October 16, 2012 AP Bio Notes

(Heads up! Qu-est: Oct. 23, 2012)

Step by step through Electron Transport Chain CONTINUED...

        3. The 3 Protein Complexes use the power of the electrons to pump protons into the INTER MEMBRANE SPACE creating a Proton Gradient. The Protons diffuse back through ATP SYNTHASE to power the synthesis of 32 more ATP's.
                 *(0 NADH, 0 FADH2, 36 ATP, 6 CO2, 6 H20)

The electrons bond w/ protons to O2 forming H20.
                 4e- + 4H+ + 02 => 2 H20 
Without O2 as an electron acceptor, everything that happens in a MITOCHONDRIA stops. 

II. Anaerobic Respiration: Respiration in the absence of 02

    A. Other electron acceptors used by bacteria.
        1. Methanogens: use CO2 as their terminal electron acceptor (TEA) and give off Methane (CH4)
        2. Sulfur Bacteria: use SO4 as their TEA and give off H2S (Hydrogen Sulfide)

    B. Fermentation: cycle glycolysis in order to keep making 2 ATP's per glucose.
        In order for this to happen: a cell must regenerate NAD because when NAD runs out, the reactions that recover the 2 lost ATP's and then add 2 more, cannot happen.
        1. Lactic Acid Fermentation: happens when eukaryotic cells run out of oxygen. Our cells convert pyruvate into lactic acid and this step regenerates NAD+. 
        2. Alcohol Fermentation: yeasts. When they run out of O2, convert Pyruvate to Acetaldehyde (losing a Co2) and then they reduce it to Ethanol regenerating NAD+.
                 (example: Beer)