1. Energy and Metabolism Chapter 8

2. Energy

3. Energy

4. Energy

5. Metabolism
All chemical reactions carried out by the cell

6. Metabolism Catabolic reactions:
Break down large molecules into smaller substances
Releases energy or is exergonic

7. Metabolism Anabolic reactions:
Synthesis of large molecules from smaller substances
Requires energy or is endergonic

8. Metabolism Biochemical pathways:
Reactions in a cell that occur in sequence
Product of one reaction becomes substrate in next reaction
Pathways are highly regulated & coordinated
Feedback inhibition:
End product of a reaction inhibits the pathway from producing more.

9. Energy

10. Energy Bioenergetics:
Analysis of how energy powers activities of living systems
Growth, order, reproduction, responsiveness & regulation
Require energy to happen

11. Energy Energy: Capacity to do work Kinetic energy Energy of motion
Potential energy
Energy of position or stored energy

12. Energy
Kinetic energy:
Potential energy:

13. Energy
Most of the work done by living organisms is the transformation of potential energy to kinetic energy
Thermodynamics: 
Study of energy “heat changes”

14. Energy Sun main source of energy
Energy from sun is used to combine smaller molecules to make larger molecules
Energy is then stored in the chemical bond

15. Energy Redox(oxidation-reduction) reactions:
Transfer of an electron or electrons
Play a key role in flow of energy in biological systems
An electron is passed from one atom to another energy is passed

16. Law of thermodynamics
Laws of thermodynamics govern all energy changes in the universe.
 First law of thermodynamics:
Energy cannot be created or destroyed
It can change from one form to another. (potential to kinetic)
Total amount of energy stays the same

17. First law In living organisms:
Eating transfers energy from bonds in food to organism
Potential energy is transferred to kinetic energy

18. First Law Heat: random motion of molecules
Heat can be lost during conversions
Sun replaces energy that is lost as heat

19. Second law Second law of thermodynamics:
Transformation of PE to heat (random motion of molecules).
Entropy (disorder) in universe is increasing

20. Second law Energy transformations tend to proceed spontaneously
Convert matter from a more ordered state to a less ordered
More stable state.

21. Second law Entropy(s): Disorder in a system Enthalpy (H): heat content
Free energy(G): Amount of energy available to do work in any system.
Amount of energy available to break & then make other chemical bonds

22. Second law G=Gibbs free energy G = H - TS (T=Kelvin temp)
G is positive than products have more energy than reactants
Due to more energy in bonds or less randomness
Endergonic reaction

23. Endergonic reaction

24. Second law G is negative products have less energy than reactants
H is lower (bond energy) or
S is greater- more randomness
Exergonic: any reaction that releases energy

25. Exergonic reaction

26. Exergonic reactions

27. Energy

28. ATP ATP powers energy requiring processes in cell
1. Chemical work (making polymers)
2. Transporting substances across the membranes
3. Mechanical work
Muscle movement, cilia

29. ATP Structure of ATP Ribose sugar Adenine
3 phosphate attached in a row

30. ATP

31. ATP

32. ATP ATP ADP Losses a inorganic phosphate Hydrolysis
7.3kcal/mole of energy is released.

33. Activation Energy Energy needed to initiate a reaction
Exergonic & endergonic reactions both require activation energy.
Reactions with higher AE tend to move forward more slowly

35. Enzymes Catalyst in living organisms
Large three-dimensional globular protein

36. Enzymes Substrate: Molecule that is going to undergo the reaction
Active sites: Specific spots on enzyme that substrates bind to.
Enzyme-substrate complex: enzymes are bound to substrates with a precise fit.
Induced fit: when the substrate causes the enzyme to adjust to make a better fit
E+S ES E + P

38. Enzymes Only small amounts are necessary Can be recycled Specific
Speeds up reactions
Different types of cells have different enzymes
Determine course of chemical reactions in the cell

39. Enzyme examples Lipase, protease Carbonic anhydrase
CO2 + H2O H2CO3
Lactate dehydrogenase
Lactate to pyruvate
Pyruvate dehydrogenase
Enzyme that starts the Kreb cycle

40. Enzymes Most enzymes are proteins
RNA has been shown to catalyze some reactions
Ribozymes:
RNA catalysts are specific & speed up reactions

41. Enzymes Factors that affect rate of enzyme-catalyzed reactions
1. Concentration of the enzyme & substrate
2. Factors that affect the 3-D shape of the enzyme
Temperature, pH, salt concentration & regulatory molecules

42. Enzymes Inhibitor: Binds enzyme & prevents it from working
Occurs at end of a pathway to stop reactions
Two types of inhibitors
Competitive
Noncompetitive

43. Enzymes Allosteric site: On/off switch for enzyme
Allosteric site usually at a different location than active site
Allosteric inhibitor:
Binds at allosteric site & stops enzyme activity
Activitors:
Bind & increases activity

45. Enzymes Cofactor: Assists enzyme function (Zn, Mg, Cu) Coenzymes:
Cofactors that are not proteins but are organic molecules
Help transfer electrons & energy associated with electrons
Vitamins are coenzymes
NAD+ is an important coenzyme