Fundamentals of Biology: Lecture Outline - Chapter 6 - Metabolism
Energy:
Potential Energy
Kinetic Energy
Thermal Energy
Chemical Energy
- kilocalorie = amount of energy to heat 1000 grams of water from 14.5-15.5 deg. C
Cells use energy to -
Laws of Thermodynamics
First Law: total amount of energy
Second Law of Thermodynamics: spontaneous direction
Entropy = amount of disorder
*Life does not violate this law because the earth is not a "closed system"
Source of energy for life =
One-way flow of energy
Exergonic "energy out" reactions
Endergonic "energy in" reactions
The Role of Adenosine Triphosphate:
- main energy carrier
- "earn" ATP in
- "spend" ATP during
ATP/ADP cycle
Oxidation/Reduction Reactions:
- electron transfers
Oxidation = removal
Reduction = addition
Metabolic Pathways
Chemical equilibrium
- any reversible reaction runs spontaneously toward equilibrium
- Note: amount of products and reactants
Law of Conservation of Mass
Electron Transfer Chains
- enzymes + coenzymes
- one molecule becomes oxidized, the next in line
- electrons enter
Enzymes:
- Speed up
- Reused
- Act on both the forward + reverse
- Very selective
Mechanisms of Enzyme Action
- Help substrates get together
- Orient substrates in correct positions
- Shut out water
- Induce changes
"Induced Fit" Model
Cofactors
- speed up reaction or carry electrons
Allosteric Control
- some enzymes have control sites in addition to active sites
- Activator - binds to allosteric site
- Inhibitor
Feedback Inhibition
- end product inhibits enzyme in pathway
Factors Influencing Enzyme Activity
Temperature
pH
- pH of stomach = 1-2
- pH of small intestine =
Beer, Enzymes and your Liver (6.8 Focus on Health)
Alcoholic hepatitis
Alcoholic cirrhosis
Bioluminescence - a visible sign of metabolism
Enzyme = luciferase
Clinical application
Review - Chapter 6 (p. 112-113)
Review questions 2-11
Self quiz 1-9