Law: transformations increase entropy (disorder, randomness) Combo: quantity of E is constant, quality is not

7. First law of thermodynamics Energy can be changed from one form to another –However, energy cannot be created or destroyed Two laws govern energy conversion Figure 5.2A

8. Second law of thermodynamics Energy changes are not 100% efficient –Energy conversions increase disorder, or entropy –Some energy is always lost as heat Figure 5.2B

9. Metabolism/Bioenergetics Metabolism: The totality of an organism’s chemical processes; managing the material and energy resources of the cell Catabolic pathways: degradative process such as cellular respiration; releases energy Anabolic pathways: building process such as protein synthesis; photosynthesis; consumes energy

10. Equation Used to Determine Free Energy of a System (see Pg. 145)  G =  H - T  S G: Quantity of Free Energy H: Enthalpy = System’s Total Energy (chemical Bond energy) T: Temperature (absolute temp. in Kelvin units) S: Entropy = Disorder of the system Spontaneous Reaction =  G will be negative (energy is released ie. Exergonic.) Non spontaneous Reaction (Endergonic)  G will be positive. What happens when  G is ZERO ???

12. Free Energy Free energy: portion of system’s E that can perform work (at a constant T) Exergonic reaction: net release of free E to surroundings Endergonic reaction: absorbs free E from surroundings

13. ATP & Energy Coupling See Pgs. 147-150

14. ATP is thought as the energy “currency” of a cell In cellular respiration, some energy is stored in ATP molecules ATP powers nearly all forms of cellular work ATP molecules are the key to energy coupling ATP shuttles chemical energy within the cell

15. General Facts about ATP Human use about 99 lbs of ATP each day @rest Every second 10 million ATP’s are made from ADP Bacteria has about a one-second supply of ATP

16. Energy Coupling & ATP Energy coupling: use of exergonic process to drive an endergonic one (ATP) Adenosine triphosphate (nucleotide w/3 PO 4 ’s) ATP tail: high negative charge ATP hydrolysis: release of free Energy Phosphorylation: binding of the released phosphate to another molecule

17. The ATP cycle Figure 5.4C Energy from exergonic reactions Dehydration synthesis Hydrolysis Energy for endergonic reactions

18. The Hydrolysis of ATP

19. When the bond joining a phosphate group to the rest of an ATP molecule is broken by hydrolysis, the reaction supplies energy for cellular work.  G = -32 KJ/mol (-7.6 Kcal/mol) Figure 5.4A Phosphate groups Adenine Ribose Adenosine triphosphate Hydrolysis Adenosine diphosphate (ADP) Energy

20. Example of Energy Coupling w/ATP Forming the Disaccharide Sucrose involves: glucose + fructose → sucrose (  G = +27 KJ/mol) ENDERGONIC Reaction Couple w/hydrolysis of ATP (  G = - 32KJ/mol) Occurs in a couple of reaction steps: Reaction#1: Glucose + ATP → glucose-P + ADP **glucose has been phosphorylated **ATP has been hydolyzed Reaction #2: Glucose-P + fructose → Sucrose + Pi (Pi is a low energy inorganic phosphate)

21. How ATP powers cellular work Figure 5.4B Reactants Potential energy of molecules Products Protein Work

22. Three Functions of ATP

23. Enzymes: Structure & Function See Pgs. 150-157

24. For a chemical reaction to begin, reactants must absorb some energy –This energy is called the energy of activation (EA) –This represents the energy barrier that prevents molecules from breaking down spontaneously Enzymes speed up the cell’s chemical reactions by lowering energy barriers

25. Enzymes Catalytic proteins: change the rate of reactions w/o being consumed Free E of activation (activation E): the E required to break bonds Substrate: enzyme reactant Active site: pocket or groove on enzyme that binds to substrate Induced fit model

26. A protein catalyst called an enzyme can decrease the energy barrier E A barrier Reactants 1Products2 Enzyme Figure 5.5A

27. Enzymes are selective –This selectivity determines which chemical reactions occur in a cell A Specific Enzyme Catalyzes each Cellular Reaction

28. How an Enzyme Works-Sucrase

29. How Enzymes Work http://www.ekcsk12.org/science/aplabrevie w/lab02.htmhttp://www.ekcsk12.org/science/aplabrevie w/lab02.htm **Description of Enzyme Lab Lab Simulation: http://bioweb.wku.edu/courses/Biol114/enzy me/enzyme1.asp

30. Lab #2- Enzyme Catalysis w/Catalase Three Parts to the lab: Establish Baseline Amount of H 2 O 2 Uncatalyzed Decomposition of H 2 O 2 Time Trials w/Catalase to determine Rxn rate Procedure: –10 ml H 2 O 2 in a beaker –1.0 ml (H 2 O or Catalase) –10 ml 1 M H2SO4 –Mix well –Take a 5 ml sample and titrate in KMnO 4 (use the sm pipette) –Read Initial and final measurements on buret –Record Data

31. Enzyme activity is influenced by –temperature –salt concentration –pH Some enzymes require non-protein cofactors such as: Fe, Zn, Cu, etc. The Cellular environment affects enzyme activity

32. Effects on Enzyme Activity Temperature pH Cofactors: inorganic, nonprotein helpers; ex.: zinc, iron, copper Coenzymes: organic helpers ex. vitamins

33. Enzyme Inhibitors Irreversible (covalent); reversible (weak bonds) Competitive: competes for active site (reversible); mimics the substrate Noncompetitive: bind to another part of enzyme (allosteric site) altering its conformation (shape); poisons, antibiotics

34. Inhibitors interfere with enzymes –A competitive inhibitor takes the place of a substrate in the active site –A noncompetitive inhibitor alters an enzyme’s function by changing its shape Enzyme inhibitors block enzyme action Substrate Enzyme Active site NORMAL BINDING OF SUBSTRATE Competitive inhibitor Noncompetitive inhibitor ENZYME INHIBITION Figure 5.8

35. Competitive & Noncompetitive Inhibitors

36. Certain pesticides are toxic to insects because they inhibit key enzymes in the nervous system Many antibiotics inhibit enzymes that are essential to the survival of disease-causing bacteria –Penicillin inhibits an enzyme that bacteria use in making cell walls Some Pesticides and Antibiotics inhibit Enzymes

37. Allosteric Enzymes-How they Work

38. Enantiomners: Left & Right handed Molecules

39. Pg. 62 Chiral Molecules “Optical Isomers”

40. Isomers Molecules with same chemical formula (# of atoms) but different structure. Structural isomers: Ex. C 4 H 10 Butane and isobutane (has two isomers)(See pg. 61) **C 20 H 42 has 366,319 different isomers (video) Geometric Isomers: arrangement and number of atoms are the same but different in their spatial arrangement. **commonly referred to “cis” and “trans” (see pg. 62) **Observed commonly with double bonded substances. Enantiomers: molecules that are mirror images of each other. **There are left and right hand forms. **Assymetric and cannot be superimposed with each other. (See pg. 47)

41. Feedback Inhibition

42. Video #2- Metabolism (Ch. 8) 1)Name the American Olympiad profiled in this video. What condition did she have? 2)What are the two major reasons why cells use energy? 3)What unique metabolic process does Dr. Margo Haygood discuss in the video? Name the enzyme used for this process. 4)Which two laws of thermodynamics are summarized by Dr. Saltman & Dr. Haygood? 5)Briefly explain how enzymes are able to speed up reactions based on the information from the video. Describe the mechanisms that regulate enzyme activity. ***Remember to Write the Title for each segment and FIVE key statements from each section

43. Energy Transfer in Redox Reactions See Pgs. 161-162

44. Redox-Defining Terms Oxidation = Electrons are lost (Hydrogens lost) Reduction = Electrons are gained (Hydrogens gained) These two reactions are complementary and occur simultaneously (they must go together) Electrons cannot exist in a free state, they must be associated with a molecule This process allows electrons to be transferred from one molecule to another Often occur in a series Essential for cellular respiration & Photosynthesis

45. Electrons are transferred by a carrier molecule by the hydrogen atom Common electron carrier: NAD+ NAD+ is Nicotinamide adenine dinucleotide When NAD+ is reduced it gains an electron and becomes reduced. The electron losses some of its free energy during the transfer Expressed as: X-H 2 + NAD+  X+ NADH + H + (oxidized) (reduced)

46. Other Electron Carriers (hydrogen acceptors) NADP + (see in photosynthesis) FAD + (see in the Kreb cycle for cellular respiration) Cytochromes – embedded in membranes **Remember that: Reduced state more free energy vs. Oxidized state which has less free energy

47. The End of Chapter 8

48. Fireflies use light, instead of chemical signals, to send signals to potential mates Females can also use light flashes to attract males of other firefly species — as meals, not mates Cool “Fires” Attract Mates and Meals

49. The light comes from a set of chemical reactions, the luciferin- luciferase system Fireflies make light energy from chemical energy Life is dependent on energy conversions