WATSON AND CRICK's MODEL OF DNA - IDEA OF SELF REPLICATION

WATSON AND CRICK's MODEL OF DNA

Watson and crick suggested a model of DNA in 1953, which was based on X-ray, photographic and chemical analysis of DNA:
  • Watson and Crick suggested a ladder type organization of DNA. Each DNA molecule is made up of two polynucleotide chains which are twisted around each other and form a DOUBLE HELIX.
  • The upright of the ladder are made up of sugar and phosphate part of nucleotide and rungs are made up of paired nitrogenous bases.
  • ADENINE always pair with THYMINE and CYTOSINE always pair with GUANINE.
  • Two polynucleotides chains, which are complimentary to each other, are held together by HYDROGEN BONDS.
model of DNA

REPLICATION OF DNA

When the formation of new DNA molecule takes place in the cell without any change, it is known as replication of DNA.
  • DNA is able to duplicate itself in the chromosome.such duplication of DNA is called as REPLICATION of DNA.
  • During this process it makes an exact copy of itself.
  • The Watson and Crick model of DNA ideally proposed the idea of self replication.
  • The hydrogen bond that hold together the double helix of DNA are broken up.
  • Starting from the end like a zip,the double spiral gradually 'UNZIP' along its length and each new nucleotide of the proper kind would be added to the separated chain. 
                                         

BASIC STRUCTURE OF DNA                                              

CLICK HERE

 

 

Click Here