Hi guys, today we are going to discuss the thing that plays one of the major role in our body. Or we can say which carry the script for build requirements of body. For example the any protein which we require for proper functioning of body parts or for any other reasons. So friends many of us imagine that what is actually that, this is nothing but the DNA. Generally a double stranded DNA Which is one of the smallest part but playing major role in our body. Also the most important part in every research from field of biology or biotechology or genetic engineering. So guys let’s see what is DNA, its structure ? and how it is useful ?

What is DNA ?

So guys, first of all the long form of DNA is Deoxyribonuclic acid. Mainly it is one of the nucleic acid. Which conten two types of purine bases namely as adenine & guanine and two types of pyrimidine bases namely as cytocine & thymine.

After that DNA is one of the important part of our body or cell organelles, as they carry a code for synthesis of protein or which work as hereditary material in many of organisms. So it is located in cell nucleus. Which secure boundary for DNA.structure of DNA ?

Structure of DNA

So guys, DNA is the very long helical structure. Which contain alternate suger and phosphate groups. So let’s see how is it ?

Double helix structure

DNA contain two parallel stands. Which collide around a central, common and imaginary axis. Where it form a helical structure. And this structure was introduced by Watson and Crick.

Structure of stand

Stands are made up by the addition of many nucleotide i.e. polynucleotide chain. And the formation of nucleotide contain Lentos, deoxyribose auger, a phosphate group and nitrogen base.

Complementary pairing

We have four nitrogen bases i.e. two double ring purines and two single ring pyrimidines. As in DNA auger and nitrogen base are connect with glycosidic bond. Like that auger and phosphate are connect with phospo-diester bond. These are called 3′ -> 5′ phospho-diester linkage.

We know that purines and pyrimidines are complementary pairing. That is Adenine and Thymine are paired together with the help of double bonded hydrogen bond. And similarly Guanine and Cytosine paired together with the help of triple hydrogen bond. And this form a structure of rungs.

Purine : Pyrimidine ratio

Accourding two chargraff’s law, the total numbers of purines is equal to total numbers of pyrimidines i.e A+G=T+C. And the most important A+T is not equal to G+C but the ratio of this two quantities is always constant for same specie.

Polarity of strands

Guys, as we know that DNA consist of two strands. It has a polarity i.e one strands has polarity 3′ -> 5′ and another has 5′ -> 3′. And 3′ and 5′ are position of carbon atoms present in Penrose auger. And their polarity is based on free phosphate group present at 5′ end and free -OH group at 3′ end. Also because of this such arrangements one strand runs in 3′ -> 5′ direction, while other runs in 5′ -> 3′ direction. Hence these DNA strands are Also called as antiparallel strands.


As DNA has colloidal, helical structure it forms alternate major and minor groves. And this coiling is carried out in a right handed fashion.

Major and minor groves in DNA
Major and minor groves in DNA


DNA has diameter of around 2 nm with a deflection angle of 36° and this angle is between the angles of two rungs. Also the distance between two rungs is 3.4 A°. And the distance between two successive major or successive minor groves is about 10 rungs i.e. 10×3.4=34 A°. which complete a one spiral turn of DNA i.e. 36°×10=360° .

Why DNA is important for any organism..?

As we know that it carries script for synthesis of any protein. This protein is created with the help of RNA. And also it is important in heridity or inheritance. Which also help to designing shape of body and develop characters in our body as it carries many genes for proper functioning

So friends, it is all about DNA and it is amazing creation and also a wow structure by god.

Thank You..!

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