Fighting Misconceptions: RNA vs DNA
Written By: Arman Momeni
In Science ReWired’s article Fighting Misconceptions: Viruses vs Bacteria we defined the crucial differences between a virus and a bacterium. We established that while bacteria are unicellular living organisms, viruses, on the other hand, are an infectious segment of nucleic acid, which can be either DNA or RNA. DNA and RNA are slightly different from each other, but their function remains the same. As sequences of genetic code, DNA and RNA ultimately tell and organism what to do, specializing in instructions on protein and enzyme synthesis. Proteins and enzymes are another set of foundational molecular components that allow for the function of all lifeforms.
In general, RNA genomes have some slightly different characteristics than DNA genomes (which are found in humans). RNA genomes have some subtle differences within their transcription/translation cycle, mutate faster, and are able to swap parts of their genome with nearby viruses. However, there are two main differences that distinguish DNA from RNA. First, RNA contains ribose sugar, whereas DNA contains a slightly different deoxyribose sugar. Second, RNA has the nucleobase uracil while DNA contains thymine. However, to the average reader this all sounds like gibberish, so what do these terms actually mean in terms of the structure and function of the genetic codes?
Ribose vs Deoxyribose Sugar:
Deoxyribose and Ribose are both simple sugars, they are both biologically important and act as foundations in the formation of the blueprints of an organism. Ribose is a pentose sugar, which means that it has five carbon atoms. When ribose sugar is combined with a nitrogenous base it forms ribonucleoside, which then needs to attach to a phosphate group to become a ribonucleotide. Ribonucleotide is a necessary component for nucleic acids. Ribose sugar, found in RNA, helps RNA code, and decode genetic information. On the other hand, Deoxyribose is an aldopentose sugar, which still has five carbon atoms, but also contains an aldehyde group at position 1. An aldehyde group is simply a classification for when a carbon atom shares a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom/group of atoms. Deoxyribose is able to help enzymes in the body differentiate between RNA and DNA. Deoxyribose is fundamental in DNA, which is the main source of genetic information. DNA comprises of the bases: adenine, thymine, guanine, cytosine. A base is simply an outlet for DNA to store information.
Uracil vs Thymine
Above we established the bases for DNA, which were adenine, guanine, cytosine, and thymine. RNA also has four nucleobases that make up the nucleic acid. However, these bases are guanine, cytosine, adenine, and uracil, lacking thymine. The key difference between Uracil and Thymine is their occurrence, as in uracil only occurs in RNA and thymine only occurs in DNA. Thymine and Uracil also contain different molecular formulas and molar masses with Uracil being slightly lighter than Thymine.
Works Cited
BYJUS. (2022, October 21). Difference between deoxyribose and ribose - an overview. BYJUS. https://byjus.com/biology/difference-between-deoxyribose-and-ribose/#:~:text=The%20structure%20of%20Ribose%20and,more%20stable%20than%20ribose%20sugar.
Lakna. (2017, May 18). Difference between uracil and thymine: Definition, structure, characteristics. Pediaa.Com. https://pediaa.com/difference-between-uracil-and-thymine/
