question number two … the “camel’s hump” From Stryer Biochemistry
“Compare the H2O yield from the complete oxidation of 1 gram of glucose with that of 1 gram of tripalmitoylglycerol. Relate these values to the evolutionary selection of the contents in a camel’s hump.”
“One gram of glucose (molecular weight 180.2) is equal to 5.55 mmol, and one gram of tripalmitoylglycerol (molecular weight 807.3) is equal to 1.24 mmol. The reaction stoichiometries indicate that 6 mol of H2O are produced per mole of glucose oxidized, and 49 mol of H2O per mol of tripalmitoylglycerol oxidized. Hence, the H2O yields per gram of fuel are 33.3 mmol (0.6g) for glucose, and 60.8 mmol (1.09g) for tripalmitoylglycerol. Thus, complete oxidation of this fat gives 1.82 times as much water as does glucose. Another advantage of triacylglycerols is that they can be stored in essentially anhydrous form whereas glucose is stored as glycogen, a highly hydrated polymer (p. 605). A hump consisting mainly of glycogen would be an intolerable burden -far more than the straw that broke the camel’s back!”]]>
Thank you for writing such an excellent article.
This sounds like a silly question, but I think there is a side to it that some people will find illuminating (I know I will). That is, when you lose weight, where does it go? Everyone talks about calories in/calories out. Sure, that’s useful. But if you “ride the scales” everyday when trying to pull off pounds, one may start to wonder, What about pounds in/pounds out? So, on a pound for pound basis, when food and liquid is consumed, and equal amount must be released for weight to remain constant. Basically, my question amounts to, in the metabolism of triaglycerides and glucogen, is there a proportion of liquid byproduct (water) to solid waste that must be expelled by the body? My question ignores the effects of sweat, as I think that must be dehydration weight loss. But please correct me if I’m wrong. Thanks for reading this!
This article published in April 16th 2009 speaks for itself