1. Thursday, March 11

2.  Cellular respiration  Harvesting energy from glucose using O 2  Use of O 2 = aerobic  C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O + energy  Accomplished via ~20 rxns (product of one is reactant for next, all catalyzed)

3.  “Glucose is oxidized to carbon dioxide and oxygen is reduced to water.”  C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O + energy  Hydrogen atoms carry electrons away from carbon atoms in glucose to oxygen atoms

4.  L oss of e lectrons = o xidation  G ain of e lectrons = r eduction An electron transfer always involves an oxidation, reduction  “ redox ”

5. LOGIC: 1. When the hydrogen atoms form covalent bonds with oxygen, the shared electron pairs are closer to the oxygen nucleus (oxygen is more electronegative than carbon is). 2. An electron occupying energy level closer to nucleus has less potential energy (similar to a skydiver closer to earth).

6. LOGIC: 3. So, electrons that move from less electronegative carbon to more electronegative oxygen lose potential energy and achieve a LESS ordered state (not intuitive but whatever). 4. The decrease in potential energy coupled with an increase in entropy (electrons being closer to nucleus) causes a decrease in free energy and an overall exergonic reaction.

8.  C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O + energy  Also an oxidation reaction

9.  C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O + energy  Overall change = decrease in potential energy = increase in entropy  “Downhill process”  Energy= heat + light

10.  Glucose and O 2 stable on their own  Presence of enzymes!  Lower E A  Obligate anaerobes  Obligate aerobes  Facultative anaerobes

11.  C 6 H 12 O 6 + O 2  6CO 2 + 6H 2 O + energy