In the first step of glycolysis, the glucose ring is phosphorylated. Phosphorylation is the process of adding a phosphate group to a molecule derived from ATP. As a result, at this point in glycolysis, 1 molecule of ATP has been consumed.

Is it the phosphate group, or the molecule, that is derived from ATP ?


  • $\begingroup$ Welcome to Biology! What is the molecule in your concluding question Is it the phosphate group, or the molecule, that is derived from ATP ?? $\endgroup$
    – AliceD
    May 28 '15 at 11:22
  • 2
    $\begingroup$ This is an issue of grammar; clauses should be used properly :P The sentence should be "Phosphorylation is the process of adding a phosphate group derived from ATP, to a molecule." $\endgroup$
    May 28 '15 at 12:29
  • $\begingroup$ @WYSIWYG - absolutely positively agreed - it wasn't critique, just a request to clarify the question. The answer below is great and I retracted my close vote. $\endgroup$
    – AliceD
    May 28 '15 at 13:15
  • $\begingroup$ See this post too an addition to Koustav's answer, which pretty much summarizes the phenomenon. $\endgroup$
    May 29 '15 at 5:42

The question is a bit unclear, it should be reframed as suggested by AliceD. To simply answer the question,

Glucose is the substrate, and in the first step it is converted to Glucose-6-phosphate.

Only the Phosphate group is added which originates from ATP, your notes also are a bit misleading because it tends to suggest that Hydrogen is released, which is not the case, the phostphate group in ATP loses an OH and Glucose loses an H in an SN2 reaction giving rise to Water in the process.

Always remember that ATP is categorized as an energy donor which drives chemical reactions in your body by breaking chemical bonds. ATP or Adenosine Triphosphate has three phosphate groups. The last Phosphate in ATP produces the highest amount of energy in any given chemical reaction where ATP is involved.

This is an ATP molecule.

Adenosine Triphosphate

The first P that you see is the Phosphate which gets released, and the ring that you see is a five member ring called a ribose sugar, while glucose is a six member ring.


"Is it the phosphate group, or the molecule, that is derived from ATP ?"

The Phosphate group is derived from the ATP molecule (thus why Adenosine triphosphate) NOT from the molecule it would be attaching the phosphate group to.

Phosphorylation - The process of taking this phosphate group and adding it to another molecule in the energy chain.

I hope this clears things up.


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