The base sequence in one of the strands of DNA is TAGCATGAT
(i) Give the base sequence of its complementary strand.
(ii) How are these base pairs held together in a DNA molecule?
(iii) Explain the base complementarity rules. Name the scientist who framed this rule .
(i) The base sequence of its complementary strand is : ATCGTACTA
(ii) The base pairs are held together in a DNA molecule by hydrogen bonds. Each base pair consists of one 2-ringed purine and one 1-ringed pyrimidine. Therefore all the base pairs have equal width and DNA helix has a constant diameter.
(iii) The base pairs are said to be complementary to each other and thus, if the sequence of bases in one strand is known then the sequence of other strand can be predicted. According to the rule in DNA the ratio between Adenine and Thymine and Guanine and Cytosine are constant and equals one.
The rule was framed by Erwin Chargaff.