1. Ground Rules of Metabolism Chapter 6 Part 1

2. Impacts, Issues: A Toast to Alcohol Dehydrogenase  In the liver, alcohol dehydrogenase helps break down toxic alcohols, but at the expense of liver function and energy metabolism( 12oz beer, 5oz wine, 1oz of vodka all have the same effects on the liver)

3. Energy Disperses  First law of thermodynamics Energy is neither created nor destroyed (goes back into the evnrionment as heat), but can be transferred from one form to another  Second law of thermodynamics Entropy (a measure of dispersal of energy in a system) increases spontaneously ( Ex.Heat/pan) Energy is converted from a more concentrated form to a less concentrated form when energy is transferred.

4. One Way Flow of Energy  The total amount of energy available in the universe to do work is always decreasing Each time energy is transferred, some energy escapes as heat; thermal energy decreased (not useful for doing work) Potential energy can be converted to kinetic energy, ATP in muscle cells (mechanical energy) gives up potential energy to contractile units, chemical energy is converted to kinetic energy.

5. Energy In, Energy Out  Reaction A chemical change that occurs when atoms, ions, or molecules interact  Reactant Atoms, ions, or molecules that enter a reaction  Product Atoms, ions, or molecules remaining at the end of a reaction

6. Fig. 6-6, p. 96 ReactantsProducts 2 H 2 (hydrogen) + O 2 (oxygen) 2 H 2 O (water) 4 hydrogen atoms 2 oxygen atoms

7. Reactions Require or Release Energy  We can predict whether a reaction requires or releases energy by comparing the bond energies of reactants with those of products  Endergonic (“energy in”) Reactions that require a net input of energy (Ex. Photosynthesis)  Exergonic (“energy out”) Reactions that end with a net release of energy (Ex. Cellular Respiration)

8. Why the World Doesn’t Go Up in Flames  Activation energy The minimum amount of energy needed to get a reaction started or to proceed on its own.

9. ATP – The Cell’s Energy Currency  ATP (adenosine triphosphate) A nucleotide with three phosphate groups Gives up a phosphate group and energy to other molecules Primes stable molecules to react (Ex. PGA gives up a P group to ADP Made by all cells  Phosphorylation A phosphate-group transfer

10. Fig. 6-9b, p. 97 adenineAMPADPATP ribose PPP B The molecule is called ATP when it has three phosphate groups. After it loses one phosphate group, the molecule is called ADP (adenosine diphosphate); after losing two phosphate groups it is called AMP (adenosine monophosphate).

11. Animation: Mitochondrial chemiosmosis

12. 6.3 How Enzymes Make Substances React  Enzyme A catalyst that makes a reaction occur much faster than it would on its own Enzymes are not consumed or changed by participating in a reaction Most are proteins (organic molecules, some are RNA Are very specific and have special shapes  Substrate The specific reactant acted upon by an enzyme

13. How Enzymes Work  Enzymes lower the activation energy required to bring on the transition state, when substrate bonds break  Active sites A groove in the structure of the enzyme where substrates bind and reactions proceed

14. Fig. 6-11, p. 98 Transition state Activation energy without enzyme Activation energy with enzyme Reactants Free energy Products Time

15. Reactants Free energy Time Fig. 6-11, p. 98 Products Transition state Activation energy with enzyme Activation energy without enzyme Stepped Art

16. Animation: Activation energy

17. Mechanisms of Enzyme-Mediated Reactions  Binding at enzyme active sites may bring on the transition state by four mechanisms Helping substrates get together they will react Orienting substrates in positions that favor reaction Inducing a fit between enzyme and substrate (induced fit model- enzyme sqeezes the substrate)

18. Effects of Temperature, pH, and Salinity  Raising the temperature boosts reaction rates by increasing a substrate’s energy But very high temperatures denature enzymes Optimum temperature (37-40°celcius)  Each enzyme has an optimum pH range (6-8)

19. Help from Cofactors  Cofactors Atoms or molecules (other than proteins) that are necessary for enzyme function  Coenzymes Organic cofactors such as vitamins Examples: NAD and FAD