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One of the large macromolecules generally found in all cells, including viruses, is nucleic acids. Its function is the storage of genetic information and its expression. Nucleotides are the nucleic acid monomers which combine to make nucleic acid. There are mainly two types of nucleic acids. The nucleic acid examples are as follows:
- DNA
- RNA
DNA stands for deoxyribonucleic acid, which encodes the genes of individuals. RNA stands for ribonucleic acid, which helps in protein synthesis and other cellular roles.
Types of Nucleic Acids
DNA and RNA are two forms of nucleic acids that can be used as genetic material in some species.
Deoxyribonucleic acid (DNA)
DNA is found in all living organisms, i.e. prokaryotic and eukaryotes. It is the storehouse of genetic information of all organisms. It is the only means of transfer of traits from parents to offspring. Its structure was first demonstrated by scientists, namely James Watson and Francis Crick.
Watson and Crick gave the DNA double helix model in 1953. This is why it is called the Watson and Crick double-helical DNA model.
The separation of both strands forms DNA. Each of these strands functions as a blueprint for creating new DNA molecules.
Watson and Crick’s double-helical model of DNA
According to this model, DNA is a polymer of nucleotides. The compound is to be formulated with the presence of a pentose sugar, along with a nitrogenous base, and binding through a phosphate group. A covalent connection between the phosphate group and the sugar connects these nucleotides. In the case of DNA, the sugar is deoxyribose sugar.
The nitrogenous bases involved in this are purines including guanine and adenine, and pyrimidines, including thymine and cytosine. Both the strands of the DNA run antiparallel to each other.
The nitrogenous bases of the complementary strands make hydrogen bonds with each other giving a ladder-like appearance to the DNA. Here, purine makes a bond with the pyrimidine of the opposite strand. The bonding will be as follows:
- There is a double bond between adenine and thymine.
- There is a triple bond between guanine and cytosine.
The configuration of the DNA is stable. This property allows it to make a template for the synthesis of new DNA by the process of DNA replication and also for transcription or RNA formation.
Ribonucleic acid (RNA)
RNA is a single strand as compared to DNA. Friedrich Meischer discovered it in 1869. Just like DNA, it also has a sugar-phosphate backbone. It is also a polymer of nucleotides, including a pentose sugar called ribose sugar, a base and phosphate group. Covalent bonding holds the nucleotides together.
The purine bases adenine, guanine, and the pyrimidine bases cytosine, and uracil are nitrogenous bases present in the RNA. Uracil is present where thymine should be in the case of DNA. The hydrogen bonding will be as follows:
- The double bond between adenine and uracil.
- The triple bond between guanine and cytosine.
Generally, there are three types of RNA, namely:
- mRNA: it is very crucial for protein synthesis as it carries all the information or message required for translation.
- rRNA: it is called ribosomal RNA and is an integral part of the ribosome.
- tRNA: it is referred to as transfer RNA. It is responsible for the transfer of amino acids during translation.
RNA is made by the process of transcription, in which it is formed with the help of strands of DNA.
Functions of Nucleic Acids
The location of the DNA molecule is found to be given in the nucleus of the cell as chromosomes and also in mitochondria and chloroplast. It serves as genetic material in maximum organisms, including bacteria and DNA viruses.
Some prokaryotes and a few eukaryotes have extrachromosomal DNA plasmids and help in genetic engineering. These plasmids are crucial in DNA recombinant technology.
On the other hand, RNA is mainly involved in protein synthesis or translation. It also helps regulate the activity of genes during their development and plays a main role in cellular differentiation.
RNA can also be present as genetic material in some RNA viruses like SARS, Ebola, retrovirus, etc.
The main function is translation, which converts the information stored in DNA into protein.
Conclusion
As a result, DNA and RNA, which are nucleotide polymers with a sugar-phosphate backbone, can be considered nucleic acid examples. A pentose sugar with five carbon molecules, a nitrogenous base, and a phosphate group are the three components of nucleotides. In the case of DNA, the pentose sugar present in the molecule is deoxyribose sugar, while in the case of RNA, the sugar is ribose sugar. The purine molecules Adenine, guanine, and the pyrimidine molecules cytosine, and thymine are the bases in DNA, while purine molecules adenine, guanine, and pyrimidine molecules cytosine, and uracil are the bases in RNA.
DNA replication is the process of synthesis of new molecules of nucleic acid DNA, while transcription is the process of creating new RNA. The primary purpose of DNA is to store and transmit genetic information, while the primary function of RNA is protein translation.
