Q-113. At the physiological pH the DNA molecules are:
a) Positively charged
b) Negatively charged
c) Neutral
d) Amphipathic
Answer: Negatively charged
Explanation:
For all forms of DNA the global structure has an overall negative charge and the overall electrostatic potential is negative.
This is largely due to the phosphate groups of DNA which bear an overall negative charge due to the negatively charged oxygen atoms they have.
However, DNA has both positive and negative charges covering its outer structure. The charge dispersion over the global structure of DNA varies between A-DNA, B-DNA, and Z-DNA.
B-DNA has mostly negative electrostatic potential spread throughout its global exterior and concentrated mostly in major and minor grooves.