Saturday, March 10, 2012

What is the structure of Pentose sugar in DNA and how does it attach with adenine and guanine? Thnx in advance?

I just want to know the way in which Adenine and Guanine attach themselves to the Pentose sugar in the DNA.What is the structure of Pentose sugar in DNA and how does it attach with adenine and guanine? Thnx in advance?
Pentose is a 5-carbon sugar. Consider a pentagon whose apex is oxygen atom. From this O- atom in a clockwise direction there are 4 carbon atoms, namely, 1', 2', 3' and 4' at each of four other vertices. The 5th carbon atom is attached to 4' - carbon as -CH2OH group. The other valency of this 4' - carbon is satisfied with one -H atom. The rest of the three carbon atoms should contain one -H atom and one -OH group, except the 2' - caron, whose -OH group is dehydrogenated to -H group. That is why DNA is deoxyribose.

In DNA molecule phosphate groups are attached in between two ribose monomers. Thus, each ribose molecule is attached to two phosphate groups- one at 3' carbon, another at 5' carbon. Two strands of DNA are complimentary and if one starts like 3' - 5' -3' ----------3' - 5', then another will be 5' - 3' - 5' ------ 5' - 3'. During replication one strand moves along 5' - 3' and the other along 3' to 5'. The steps of DNA double-helix ladder are made of bases. One base attaches to each ribose unit on both linear sugar-phosphate chains of two strands at the 2' - carbon atom and the complimentary base (A-T and G-C)of other strand attaches to the former through hydrogen bonding.What is the structure of Pentose sugar in DNA and how does it attach with adenine and guanine? Thnx in advance?
Purines bond to the C1' of the sugar at their N9 atoms - Guanine and Adenine.



Pyrimidines bond to the sugar C1' atom at their N1 atoms -

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