Answer :
To form a strand of DNA, the nucleotides are liked into chains with the theposphate and suger groups alternating. so the four types of nitrogenbases foind in the nucleotides are :
adenine (A)
thymine (T)
guanine (G)
cytosine (C)
adenine (A)
thymine (T)
guanine (G)
cytosine (C)