Nucleic Acids and Nucleotides

Nucleic acids are polymers of nucleotides– molecules composed of a pentose sugar, a nitrogen-containing base, and a phosphate group.

There are two types of nucleic acids: deoxyribonucleic acid, DNA, and ribonucleic acid, RNA.

Their chemical structures differ depending on which pentose sugar and nitrogenous bases they contain.

The pentose sugar in RNA is ribose, which has a hydroxyl group attached to carbon-2. The sugar in DNA is deoxyribose, which has only a hydrogen atom but no oxygen at carbon-2.

The nitrogenous base is bonded to carbon-1 and the phosphate at carbon-5. Both RNA and DNA contain the bases adenine, cytosine, and guanine, but DNA has thymine, while RNA has uracil.

In DNA and RNA, guanine and cytosine form complementary base pairs linked by three hydrogen bonds. Adenine and thymine form base pairs in DNA, while adenine and uracil pair in RNA, both linked together by two hydrogen bonds.