Which of the following statement is incorrect? 

The neuclosides obtained from DNA all contain 2-deoxy-d-ribose as their sugar component  

Adenine,guanine, cytosine and thyamine are the four heterocyclic base of DNA neucleosides.

The heterocyclic base of a nucleotide is attached through an N-glycoside linkage to Cl of the ribose or deoxyribose unit, and the lingkage is always the α - linkage

The central portion of nucleotide is a five monosaccharides known as furanosides