How Are the Structures of RNA and DNA Similar, and How Do They Differ?
DNA and RNA play an important role in the DNA replication process and subsequently in the cell division process. How are the structures of RNA and DNA similar and how do they differ? Both DNA and RNA are nucleic acids that occupy the cells. They share many similarities, especially in terms of structure, but they also have many differences. Here we will explore how both ribonucleic acids are similar and how they differ.
DNA and RNA Similarities
How are the structures of RNA and DNA similar? There are some features that RNA and DNA share.
They are both nucleic acids consisting of fairly similar components.
As mentioned above, both RNA and DNA are nucleic acids, with RNA being a ribonucleic acid and DNA deoxyribose nucleic acid. Nucleic acid is a small biomolecule called biopolymer that consists of nucleotides. Nucleotides are the monomers that consist of a 5-carbon sugar, a phosphate group and a nitrogenous base. Both DNA and RNA structurally consist of these monomers.
Both DNA and RNA have four nitrogenous bases.
Both DNA and RNA have four nitrogenous bases. These nitrogenous bases bind with each other in a fairly similar pattern. The binding of these bases appear superficially the same on both DNA and RNA.
They both appear as double-helices.
How are the structures of RNA and DNA similar? Another structural similarity between RNA and DNA is that they both appear as double-helices. Although there is a significant difference that we will discuss more later, superficially, they look as double-helices with bases binding the strand.
Both DNA and RNA has a phosphate backbone.
One of the most important components of both DNA and RNA is their phosphate backbone. The nitrogenous bases of both are attached to this backbone. This phosphate backbone is negatively charged—a characteristic that allows both DNA and RNA to carry out many of their genetic functions.
They work together in the nucleus.
DNA and RNA work together in the nucleus to satisfy their primary functions: protein synthesis and gene expressions.
So, how are the structures of DNA and RNA similar? In terms of structure, both DNA and RNA, at least superficially, are the same. They are both nucleic acids that consist of monomers, which subsequently consist of pentose (5-carbon) sugar, a phosphate backbone, and nitrogenous bases. They also appear as double-helices with few but significant differences. In terms of function, both DNA and RNA work hand in hand in the synthesis of protein and in the determination of gene expressions.
However, as I have emphasized above, the similarities between DNA and RNA are mostly superficial. Deep inside, DNA and RNA have some differences that determine not only their own specific structures, but also functions.
DNA and RNA Differences
There are some specific features that make DNA and RNA different.
They have different type pentose sugar.
One factor that determines why one of the nucleic acids is called DNA and the other is called RNA is their respective pentose sugar. In the case of DNA, the sugar is called deoxyribose whereas in RNA, it is called ribose, hence the name deoxyribose nucleic acid and ribose nucleic acid respectively for DNA and RNA. The deoxy prefix in the DNA name means that the sugar compound of the DNA contains less oxygen. In other words, the sugar compound of RNA contains -OH group in place of DNA’s -H.
They share three similar nitrogenous bases with one different for each.
Both DNA and RNA have four nitrogenous or nucleotide bases, three of which, i.e. Adenine (A), Guanine (G), and Cytosine (C), are shared by both DNA and RNA. They, however, have different fourth nucleotide. In DNA, the fourth nucleotide is called Thymine (T) whereas in RNA, it is called Uracil. The binding pattern of these nucleotides is thus adjusted accordingly. In both DNA and RNA, Guanine binds with Cytosine; however, the pair for Adenine is different in DNA and RNA. In the former, Adenine binds with Thymine whereas in the latter, it binds with Uracil.
Thymine and uracil share very much similar form and function. The only difference is that uracil doesn’t have a methyl group whereas thymine has. The methylation of uracil thus produce thymine.
This small difference, however, carries a significant effect. Uracil is easier to make and therefore a perfect choice for RNA that is not designed for longevity whereas thymine is more difficult to produce and therefore a good choice for ensuring the integrity of DNA.
Both appear as double-helices, but DNA consists of two strands whereas RNA only one.
Both DNA and RNA appear as double-helices; however, the double-helix formation of DNA consists of two parallel strands bound by nucleotides. RNA also appears as double-helix; however, the double-helix formation of RNA is created by one single strand folded onto itself. RNA also doesn’t always look as a double-helix. It forms a double-helix formation only intermittently.
DNA is much longer than RNA.
While DNA is a long polymer, RNA is much shorter and its molecules are variable in length. Even the longest RNA molecule is still much shorter than the DNA polymer.
DNA and RNA have different level of ultraviolet resistance.
DNA is more fragile when exposed to ultraviolet radiation. DNA is more easily damaged by ultraviolet light whereas RNA is more resistant to damage when exposed to ultraviolet light.
DNA is more stable than RNA.
DNA is less chemically reactive than RNA. This is because DNA has deoxyribose sugar that contains less oxygen. RNA, on the other hand is more reactive due to its ribose sugar and thus more susceptible to enzyme attack.
DNA is located in the nucleus forever.
DNA stays in the nucleus forever whereas RNA can exits and enters the nucleus whenever needed. DNA outside the nucleus, i.e. the one in mitochondria and plastids, does exist, but it also never exits its respective host.
So, how are the structures of DNA and RNA similar? DNA and RNA shares many similar features; however, those features are mostly superficial. Deep inside, DNA and RNA are two distinct nucleic acids that have different structure and function.