BIOMOLECULES AND ENZYMES

Detailed explanation-1: -In the Watson–Crick model, the DNA double helices are formed from the coiling of two strands of purine and pyrimidine bases. Guanine pairs with cytosine, and adenine pairs with thymine in DNA. Interstrand hydrogen bonds are responsible for this pairing.

Detailed explanation-2: -The Adenine-Thymine base pair is held together by 2 hydrogen bonds while the Guanine-Cytosine base pair is held together by 3 hydrogen bonds.

Detailed explanation-3: -A always pairs with T and G always pairs with C because these are the only combinations that allow for hydrogen bonding to occur, given the spatial constraints of the double helix, which requires there to be one purine and one pyrimidine in each base pair.

Detailed explanation-4: -Each nucleotide base can hydrogen-bond with a specific partner base in a process known as complementary base pairing: Cytosine forms three hydrogen bonds with guanine, and adenine forms two hydrogen bonds with thymine. These hydrogen-bonded nitrogenous bases are often referred to as base pairs.

Detailed explanation-5: -It is a truth universally acknowledged that a guanine–cytosine (GC) base pair has three hydrogen bonds whereas adenine–thymine (AT) has two.