Introduction:

Nucleic acids are a depository of genetic information. They hold the complete power to direct the cell and its functions. They carry all the needed information for cell division, protein synthesis, gene expression, and inheritance. Nucleic acids play a key role in the development, maintenance, and functioning of the human body. In this blog, we will learn in detail about what is a nucleic acid, the conformation of nucleic acid, types of nucleic acid, the structure of nucleic acid, the function of nucleic acid, DNA, RNA, and nucleic acid formula.

What is nucleic acid? 

Nucleic acids are carriers of genetic information. It was first discovered by Johann Friedrich Miescher in 1869. Multiple units of nucleotides (i.e., polynucleotides) are the building elements of nucleic acids. Nucleic acid is composed of three parts. They are:

• Sugars 
• Nitrogen Bases
• Phosphate

The major elements that serve as the basis of nucleic acids are hydrogen, oxygen, carbon, phosphate, and nitrogen. 

The structure of nucleic acid:

The structure of nucleic acid is formed by repetitive units of nucleotides. The nucleotide is formed as follows:

• The sugar molecule, 2′-deoxyribose, of DNA is a pentose sugar. The 2′ denotes the absence of the hydroxyl group from that five-carbon sugar and is replaced by the hydrogen group in the second carbon position.
• The nitrogenous base is of two types: Purine (Adenine, Guanine) and Pyrimidine (Cytosine, Thymine, Uracil). These bases are attached to the sugar molecule by β-N-glycosidic bonds. 
• Phosphate groups are attached to the sugar at the 5′-carbon position. Phosphate groups are named α, β, and γ units and are linked to sugar molecules by ester bonds. 

Each nucleotide is linked with the other through a phosphodiester bond that is formed between 3′ and 5′ carbons. 

The four levels of nucleic acid structure are as follows:

1. Primary structure 
2. Secondary structure 
3. Tertiary structure 
4. Quaternary structure.

Nucleic acid formula:

The nucleic acid formula and the formula of its other related components are as follows:

Nucleic acid = Sugar + Nitrogen Base + Phosphate. 

Nucleoside = Sugar + Nitrogen Base

Nucleotide = Nucleoside + Phosphate group

DNA = Deoxyribose + Phosphate group + Nitrogen Base (Adenine, Guanine, cytosine, and thymine).

RNA = Ribose + Phosphate group + Nitrogen Base (Adenine, Guanine, Cytosine, and Uracil).

Types of nucleic acid:

Nucleic acids vary, mostly differentiated based on the sequence of nucleotides. It is of two types:

• Deoxyribonucleic acid (DNA) 
• Ribonucleic acid (RNA) 

DNA:

DNA stands for Deoxyribonucleic acid. It is found in the nucleus or nucleoid of the cell and has deoxyribose as its sugar component. It is a long polymer that has adenine, guanine, cytosine, and thymine as nitrogenous bases (A, T, G, and C). Here, A pairs with T through a single bond, and G pairs with C through a double bond. It is double-stranded and shows a double helix structure. It can undergo replication on its own. 

RNA:

RNA stands for Ribonucleic acid. It is found in the cytoplasm of the cell and has ribose as its sugar component. It is shorter than DNA and has adenine, guanine, cytosine, and uracil as nitrogenous bases (A, U, G, and C). Here A pairs with U through a single bond, and G pairs with C through a double bond. It is single-stranded and forms secondary and tertiary structures. It is synthesized by DNA.  

Conformation of nucleic acid:

The conformations of nucleic acids are different for both DNA and RNA. 

• DNA conformation: DNA is a double-stranded polymer and the conformation of nucleic acid DNA is of three major types. They are 

1. A-form DNA: It is a right-handed helix and is 23Å in diameter. It forms wide and compact helices. 
2. B-form DNA: It is a right-handed helix and is 20Å in diameter. It forms thin and elongated helices. 
3. Z-form DNA: It is a left-handed helix and is 18Å in diameter. It forms a flat, long helix. 

• RNA conformation: The conformation of nucleic acid RNA varies based on the types of RNA present. They are:

1. Messenger RNA (mRNA): It is single-stranded and has start and stop codons. It also consists of a long poly (A) tail. 
2. Transfer RNA (tRNA): It is cloverleaf shaped and has three hairpins like loops. It has a T-arm, a D-arm, an anticodon arm, and an acceptor stem
3. Ribosomal RNA (rRNA): It is single-stranded and forms multiple loops within. They are dense and spherical. 

Functions of nucleic acid:

Nucleic acid is an important macromolecule required by our body for various functions. Some of the vital functions of nucleic acid are:

• Nucleic acids store and express genetic information.
• It acts as a storehouse of ATP 
• Nucleic acid Aids in protein expression
• They act as secondary messengers. 
• It assists cell signaling. 
• They act as a coenzyme.
• It transmits hereditary information.
• Nucleic acid assists cell division. 
• It supports cellular respiration.
• They aid in the immune response.
• It protects cell structure and function. 
• Nucleic acid contributes to growth and development.

Conclusion:

Nucleic acids are complex molecules that follow different sets of conformations and functions. Nucleic acids involve themselves in various crucial activities of the body. Recent research with nucleic acids is being applied in numerous fields like proteomics, genomics, metabolomics, oncology, medicine, genetic engineering, industries, etc.