1. DNA is made up of four types of nucleotides.
2. Know the chemical structure of nucleotides.
3. Since DNA is acidic, the phosphate group will be exposed.
4. Adenine and Thymine are equal and Guanine and Cytosine are equal in Chargaff’s principle.
5. Wilkins and Franklin presented the physical structure of the DNA molecule by X-ray crystallography. Its molecular distance maps are 2 nm, 0.34 nm and 3.4 nm.
6. Two purines cannot reversibly sit within 2.0 nm of each other. The two pyrimidines sit opposite each other at a distance of less than 2.0 nm. So if the purine and pyrimidine sit opposite each other, the distance is 2.0 nm.
7. Adenine and Thymine are joined by two hydrogen bonds and Guanine and Cytosine by three hydrogen bonds.
8. The two sutrakas are different, but complementary.