So this is the open chain form of our ribose molecules. So we have carbon number 1234 and five. And notice, just like the glucose, ribose is an aldose, it contains an aldehyde. And so what happens is we have that same type of intramolecular nucleophilic. Additional reaction take place and this attacks this electrophile nucleophilically, forming a purple bond that is shown here. Now, this is an example of the beta Dribribribe.