Describe the structure of DNA .
Answer
DNA is a polymer of
nucleotides arranged in a double helix of two strands of nucleotides. Each
nucleotide consists of a pentose sugar, deoxyribose ,a phosphate group and one
of the four organic bases (adenine ,guanine ,cytosine or thymine ).The two
strands are linked to each other by hydrogen bonding between the complementary
organic bases of each strand,forming “rungs” similar to those a ladder. The
alternating molecules of deoxyribose and phosphate form the “uprights”. The two
polynucleotide strands also run antiparallel to each other,i.e. the 3’ end of
one strand is paired to its complementary base by the following arrangement :
Adenine-Thymine , Guanine –Cytosine
The DNA double helix
structure comprises many millions of nucleotides and is many thousands of
kilobases long. The distance between the two strands of polynucleotides is
approximately 2.0nm and every 10 base pairs that constitute one turn of
the double helix are approximately 3.5nm long.
Assignment submitted by C.,L.,Ooi, W.Y.,Ng, K.Q., Beh, Y.H.,Beh, Dhevan 2011/2012 (IBM)
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