- Tertiary structure of DNA is it location in three-dimensional space. There are 4 different structural variations in DNA forms:
- Right or left handed
- Length of the helix turn
- Number of base pairs per turn
- Difference in size between the major and minor grooves.
DNA's tertiary arrangement in space includes B-DNA, A-DNA and Z-DNA. The possible confirmations in which the DNA exists include A-DNA, B-DNA and Z-DNA. B-DNA and Z-DNA are the only functional forms that have been observed in organisms. The DNA adopts conformation depending upon the hydration level, DNA sequence and the amount and direction of supercoiling, chemical modification of bases, types and concentration of metal ions and also polyamines in solution.