Sugar. Both DNA and RNA are built with a sugar backbone, but whereas the sugar in DNA is called deoxyribose (left in image), the sugar in RNA is called simply ribose (right in image).

DNA and RNA are similar in many aspects, but they also differ in key ways. One of the primary differences between DNA and RNA is that RNA has a specific sugar that DNA does not. RNA has the sugar ribose in it.

In DNA, Oxygen is absent at position C-2 of the ribose sugar. RNA has D-ribose as sugar. Glucose has six carbon atoms and ribose has five carbon atoms.

Apart from being the carrier for the four bases (adenine, guanine, cytosine, and adenine) the sugar is the anchor for the phosphate (coming from the phosphodiester bonds of the triphosphate precursors) which sits then on the outside of the completed polymer. The phosphate moiety makes the final product the DNA an acid.

The sugar-phosphate backbone has a negative charge that allows DNA to easily dissolve in water and is also used by proteins that bind the DNA. These proteins often have positive areas that bind strongly to the negative charge of the phosphate groups.

Explanation: DNA stands for “deoxyribonucleic acid.” The backbone of DNA is comprised of alternating sugar and phosphate units, in which the sugar is deoxyribose. The backbone of RNA is also comprised of sugar and phosphate units, but uses the sugar ribose.

deoxyribose

DNA is called the blueprint of life because it contains the instructions needed for an organism to grow, develop, survive and reproduce. DNA does this by controlling protein synthesis. Proteins do most of the work in cells, and are the basic unit of structure and function in the cells of organisms.

DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.

RNA growth is always in the 5′ → 3′ direction: in other words, nucleotides are always added at a 3′ growing tip, as shown in Figure 10-6b. Because of the antiparallel nature of the nucleotide pairing, the fact that RNA is synthesized 5′ → 3′ means that the template strand must be oriented 3′ → 5′.

Both the Okazaki fragments and the leading strand are synthesized in the 5′ → 3′ direction. The discontinuous assembly of the lagging strand enables 5′ → 3′ polymerization at the nucleotide level to give rise to overall growth in the 3′ → 5′ direction.

Okazaki fragments form because the lagging strand that is being formed have to be formed in segments of 100–200 nucleotides. This is done DNA polymerase making small RNA primers along the lagging strand which are produced much more slowly than the process of DNA synthesis on the leading strand.

Leading Strand and Lagging Strand The first one is called the leading strand. This is the parent strand of DNA which runs in the 3′ to 5′ direction toward the fork, and it’s able to be replicated continuously by DNA polymerase. The other strand is called the lagging strand.

The process occurs consistent with the requirement that new strand synthesis always occurs 5′ 3′. Synthesis off the leading strand (below, blue) occurs in the 5′ 3′ direction, which is oriented towards the replication fork (lower DNA molecule, red strand).