Alternate Metabolic Paths in Respiration

VBS Home page,VBS Course Navigator, Cellular Respiration, Alternate Metabolic Pathways, Previous Page, Next Page , Top of page

Of course, we don't just eat glucose. The other foods we eat are broken down by digestion and in the cell into smaller subunits which can feed into cellular respiration. The diagram below shows the fate of some of the major organic compounds metabolized by the body.

The key thing to note here is that the breakdown products are fed into cellular respiration at different points in the process. Thus, in the case of amino acids, the amino group is separated in the cell as waste material and is used to make urea which is excreted in urine. The remaining carbon skeletons from the amino acids are broken down further and fed into respiration as indicated by the arrow.

Fatty acids are broken down into smaller two carbon units join CoA to form acetyl CoA which can feed directly into the Kreb's cycle. This is one of the reasons why fats have the most energy per unit weight.

pgd revised 02/20/00

VBS Home page,VBS Course Navigator, Cellular Respiration, Alternate Metabolic Pathways, Previous Page, Next Page , Top of page