<P> The two DNA strands are also known as polynucleotides since they are composed of simpler monomeric units called nucleotides . Each nucleotide is composed of one of four nitrogen - containing nucleobases ( cytosine ( C ) , guanine ( G ) , adenine ( A ) or thymine ( T ) ) , a sugar called deoxyribose , and a phosphate group . The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next , resulting in an alternating sugar - phosphate backbone . The nitrogenous bases of the two separate polynucleotide strands are bound together , according to base pairing rules ( A with T and C with G ) , with hydrogen bonds to make double - stranded DNA . </P>
<P> The two DNA strands are also known as polynucleotides since they are composed of simpler monomeric units called nucleotides . Each nucleotide is composed of one of four nitrogen - containing nucleobases ( cytosine ( C ) , guanine ( G ) , adenine ( A ) or thymine ( T ) ) , a sugar called deoxyribose , and a phosphate group . The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next , resulting in an alternating sugar - phosphate backbone . The nitrogenous bases of the two separate polynucleotide strands are bound together , according to base pairing rules ( A with T and C with G ) , with hydrogen bonds to make double - stranded DNA . </P>
what are the four elements present in dna
what are the four elements present in dna
cytosine ( C ) guanine ( G ) adenine ( A ) thymine ( T )
cytosine ( C ) guanine ( G ) adenine ( A ) thymine ( T )