Introduction
Biological sciences that study the principles of storage, realization, and transmission of genetic information, and the structure and functions of irregular biopolymers belong to molecular biology. Biopolymers, high-molecular organic compounds that were formed from nucleotide residues, are nucleic acids. There are two types of nucleic acids in nature: DNA and RNA.
They are involved in protein biosynthesis and store information about a living organism, determining its development, growth, and heredity.
Discussion
DNA is a nucleic acid that contains the genotype of an individual and transmits information, reproducing itself. It is a biopolymer whose monomer is a nucleotide. Each nucleotide consists of a phosphoric acid residue attached to the sugar deoxyribose. It is the presence of characteristic sugar that makes up one of the main differences between DNA and RNA. In DNA, nucleotides are connected covalently to each other in long polynucleotide chains (Krogh et al., 2018). These chains are paired together using hydrogen bonds into a secondary structure called a double helix. The backbone of each of the chains consists of alternating phosphates and sugars.
In the vast majority of living organisms, DNA consists of not one, but two polynucleotide chains. These two long chains are twisted one around the other in the form of a double helix. The backbone of each of the chains consists of alternating phosphates and sugars. Within one DNA chain, neighboring nucleotides are connected by phosphodiester bonds, which are formed as a result of the interaction between the 3′-hydroxyl (3’—OH) group of the deoxyribose molecule of one nucleotide and the 5′-phosphate group (5’—PO3) of the other (De Chadarevian, 2020). The asymmetric ends of the DNA chain are called 3′ (three prime) and 5′ (five prime) (De Chadarevian, 2020). The polarity of the chain plays an important role in DNA synthesis.
Each base on one of the chains binds to one specific base on the second chain. Such a specific binding is called complementary. The complementarity of a double helix means that the information contained in one chain is contained in another chain. Purines are complementary to pyrimidines: adenine forms bonds only with thymine, and cytosine — with guanine (De Chadarevian, 2020). In the double helix, the chains are also linked by hydrophobic interactions and stacking, which do not depend on the DNA base sequence.
DNA is a carrier of genetic information recorded as a sequence of nucleotides using a genetic code. DNA molecules are associated with two fundamental properties of living organisms — heredity and variability. During the process called DNA replication, two copies of the original chain are formed, and the resulting cells are genetically identical to the original. Genetic information is transmitted in the processes of transcription (synthesis of RNA molecules on the DNA matrix) and translation (synthesis of proteins on the RNA matrix).
The sequence of nucleotides “encodes” information about various types of RNA: informational, or matrix (mRNA), ribosomal (rRNA), and transport (tRNA). All these types of RNA are synthesized based on DNA in the process of transcription. Their role in protein biosynthesis is different. Informational RNA contains information about the sequence of amino acids in a protein, ribosomal RNAs serve as the basis for ribosomes, and transport RNAs deliver amino acids to the protein assembly site (Rauf, 2018). In its structure, RNA resembles deoxyribonucleic acid and also consists of four types of polymer nucleotides. Three of them are similar to DNA, but instead of thymine, RNA contains uracil.
Conclusion
When DNA was discovered, its role was not so obvious. Even today, even though much more information has been disclosed, some questions remain unanswered. While some, perhaps, have not even been formulated yet. The well-known biological significance of DNA and RNA lies in the fact that DNA transmits hereditary information, and RNA participates in protein synthesis and encodes the protein structure.
References
De Chadarevian, S. (2020). Heredity under the microscope. University of Chicago Press.
Krogh, T. J., Møller-Jensen, J., & Kaleta, C. (2018). Impact of chromosomal architecture on the function and evolution of bacterial genomes. Frontiers in microbiology, 9, 2019.
Rauf, D. (2018). DNA, RNA, and the Inheritance of Traits. Enslow Publishing, LLC. Web.