Compared and contrast DNA and RNA

DNA is a polymer. The monomer units of DNA are nucleotides, and the polymer is know as a ''polynucleotide''. Each nucleotide consist of a 5 carbon sugar (deoxyribose) , a nitrogen containing a base attached to the sugar, and a phosphate group. There are four different types of nucleotides found in DNA, differing only in the nitrogenous base. The four nucleotides are given one letter abbreviation as shorthand for the four bases.

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  A is for Adenine
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  G is for Guanine
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  C is for Cytosine
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  T is fro Thymine

Purine Bases

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  Adenine and Guanine are purines the largest bases of DNA.

    Structure of A and G

The 9 atoms that make up the fused rings (5 Carbon, 4 nitrogen) are numbered 1-9. All rings atoms lie in the same plane.

Pyrimidine Bases

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  Cytosine and Thymine are pyrimidines. The 6 atoms, (4 carbon, 2 nitrogen) are numbered 1-6 . Like purines, all pyrimidines ring atoms lie in the same plane.

    Structure of T and C

Deoxyribose Sugar

The deoxyribose sugar of DNA backbone has 5 carbons and 3 oxygen's. The carbon atoms are numbered 1', 2', 3', 4' and 5' to distinguish from the numbering of the atoms of purine and pyrimidine rings. The hydroxyl group on the 5'- and 3'- carbons link to the phosphate group to form the DNA backbone. Deoxyribose lacks an hydroxyl group at the 2'- position when compared to ribose, the sugar component of RNA.

    Structure of Deoxyribose

Nucleotides

 A nucleotide is one of the four DNA bases covalently attach to the C'1 position of a sugar. Th sugar in deoxynucleoside is 2'-dioxyribose. The sugar in the nucleotide is ribose. Nucleotide differ from nucleotides in that they lack phosphate groups. The four different nucleotides of DNA are deoxyadenosine (dA), deoxyguanosine (dG), deoxycytosine (dC), and (deoxy) Thymidine (dT or T ).

Structure of dA

In dA and dG, there is an ''N-glycoside'' bond between the sugar C1' and N9 of the purine.

A nucleotide is a nucleotide with one or more phosphate groups covalently attach to the 3'-and/or 5' hydroxyl group(s).

RNA

Most RNA cellular molecules are single stranded.they may form secondary structures such as stem-loop and hairpin. 

Secondary structure or RNA. (a) Stem-loop (b) hairpin

The main role of RNA is to participated in protein synthesis, which requires three classes of RNA:

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

Other classes of RNA include:

Ribosomes

The RNA molecule with catalytic activity.

Small RNA molecules

RNA interference and another functions.