NEET BIOLOGY

Detailed explanation-1: -They showed that alternating deoxyribose and phosphate molecules form the twisted uprights of the DNA ladder. The rungs of the ladder are formed by complementary pairs of nitrogen bases-A always paired with T and G always paired with C.

Detailed explanation-2: -The double helix looks like a twisted ladder-the rungs of the ladder are composed of pairs of nitrogenous bases (base pairs), and the sides of the ladder are made up of alternating sugar molecules and phosphate groups.

Detailed explanation-3: -The inside of the molecule, the “steps” of the staircase, are made of the nucleotide bases Cytosine, Guanine, Adenine, and Thymine. C bonds to G by three hydrogen bonds. A bonds to T by two hydrogen bonds. A and G are double ringed structures called “purines".

Detailed explanation-4: -The rails of the DNA strand are made up of deoxyribose (a sugar) and phosphoric acid. These two molecules alternate one after the other the entire length of the rail. The rungs of the DNA strand are made up of organic bases. These organic bases attach to the deoxyribose on the ladder rails.