Now before we go on to nucleotides, let's mention one more thing about nucleotides. So notice that the bond in a nucleotide that connects these two different molecules is always between carbon number one, one prime on the sugar and on nitrogen found on the base. Now if the base is a purine and that means we have these two fuse rings, then this nitrogen number one will always be bound to carbon number one. If this base was a puridine when we have only a single ring, then a nitrogen would be nitrogen number one. So the bond always takes place between carbon number one and a nitrogen atom found on our base. Now let's move on to nucleotide.