Studying Life, Chemistry

Nucleic acids are responsible for the storage, expression, and transmission of genetic information. The two classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA molecules store genetic information coded in the sequence of their building blocks. RNA molecules are involved in decoding this information into instructions for linking a specific sequence of amino acids to form a polypeptide.

Monomer, known as a nucleotide, has three components:
- a phosphate group,
- a pentose sugar,
- a single or a double ring of carbon and nitrogen atoms known as a base.

A nucleotide of DNA is called a deoxyribonucleotide (five-carbon sugar – deoxyribose), one of RNA is a ribonucleotide.
Four different nucleotides are present in DNA, corresponding to the four different bases that can be linked to deoxyribose. The purine bases, adenine (A) and guanine (G), have a fused double ring of carbon and nitrogen atoms, and the pyrimidine bases, cytosine (C) and thymine (T), have a single-ring structure.
Two hydrogen bonds form between adenine and thymine, whereas three hydrogen bonds are formed between guanine and cytosine.
Also, the pyrimidine base thymine found in DNA is replaces in RNA with the pyrimidine base uracil (U).

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