BIOL 112 Lecture Notes - Lecture 34: Electron Transport Chain, Negative Feedback, Photon
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o!Two major pathways: lactic acid fermentation and ethanol fermentation
o!Lactic acid fermentation:
!!Pyruvate is reduced by the enzyme lactate dehydrogenase to
produce lactate (going backwards in a way)
!!Which produces more NAD+
!!The end product is lactic acid (lactate), high-energy molecule but it
stops there
!!This results in sore muscles (so when you use your muscles a lot,
eventually supply of O2 dwindles, so muscles do this)
o!Alcoholic fermentation:
!!Occurs in yeast, some plant cells
!!Requires two reactions
!!First, decarboxylation reaction (results in aldehyde ethanal)
!!Ethanal is then reduced into ethanol
!!End result: just like 2 ATP, lol (incomplete combustion)
!!So obviously less efficient than cellular respiration, more of a short-
term solution (long-term for yeast I guess)
6.5Metabolic pathways
•!Glucose isn't the only thing involved in metabolic reactions
•!Other products enter metabolic pathways, all interrelated
•!Catabolic products enter the pathways at different steps
•!Intermediate products leave at some steps to be involved in other reactions
•!Lots of hustle and bustle
•!Catabolic interconversions:
o!Polysacchardies are hydrolysed to glucose
o!Lipids broken down to glycerol and fatty acids (eventually acetyl CoA)
o!Proteins hydrolysed to amino acids, feed into glycolysis or krebs cycle
o!Most are reversible
•!Anabolic interconversions:
o!Gluconeogenesis: glucose formed from citric acid cycle and glycolysis
intermediates, for storage (undo previous reactions?)
o!Acetyl CoA can be used to make fatty acids