1. Double Helix: There are two strands in the DNA molecule. It is called double strand or double helix. The arrangement of the two sutras is like a stairwell. Each helix is a polynucleotide.
2. Reverse Strands: The two strands of a DNA molecule lie side by side in opposite directions. One is 5-3 carbon oriented and the other is 3-5 carbon oriented. The positions of the two sutras are called antiparallel. These two formulas are positioned around an imaginary central axis.
3. Railings: Deoxyribose sugars and phosphates form the railings on both sides of the ladder. Deoxyribose sugars and phosphates are sequentially linked to form two railings.
4. Sopan: There are many steps in the middle of the stairs. These steps are called steps. Different types of nitrogenous alkalis are added to form this terrace.
5. Hydrogen Bonding: Nitrogenous bases are bonded to each other by hydrogen bonding. According to the bonding principle, Adenine and Thymine are bonded by two hydrogen bonds (A=T) and Cytosine and Guanine are bonded by three hydrogen bonds (G≡C). There are 25 hydrogen bonds per patch of DNA molecule.
6. Carbon attachment: Nitrogenous bases are always attached to the 1st carbon of the pentose sugar. A phosphate is attached to carbon 5 of one nucleotide while a phosphate is attached to carbon 3 of another nucleotide.
7. Alkalinity: DNA molecules contain equal amounts of adenine and thymine and guanine and cytosine.
8. Diameter: The diameter of the double helix of each DNA molecule is 20 Å. But this diameter may vary according to the length.
9. Patch Length: Each patch of double helix consists of 10 pairs of mononucleotides. A pair of mononucleotides is 3.4 Å in length. Thus the length of each patch is 10×3.4= 34 Å or 3.4 nm.
10. Grooves: There are two grooves in each turn of the double helix. One is the major (deep) groove 22 nm and the other is the minor (shallow) groove 12 nm.
11. Molecular Weight: Molecular weight of DNA is 106-109 daltons.