NEET BIOLOGY

Detailed explanation-1: -A phosphate backbone is the portion of the DNA double helix that provides structural support to the molecule. 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.

Detailed explanation-2: -The backbone of a DNA molecule consists of the phosphate groups and the deoxyribose sugars, whereas the base region of the DNA molecule consists of the nitrogenous bases; therefore, the backbone of DNA is made up of phosphate groups and pentose sugars.

Detailed explanation-3: -A sugar-phosphate backbone (alternating grey-dark grey) joins together nucleotides in a DNA sequence. The sugar-phosphate backbone forms the structural framework of nucleic acids, including DNA and RNA. This backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

Detailed explanation-4: -DNA consists of a pair of chains of a sugar-phosphate backbone linked by pyrimidine and purine bases to form adouble helix (Fig. 96.1). The sugar in DNA is deoxyribose. The pyrimidines are cytosine (C) and thymine (T); the purines are guanine (G) and adenine (A).

Detailed explanation-5: -The sugars and phosphates are referred to as the “backbone” because they provide the structure and support of the molecule, keeping these bases in the correct order. How can an enormous amount of DNA fit inside one cell? The chromosomes that are found in prokaryotes are different from those found in eukaryotes.