1. Introductory Questions #6
Explain how potential energy is different from kinetic energy. What are some ways we can measure energy?
2) Define each variable in the equation:
∆G = ∆H – T ∆S
3) How much energy expenditure will Trent Samaha have to exert to ask Ema Armstrong to Homecoming? (Ema please go outside to answer the question…NOW!)♥
3.5)What is the difference between an exergonic reaction and an endergonic reaction?
How is ATP associated with coupled reactions? What purpose does it serve?
How is an electron carried from one molecule to the next? Name a molecule that can carry an electron.

2. 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)

3. 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.

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

5. ENERGY AND THE CELL 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

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

7. Thermodynamics Combo: quantity of E is constant, quality is not
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

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

9. 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

10. 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

11. Equation Used to Determine Free Energy of a System
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 ???

13. 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

14. ATP & Energy Coupling
See Pgs.

15. ATP shuttles chemical energy within the cell
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

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

17. Energy Coupling & ATP
Energy coupling: use of exergonic process to drive an endergonic one (ATP)
Adenosine triphosphate (nucleotide w/3 PO4’s)
ATP tail: high negative charge
ATP hydrolysis: release of free Energy
Phosphorylation: binding of the released phosphate to another molecule

18. Introductory Video for Chapter 8
“Metabolism”
Name the American Olympiad profiled in this video. What condition did she have?
What are the two major reasons why cells use energy?
What unique metabolic process does Dr. Margo Haygood discuss in the video? Name the enzyme used for this process.
Which two laws of thermodynamics are summarized by Dr. Saltman & Dr. Haygood?
Briefly explain how enzymes are able to speed up reactions based on the information from the video. Describe the mechanisms that regulate enzyme activity.

19. The Hydrolysis of ATP

20. Adenosine triphosphate Adenosine diphosphate (ADP)
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)
Adenine
Phosphate groups
Hydrolysis
Energy
Ribose
Adenosine triphosphate
Adenosine diphosphate (ADP)
Figure 5.4A

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

22. 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)

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

24. Three Functions of ATP

25. Enzymes: Structure & Function
See Pgs

26. Lab #3- Enzyme Catalysis w/Catalase
Three Parts to the lab:
Establish Baseline Amount of H2O2
Uncatalyzed Decomposition of H2O2
Time Trials w/Catalase to determine Rxn rate
Procedure:
10 ml H2O2 in a beaker
1.0 ml (H2O or Catalase)
10 ml 1 M H2SO4
Mix well
Take a 5 ml sample and titrate in KMnO4
Read Initial and final measurements on buret
Record Data

27. Enzymes speed up the cell’s chemical reactions by lowering energy barriers
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

28. 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

29. A protein catalyst called an enzyme can decrease the energy barrier
EA barrier
Enzyme
Reactants 1
Products 2
Figure 5.5A

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

31. How an Enzyme Works-Sucrase

32. Lab Simulation: How Enzymes Work
**Description of Enzyme Lab
Lab Simulation:

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

34. 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

35. Enzyme inhibitors block enzyme action
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
Substrate
Active site
Enzyme
NORMAL BINDING OF SUBSTRATE
Competitive inhibitor
Noncompetitive inhibitor
ENZYME INHIBITION
Figure 5.8

36. Competitive & Noncompetitive Inhibitors

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

38. Some Pesticides and Antibiotics inhibit Enzymes
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

39. Allosteric Enzymes-How they Work

40. Feedback Inhibition

41. Introductory Questions #6
Explain how potential energy is different from kinetic energy. What are some ways we can measure energy?
2) Define each variable in the equation:
∆G = ∆H – T ∆S
3) What is the difference between an exergonic reaction and an endergonic reaction?
How is ATP associated with coupled reactions? What purpose does it serve?
How is an electron carried from one molecule to the next? Name a molecule that can carry an electron.

42. Introductory Questions #7
Name three ways that enzyme activity can be measured as mentioned in your lab guidesheet.
Explain how the reactivity of pepsin is different from trypsin. (see pg. 154)
Give an two examples of a cofactor and two examples of a conenzyme. How are they different?
How is a competitive inhibitor different from a non-competitive inhibitor?
What is an allosteric enzyme?

43. Energy Transfer in Redox Reactions
See Pgs

44. Redox-Defining Terms Oxidation = Electrons are lost
Reduction = Electrons are 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-H2 + 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. Cool “Fires” Attract Mates and Meals
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

48. 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