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Deoxyribonucleic acid, commonly known as DNA, is a fundamental molecule that carries the genetic blueprint of all living organisms. It is essential for life as it contains the instructions needed for the organism to develop, function, reproduce, and transmit traits to the next generation.

DNA is structured in the form of a double helix, a winding, ladder-shaped molecule that consists of two long strands that spiral around a common axis. These strands are composed of repeating units called nucleotides, each made up of a sugar molecule, a phosphate group, and a nitrogenous base. The sequence of these nitrogenous bases along the DNA strand holds the key to genetic information.

In terms of their chemical differences, the sugar present in DNA is called deoxyribose because it is a version of ribose sugar from which one oxygen atom has been removed. This structural distinction is critical when comparing the DNA molecule with RNA (ribonucleic acid), which contains ribose sugar.

Nucleotide bases are the components of DNA that store genetic information. They are often referred to as the 'letters' of the genetic code. There are four main types of nucleotide bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases form base pairs, which are the 'rungs' of the DNA ladder, with adenine pairing with thymine, and cytosine pairing with guanine.

Each base is attached to a sugar molecule and a phosphate group, forming a nucleotide. These nucleotides link together to form long chains, with the phosphate of one nucleotide connecting to the sugar of the next. The order of these bases along the DNA strand is what determines the genetic information that the DNA molecule carries, as it dictates the sequence of amino acids that will be assembled into proteins during the process of gene expression.

The phosphate backbone is one of the key structural elements of the DNA molecule. It forms the framework that holds the nucleotide bases in place and contributes to the overall stability of the DNA double helix. The backbone is made up of alternating sugar and phosphate groups, with the deoxyribose sugar connected to two phosphate groups - one at the 5' carbon atom and one at the 3' carbon atom.

This alternating sugar-phosphate structure results in a molecule with a 'direction', often denoted as 5' to 3'. The phosphodiester bonds that link adjacent sugar and phosphate groups give the DNA its structural integrity. When referring to the antiparallel strands of DNA, one strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction, ensuring proper base pairing and helical structure. It is also the phosphate backbone that provides the negative charge to the DNA molecule due to the presence of phosphate groups, which is paramount for interactions with proteins and other molecules inside the cell.