Chemistry of the phosphodiester bond in RNA I have been learning about the chemical structure of RNA, but I can't understand why all hydrogen atoms disappear in the phosophodiester bond between the riboses of RNA. Phosphoric acid is $H_3PO_4$: ![Phosphoric acid]( However, when it's connected to ribose the hydrogens disappear: ![Phoshphodiester bond]( Where did the hydrogens go and why?

Generally hydrogen is not shown in DNA structure. I have made a simple diagram to show where all hydrogens go:

![DNA](

There are 3 hydrogens in phosphoric acid, each of them leaves as:

* 1 H joins with 3' -OH of previous nucleotide to form H2O during DNA replication.

* 1 OH joins with H of next nucleotide to form H2O during DNA replication.

* 1 H is released as H+ (remember it was phosphoric _acid_ ), hence giving rise to the acidic character of DNA (remember it is DeoxyriboNucleic _Acid_ ).




I think you should first study DNA replication (if you haven't, yet) to get more thorough knowledge about the topic.