Nucleic Acid Definition

Nucleic acids are macromolecules or biopolymers that are essential to all recognised forms of life. Nucleotides, which are monomer components made up of a base that is nitrogenous, a group of phosphates, and a sugar-containing five carbons, are what make up DNA and RNA. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) make up the two main subcategories of nucleic acids.

The main molecules that carry information in organisms and the components that form blocks for genetic material are naturally occurring chemicals known as nucleic acids. All living organisms include large quantities of nucleic acids, which are responsible for creating, encoding, and storing the information that is contained in each cell that exists of every type of life on Earth.

They then serve to communicate and communicate that information within as well as outside the cell nucleus to the internal processes of the cell, and ultimately to the offspring of each living organism. The nucleic acid sequence, which gives the 'ladder-step' ordering like nucleotides inside the molecules of RNA and DNA, is where the encoded information is both contained and transmitted. In controlling protein synthesis, they are particularly significant.

The five fundamentals, or canonical, nucleobases are cytosine, adenine, guanine, thymine as and uracil. In order to generate chains of base pairs, a string of nucleotides are bonded to form helical backhauls?typically one for RNA and two for DNA. In RNA as well as DNA, respectively, the only elements present are thymine and uracil.

These nucleobase pairs' precise sequencing in DNA allows for the storage and transmission of genetic information as genes, which is accomplished through the use of amino acids and the protein synthesis process. Base-pair sequencing in RNA enables the production of new proteins that define the structural components and the majority of the chemical reactions in all living things.

In 1869, Friedrich Miescher at the University of T�bingen in Germany made the initial discovery of nucleic acid. He uttered nuclein as the word for it. Albrecht Kossel further refined the material in the first months of the 1880s and identified its extremely acidic characteristics. Later, he also determined the nucleobases. Richard Altmann coined the phrase "nucleic acid" in 1889; at the time, DNA and RNA were not distinguished from one another. The first DNA X-ray diffraction pattern was published by Astbury and Bell in 1938.

Watson and Crick suggested the double-helix structure of DNA in 1953, and the Avery-MacLeod-McCarty experiment demonstrated that DNA is the carrier of genetic information in 1944. The foundation for genomic and forensic science, as well as the biotechnology and pharmaceutical sectors, is laid by experimental studies of nucleic acids, which make up a significant portion of contemporary biological and medical research.

Naming Conventions and Occurrence

DNA and RNA are members of a family of biopolymers, and the word "nucleic acid" is used to refer to all of these biopolymers collectively. In addition to being located in the center of the cell, where they were first discovered, phosphate bonds in DNA and RNA (which are associated with phosphoric acid) are what gave rise to the term "nucleic acids." Since then, it has been demonstrated that nucleic acids have been identified in all known living entities, including organisms such as bacteria, archaea, the mitochondria, the chloroplasts, and viruses (whether they exist or not of all of these entities is still debatable).

Initially, it was believed that nucleic acids were exclusively found in the nucleus of eukaryotic cells. In contrast to viruses, which often only carry one of the two components?DNA or RNA?all live cells include both DNA and RNA, with occasional exceptions, such as adult red blood cells. Nucleotide is the fundamental building block of biological nucleic acids.

It is made up of a phosphate group, a nucleobase, and a pentose sugar (either ribose or deoxyribose). Additionally, in the lab, solid-phase chemical synthesis and the utilization of enzymes (DNA and RNA polymerases) are used to produce nucleic acids. Chemical techniques also allow for the production of modified nucleic acids that are not present in nature, such as peptide nucleic acids.

Size and Composition of the Molecules

In general, nucleic acids are fairly big molecules. The largest known individual molecules are most likely DNA molecules. The size of well-studied biological nucleic acid molecules ranges from minuscule interfering RNA, which has 21 nucleotides, to big chromosomes (the human chromosome 1 is a single molecule with 247 million base pairs).

DNA and RNA molecules found in nature are typically single-stranded and double-stranded, respectively. There are many exceptions, though. For example, some viruses possess single-stranded DNA genomes while others have double-stranded RNA sgenomes. Additionally, under certain conditions, nucleic acid constructs with several strands can also form.

Nucleoside is the name given to the substructure that consists of nucleobase and sugar. The structure of the sugar in the nucleotides of different forms of nucleic acids varies; for example, whereas RNA includes ribose and DNA has 2'-deoxyribose, the sole distinction is the presence of a hydroxyl group. Adenine, cytosine, and guanine are all found in both RNA and DNA; however, thymine only occurs in DNA and uracil only occurs in RNA. The nucleobases found in the two separate nucleic acid types are also different.

Nucleic acids contain an alternating sequence of sugars and phosphates that are joined together by phosphodiester connections to form the so-called sugar-phosphate backbone. According to traditional nomenclature, the sugar's 3'end and 5'end carbons are where the phosphate groups bind.

The ends of nucleic acid molecules are known as the 5'-end and 3'-end because of this directionality in nucleic acids. The N-glycosidic linkage, which consists of the 1' carbon of the pentose sugar ring and the nitrogen of the nucleobase ring, connects the nucleobases to the sugars.

Topology

Complementary sequences are the building blocks of double-stranded nucleic acids, and Watson-Crick base pairing is used extensively in these sequences to produce a highly repetitive and uniform double-helical three-dimensional structure. Instead of being restricted to a standard double helix, single-stranded RNA and DNA molecules can adopt extremely complex three-dimensional forms that are built on brief segments of intramolecular base-paired sequences, which includes both Watson-Crick and noncanonical base pairs, as well as a variety of complex tertiary interactions.

It is possible for nucleic acid molecules to be linear or circular and are typically unbranched. For instance, while chromosomes in the eukaryotic nucleus are typically linear double-stranded DNA molecules, plasmids, mitochondrial DNA, and chloroplast DNA are often circular double-stranded DNA molecules.

Although circular and branched RNA molecules can emerge from RNA splicing events, linear, single-stranded RNA molecules make up the majority of RNA molecules. A double-stranded DNA molecule has an equal number of pyrimidines and purines in its overall makeup. The helix is about 20- in diameter.

Sequences

The sequence of nucleotides in each DNA or RNA molecule is what distinguishes one from the other. Since they contain the ultimate instructions that encode all biological molecules, molecular assemblies, subcellular and cellular structures, organs, and creatures, and directly enable cognition, memory, and behavior, nucleotide sequences play a significant role in biology.

Hundreds of millions of nucleotides are sequenced every day at genome centers and smaller labs around the world thanks to the enormous efforts that have gone into developing experimental techniques to determine the nucleotide sequence of biological DNA and RNA molecules.

Types of Nucleic Acids

1. Deoxyribonucleic Acid (DNA)

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions required in the growth and operation of every known living thing. Although the molecule DNA was discovered in 1869, its significance for genetic heredity was not made clear until 1943. Genes are the sections of DNA that contain this genetic data.

Other DNA sequences are involved in regulating the utilization of this genetic data or have structural functions. DNA is one of three primary macromolecules, together with RNA and proteins, that are necessary for all known forms of life. Nucleotides, which have backbones consisting of sugars and phosphate groups connected by ester bonds, make up the two long polymers of monomer units that make up DNA.

As a result of their orientation, which is antiparallel, these two strands are parallel to one another. Each sugar has a nucleobase, or base, which is one of four different types of molecules. The genetic code is included in the arrangement of these four nucleobases along the backbone. Using the genetic code as a guide, this information describes the amino acid sequence within proteins.

Transcription, a biological process, reads the code by copying segments of DNA into the associated nucleic acid RNA. Chromosomes, which are lengthy sequences of DNA, are how cells organize their DNA. The process of DNA replication during cell division results in the duplication of these chromosomes, giving each cell a full complement of chromosomes.

Animals, plants, fungi, and protists are examples of eukaryotic organisms. They store most of their DNA in the cell nucleus and part of it in organelles like mitochondria or chloroplasts. Contrarily, DNA is only stored in the cytoplasm of prokaryotes (bacteria and archaea).

2. Ribonucleic Acid (RNA)

A polymeric molecule called ribonucleic acid (RNA) is crucial for many biological processes, including the coding, decoding, control, and expression of genes. Nucleic acids include RNA and deoxyribonucleic acid (DNA). Nucleic acids are one of the four primary macromolecules required for all known forms of life, along with lipids, proteins, and carbohydrates.

The building blocks of RNA are nucleotides, just like DNA, however unlike DNA, RNA exists in nature as a single strand folded over itself rather than a paired double strand. The nitrogenous bases guanine, uracil, adenine, and cytosine, which are represented by the letters G, U, A, and C, are used by cellular organisms to transmit genetic information that instructs the creation of particular proteins through messenger RNA (mRNA). A large number of viruses use RNA genomes to encode their genetic material.

Some RNA molecules participate actively in biological processes within cells, either by regulating gene expression, catalyzing biological processes, or sensing and relaying responses to cellular signals. One of these ongoing activities is the production of proteins on ribosomes, which is a universal function controlled by RNA molecules. To do this, amino acids are transported by transfer RNA (tRNA) molecules to the ribosome, where ribosomal RNA (rRNA) joins the amino acids to create coded proteins.

3. Nucleic Acid Analogues

Nucleic acid analogues are substances that are structurally comparable to naturally occurring RNA and DNA and are employed in molecular biology research and treatment. Chains of nucleotides called nucleic acids are made up of one of four nucleobases, a phosphate backbone, a pentose sugar (either ribose or deoxyribose), and a pentose sugar (either ribose or deoxyribose).

Any of these could be modified in an analogue. Different base pairing and base stacking capabilities are typically conferred by analogue nucleobases, among other things. Examples include universal bases, which can pair with each of the four conventional bases, and analogs of the phosphate-sugar backbone, such as PNA, which modify the characteristics of the chain (PNA is even capable of forming a triple helix).

One of the cornerstones of xenobiology, the study of the construction of new-to-nature forms of life-based on different biochemistries, is the study of nucleic acid analogs, also known as Xeno Nucleic Acid. Peptide nucleic acids (PNA), Morpholino and locked nucleic acids (LNA), as well as glycol nucleic acids (GNA), threose nucleic acids (TNA), and hexanol nucleic acids (HNA), are examples of artificial nucleic acids.

Changes to the molecule's backbone allow each of these to be recognised from DNA or RNA that occurs in the body naturally. Researchers reported in May 2014 that they had successfully inserted two new artificial nucleotides into bacterial DNA and had been able to passage the bacteria 24 times by putting individual artificial nucleotides in the culture media.

However, they had not produced mRNA or proteins that could utilize the artificial nucleotides. Two joined aromatic rings could be seen in the synthetic nucleotides. Several nucleoside analogues are employed as antiviral or anticancer drugs. Incorporating these substances with non-canonical bases is the job of the viral polymerase. These substances are delivered as nucleosides because charged nucleotides cannot easily traverse cell membranes and must first be transformed into nucleotides in the cells in order to activate them.

The aberrant base found in the carcinogenic nucleotide analog BrdU, 5-bromouracil (5BU), is among the most widely used base analogs. However, it can spontaneously change into another isomer that couples with a different nucleobase, guanine, when a nucleotide containing 5-bromouracil is integrated into the DNA.

This isomer is more likely to pair with adenine when this occurs. In the event that this takes place during DNA replication, a guanine will be inserted as the analogous opposing base, and in the subsequent DNA replication, that guanine will mate with a cytosine. As a result, a transition mutation, which alters one base pair of DNA, occurs.