DNA: Definition, Structure, Function and Discovery

What is DNA?
”DNA, or deoxyribonucleic acid is the molecule that carries genetic information and pass if  from one generation to next.”
DNA is a complex molecules that contain all the information responsible for the development nd function of an organism. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA is found in a mitochondria (where it is called mitochondrial DNA).
 The information in DNA is stored as a code made up of four bases: adenine (A), guanine (G), cytosine (C), and thymine (T). DNA base pair up with each other, A with T and C with G, to form units called base pair. Each base is also attached to a sugar molecule and a phosphate molecule.
Our bodies have 3 billion genetic building block, or base pair, that make and only a tiny amount are unique to us, making us about 99.9% genetically similar to the next human.

DNA diagram
DNA Definition Structure Function and Discovery

Full form of DNA
DNA is a molecule that are carries genetical material information and pass if from one generation to another generation. ”Its full form is deoxyribonucleic.

Who discovered DNA
No one person discovered DNA, Instead, many scientists uncovered more and more about DNA. DNA was first discovered in 1869 by Swiss researcher Miescher. 
The 3-dimentional double helix structure of DNA molecules was discovered in 1953, Francis Crick and James Watson. In 1962, Watson and Crick were awarded the Nobel prize, together with Maurice Wilkins, for the discovery of DNA’s structure.

Types of DNA
There are three major forms of DNA are double stranded and connected by interactions between complementary base pair. Like
  • A-DNA
  • B-DNA
  • Z-DNA

A-DNA:- It is a right-handed double helix made up of deoxyribonucleotides. It is a similar to the B-DNA form. The two stands of A-DNA are anti-parallel with each other and not symmetrical. 

B-DNA:- The most common form, present in most DNA at neural pH and physiological salt concentration, is B-form. This is the right- handed double helical structure. It is made up of two antiparallel stands that are held together via hydrogen bonding in the A.T and G.C base pair.
Z-DNA:-  It is a left-handed double helix. It has a very different structure with compare A-DNA and B-DNA. Where the double helix winds to the left in a zig-zag pattern.  

DNA structure
Nucleotides are arranged in two long stands that form a spiral called a double helix. Each step of the ladder is a pair of nucleotides.
Each of the two stands is a long sequence of nucleotides or individual units made of:
  • a phosphate molecule
  • a sugar molecule called deoxyribose, containing five carbons
  • a nitrogen-containing region

There are four types of nitrogen-containing regions called bases:

  • Adenine (A)
  • Cytosine (C)
  • Guanine (G)
  • Thymine (T)

The order of these four bases forms the genetic code, which is our instruction for life.

The ‘rungs’ of the DNA ladder are each made of two bases, one base coming from each leg. The bases connect in the middle: ‘A’ only pairs with ‘T’, and ‘C’ only pairs with ‘G’. The bases are held together by hydrogen bond. 

Function of DNA
DNA is a play an important role in store genetic material in most living organism. It carries genetic information and pass generation to generation.
 Thus the following function include:
  • Storing generic material.
  • Replication-Transfer of genetic information.
  • Chromosome-Equal division of DNA during cell division. 
  • Recombination-During meiosis, crossing over gives rise to a new combination of genes.
  • Mutations-Variation and evolution.
  • Direct protein synthesis.
  • Determining genetic coding.


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