Base Stacking of DNA is characterised by
**Core Concept**
Base stacking of DNA refers to the arrangement of nitrogenous bases in a stacked configuration, where the planar rings of the bases are perpendicular to the DNA axis. This type of interaction is crucial for the stabilization of the DNA double helix structure.
**Why the Correct Answer is Right**
Base stacking is facilitated by the planarity of the nitrogenous bases, specifically adenine (A) and guanine (G), which have a large number of electrons delocalized in their aromatic rings. This allows for pi-pi stacking interactions, where the electrons in the aromatic rings of adjacent bases interact, leading to a stabilizing effect on the DNA double helix. The correct answer is related to the type of interaction that occurs between the nitrogenous bases in base stacking.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the type of interaction that occurs in base stacking.
**Option B:** This option is incorrect because it refers to a different type of interaction that occurs between the sugar-phosphate backbone and the nitrogenous bases in DNA, rather than the interaction between the nitrogenous bases themselves.
**Option C:** This option is incorrect because it is a characteristic of base pairing, not base stacking.
**Clinical Pearl / High-Yield Fact**
Base stacking is an example of a non-covalent interaction that plays a crucial role in the stability of the DNA double helix. Understanding the different types of interactions that occur in DNA is essential for grasping the fundamental principles of molecular biology.
**Correct Answer: D. Hydrophobic interactions.**