NUCLEIC ACID {DNA AND RNA}

 History of Nucleic Acid

Nucleic acid was first discovered by Friedrich Miescher in 1869. He gave its first name as nuclein. In the early 1880s Albrecht Kossel further purified the substance and discovered its highly acidic properties. He later also identified the nucleobases.

WHAT IS NUCLEIC ACID

Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic acids are deoxyribonucleic acid and ribonucleic acid.

5-Carbon sugar--    Pentose is a monosaccharide (simple sugar) with five carbon atoms.

Phosphate group--  Phosphate groups are attached to the 5' carbon of a nucleotide and 3'                                            carbon of adjacent nucleotide in a DNA strand.

Nitrogenous base-- 

purines- (Adenine (A) and Guanine (G))

pyrimidine- (Cytosine (C) and Thymine (T)) 

These nitrogenous bases are attached to C1' of deoxyribose through a glycosidic bond. Deoxyribose attached to a nitrogenous base is called a nucleoside.

Types of nucleic acid--

There are two types of nucleic acids: DNA and RNA

1. DNA--deoxyribonucleic acid
2. RNA--Ribonucleic acid 

1.  DNA 

1.  DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA
2. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA)

2.  RNA

1. RNA- A polymer of ribonucleotides, is a single stranded structure. 
2. There are three major types of RNA- m RNA,t RNA and r RNA.

STRUCTURE OF DNA--

1. The structure of DNA is illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn 
2. Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (noncovalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C).

https://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/104573282/74---Copy_1_2.jpg