There is a question in my textbook which asks: "What does the glucose produced from photosynthesis form?" However one of the answers said that glucose forms protein. But I'm quite sure that amino acids form protein, don't they? I would be grateful if anyone out there could help me out.

  • $\begingroup$ What research have you done before asking it here? Hint: glucose is an energy source. $\endgroup$ – another 'Homo sapien' Mar 10 '17 at 9:24
  • $\begingroup$ I only know that excess protein can be converted into glucose in our body for energy, but i dont know how glucose can be converted into protein :( $\endgroup$ – david Mar 10 '17 at 9:29
  • $\begingroup$ Who asked converting glucose into protein? Also, it is possible to convert gluocse to amino acids. $\endgroup$ – another 'Homo sapien' Mar 10 '17 at 9:50
  • $\begingroup$ Can you be more specific about "one of the answer" ? Was this a multiple-choice thing ? What was the exact sentence involved ? $\endgroup$ – Oosaka Mar 10 '17 at 10:07

Photosynthesis results into formation of a carbon skeleton (a 3C or 6C skeleton). These newly formed carbon skeleton can be used to form a large number of bio-molecules which are required by a cell. For example the glucose can enter into aerobic respiration and the intermediates thus formed are used for synthesis of several molecules. Amphibolic nature of TCA

As you can specifically see from the above figure, alpha ketoglutarate is converted into glutamate which is then used for synthesis of proteins.

Alpha ketoglutarate is a keto acid can easily be aminated to give rise to amino acid.

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  • $\begingroup$ Good answer. The often taught idea that photosynthesis produces glucose is an oversimplification. It would be better to think of it as a process of carbon fixation. The resulting organic molecules can be used to synthesize the precursors of macromolecules (nucleic acids, fatty acids, amino acids and carbohydrates). $\endgroup$ – canadianer Mar 10 '17 at 20:32
  • $\begingroup$ In addition, it is not necessary that glucose will be synthesized and then it will be used for respiration. The triose (3C carbohydrate) can directly enter into glycolytic pathway. $\endgroup$ – Tushar Mar 11 '17 at 12:49

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