DNATHE GENETIC MATERIAL

DNA is a macromolecule that forms a double helix structure in the cells(mostly in the nuclei and mitochondria) of living organism. The DNA molecule is considered the genetic material of all living cells. It is present in all organisms inhibiting life. It is responsible for determining the specific characteristics of an organism.

DNA was first observed by a German biochemist named Frederich Miescher in 1869. But for many years, researchers did not realize the importance of this molecule.

Many people believe that American biologist James Watson and English physicist Francis Crick discovered DNA in the 1950s.

Because of the three-dimensional shape of the structure they discovered, DNA has come to be described as a "double helix." A helix is a spiral shape, like a slinky or the hand rail of a spiral staircase

DNA is made up of molecules called nucleotides

Each nucleotide contains a phosphate group, a sugar group and a nitrogen base

The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C)

The sugars found in nucleic acids are pentose sugars; a pentose sugar has five carbon atoms.

Deoxyribose, found in DNA, is a modified sugar, lacking one oxygen atom (hence the name "deoxy"). 

The entire human genome contains about3 billion bases and about 20,000 genes.

.The single-ring nitrogenous bases, thymine and cytosine, are called pyrimidines, and the double-ring bases, adenine and guanine, are called purines.

 Cbonds with G and A bonds with T. It's called complementary base pairing because each base can only bond with a specific base partner. C will only bond with G and A will only bond with T in DNA. Because of complementary base pairing, the hydrogen-bonded nitrogenous bases are often referred to as base pairs.