Cyclic ribose nucleotide phosphates, such as cyclic AMP (cAMP), are important signaling agents in living cells; all have the general structure shown here. What kind of linkage holds the phosphate to the ribose (see arrows; ribose is highlighted in blue)?

Question

Cyclic ribose nucleotide phosphates, such as cyclic AMP (cAMP), are important signaling agents in living cells; all have the general structure shown here. What kind of linkage holds the phosphate to the ribose (see arrows; ribose is highlighted in blue)?

Cyclic ribose phosphate structure with arrows indicating phosphate linkage to ribose, highlighted in blue.

Accepted Answer

All right. Hi, everyone. So this question says that cyclic nucleotides such as cyclic adenosine monophosphate are single phosphate nucleotides where sugar is bonded to a phosphate group in a cyclic arrangement. What kind of linkage holds the phosphate to the adenosine? Option A says phosphate and hydride linkage. Option B says phosphate ester linkage option C says mixed and hydride linkage and option D says A and B now first lets clarify what the types of linkages are starting off with a phosphate Esther linkage. Now recall that a phosphate ester linkage is a connection between an R group or an ocular carbon and a phosphate group, right? So we take an ocho carbon for example, ch three and we connect that to one of the oxygens, excuse me of our phosphate group. So this would be one example. Now, by contrast, we also have a phosphate and hydride linkage in which instead of having one phosphate group connect to one all kill group, then two phosphate groups are connecting together. And so in this case, we're going to end up with one oxygen atom in between two atoms of phosphorus in the phosphate and hydride linkage, I realized I almost drew a hydroxy group on oxygen. So let me just fix that there, right. So here, like I mentioned previously, we have an oxygen atom in between two phosphate groups or two phosphate or phosphorus atoms. So last but not least is the mixed anhydride linkage. Now, like the name implies, this is essentially a mix of the phosphate ester linkage and the phosphate anhydride linkage. But in this case, I find it easier to remember by comparing its structure to that of the phosphate and hydride linkage, right, because we we are still going to have an oxygen atom in the center of the structure. But in this case, the oxygen atom in the center is connected to one phosphorus atom on one side and one carbon atom on the other side. But the difference is that even though the phosphorus atom does come from a phosphate group, the carbon it is attached to contain the car bottle which would make it part of an AO group. So here you can see better that the both anhydride linkages look very similar. But the mixed anhydride linkage has oxygen connected to one phosphorus atom. Whereas in the phosphate, an hydride linkage, it is connected to two. So now I can go ahead and scroll up here to consider the structure of cyclic adenosine monophosphate. Specifically the linkages between adenosine here which is the sugar backbone and our phosphate group. So in this case, right, I want to draw your attention to the oxygen atoms on either side of our phosphorus atom. Because my next step is to go ahead and see what is connected to that oxygen opposite the phosphorus atom of the phosphate group. And what I'll notice here is that both of them are connected to carbons, but that carbon is not a car bottle, neither of them aren't. Therefore, they are both ocho carbs, which means that we have an atom of oxygen connected to an acho carbon and a phosphate group. Therefore, both linkages are phosphate ester linkages, which means that our answer is going to be option B in the multiple choice and there you have it. So with that being said, thank you so very much for watching and I hope you found this helpful.

Cyclic ribose nucleotide phosphates, such as cyclic AMP (cAMP), are important signaling agents in living cells; all have the general structure shown here. What kind of linkage holds the phosphate to the ribose (see arrows; ribose is highlighted in blue)?

Verified video answer for a similar problem:

Key Concepts

Cyclic Nucleotide Structure

Phosphate-Ribose Linkage

Signaling Role of cAMP