Updated: Sep 2, 2021

For some people, the concept of DNA can be quite confusing. They often find themselves struggling to actually understand the basics. Well, in this blog I'll be talking all about it in the simplest and easiest way possible. First let's talk about DNA.

DNA or Deoxyribonucleic Acid is a type of genetic material( genetic material is a like a book of information for your body). DNA was first observed by Friedrich Meischer( a Swiss physician) in 1869. He called it Nuclein. However due to lack of technical resources, he could not investigate further.

DNA has three major components : a sugar, a phosphate group and a nitrogenous base.

SUGAR: DNA has a pentose sugar( 5-carbon ring or chain) known as deoxyribose( from ribose by loss of an oxygen atom).

PHOSPHATE GROUP: Chemically Phosphoric Acid( H3PO4). It makes the DNA negatively charged.

Nitrogenous Bases: These are primarily classified into 2 types.

The analogy to remember the nitrogenous bases is given above.

Structure of a nucleotide

Phosphate group--------- Sugar--------- Nitrogenous base

The bond between the phosphate group and sugar is known as a Phospho-ester bond.

The bond between sugar and nitrogenous base is known as a glycosidic bond

DNA is double helical structure. This was proved by James D Watson(American Molecular Biologist and Geneticist) and Francis Crick(British Molecular Biologist)

( Photo 51 was a DNA X-Ray Diffraction image taken by Raymond Gosling under the supervision of Rosalind Franklin( an English Chemist). This photo played a key role in determining of the double helix by Watson and Crick). James D Watson and Francis Crick were later awarded the Nobel Prize in Physiology or Medicine for this discovery. Rosalind however, was not awarded as she had died four years ago due to ovarian cancer at the age of 37.

The characteristics of the double helical DNA are

  • It is B form of DNA

  • It is double stranded i.e. it has 2 poly-nucleotide chains.

  • It is complementary i.e. a pyrimidine always bonds with a purine

  • The 2 strands of this DNA are anti-parallel meaning that if one strand of the DNA runs from 5'- 3', then the other strand will run in the direction 3'- 5'.

Chargaff's Equivalency Rule by Erwin Chargaff( American Biochemist)- According to this rule, the amount of purines is always equal to the amount of pyrimidines i.e. A+G=T+C

This is it for today. For deeper knowledge about these topics, make sure you regularly read my new blogs.

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