1. Energy and Metabolism Notes

2. Energy (E) Kinetic E (KE) - energy of movement. In Biology, this energy is usually the movement of electrons or protons. Potential E (PE) –energy of position. Usually in the chemical bonds associated with those electrons and protons. For living organisms, the chemical E of life is found in chemical bonds. The processes of Digestion and Cellular Respiration release the E for use by cells.

3. Thermodynamics First Law of Thermodynamics – Law of Conservation of Energy – energy can’t be created or destroyed, only transferred or transformed. Second Law of Thermodynamics – entropy increases - entropy – measure of disorder

4. Gibbs Free Energy Think of free energy as available energy. ∆G = ∆H-T∆S Free energy – (G) Enthalpy – total energy of a system (H) Temperature – (T) Entropy – measure of disorder in system (S)

5. Gibbs Free Energy ∆G = ∆H-T∆S ∆G measured in kcal/mole H  G  S  G  T  G  If G<O it is a exergonic reaction – energy is available G>0 it is an endergonic reaction - energy is stored (unavailable) G=0 it is at equilibrium

6. Life requires Free Energy To be Organized To Grow To Reproduce

7. Life requires order and a lack of entropy. This is accomplished by coupling processes that increase entropy with processes that decrease entropy Ex: cellular respiration with photosynthesis Energy input must exceed free energy loss.

8. Metabolism – the sum total of all reactions occurring in an organism. 2 Components: Catabolism – breaking down molecules (hydrolysis reaction) - releases energy stored in the chemical bonds - exergonic (energy/heat released) - Ex: Cellular Respiration Anabolism – assembling molecules (dehydration synthesis reaction) - uses energy to form chemical bonds - endergonic (absorbs energy) - Ex: Photosynthesis

10. Cellular Respiration - increase in entropy - exergonic reaction - ∆G<0 – energy is released - energy must be put in to start the reaction - Activation Energy

11. Photosynthesis -Endergonic reaction -∆G >0 – energy is stored -Activation energy from the sun

12. ATP Energy molecule Adenosine triphosphate made from ribose and adenine (nitrogenous base) Broken down into Adenosine diphosphate, releasing energy ATP  ADP + Pi ∆G<0 release energy ADP + Pi  ATP ∆G>0 store energy

13. Metabolism and Body Size Large animals have a much lower metabolism than small animals. – A smaller animal loses more energy as heat, so it must increase its metabolism to accommodate (homeostasis) Instead, ectotherms use the environment to control their temperature.

14. Energy is used for daily processes (active transport of molecules into and out of cells, nerve signals, muscle contractions) Energy is also used for growth and development, maintaining order and homeostasis. Extra energy can be used for reproduction.

15. Reproductive strategies Different organisms have different reproductive strategies to best utilize free energy. – If there isn’t enough extra energy, the organism won’t reproduce. Some organisms only reproduce in certain seasons. Some organisms put their energy into raising their young and reproduce in small numbers. Some organisms put their energy into reproducing in large numbers and don’t work to raise their young.

16. Disruption Disruption in free energy in an organism leads to DEATH Disruption in free energy can lead to changes in a population or an ecosystem – Changes in one level can affect the other levels. – Changes in the environment can affect the different levels.