LIFE SCIENCE

Detailed explanation-1: -DNA consists of two strands that wind around each other like a twisted ladder. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases–adenine (A), cytosine (C), guanine (G), or thymine (T).

Detailed explanation-2: -The sugar-phosphate backbone of DNA is a strand of repeating ribose sugar and phosphate compounds bonded together. They form the backbone because the bases that make up the genetic information of DNA are bonded to this backbone.

Detailed explanation-3: -The deoxyribonucleotides are made up of phosphoric acid and deoxyribonucleosides. The deoxyribonucleosides are made up of deoxyribose sugars and nitrogenous bases. The deoxyribonucleotides are joined to each other with the help of 3’, 5’ phosphodiester bonds forming the backbone of single DNA chain.

Detailed explanation-4: -The DNA strand’s “backbone” is constituted by pentose sugar and phosphate, while the nitrogenous bases project inside forming the bridges between the strands.

Detailed explanation-5: -The nucleotides are covalently linked together in a chain through the sugars and phosphates, which thus form a “backbone” of alternating sugar-phosphate-sugar-phosphate (see Figure 4-3).