7.2 Function of DNA

• Properties of Hereditary Material

  • *Complete transmission*: Genetic information must be fully transmitted from one generation to the next along with the molecule.

  • *Consistency across cells*: All body cells of an individual within a species should contain the same amount of genetic material.

  • *Stability*: The genetic material must be exempt from major metabolic changes - its quantity should not fluctuate over time in cells of a given type.

  • *Information capacity*: It must be capable of storing the vast amount of information required to build a new individual.
• Hershey and Chase ( 1950) 


  • Stated that DNA is not a Protein
  • Studied the structure of bacteriophage for this study.
• James Watson and Francis Crick discovered the structure of DNA, which consists of two strands twisted around each other like a spiral staircase. Each strand has a sugar-phosphate backbone and pairs up with another strand using complementary base pairing rules (Adenine always pairs with Thymine, Cytosine always pairs with Guanine). This discovery revolutionized our understanding of genetics and led to further research into how genes are expressed and inherited.
• The structure of DNA was first proposed by James Watson and Francis Crick in 1953 based on X-ray diffraction data obtained by Rosalind Franklin and Maurice Wilkins at King's College London. Their work showed that DNA consisted of two antiparallel chains held together by hydrogen bonds between complementary bases.
• Andre Boivin and roger Vendrely 


  • Stated that body cells of a species contain the same amount of DNA
  • Done by measring the amount of DNA in cell nuclei from various species
  • DNA does not undergo metabolic changes
• Daniel Mazia's 


  • Stated that DNA content does not vary
  • Hereditary molecules must encode a huge amount of information.
• Clones

  • Organisms produced by asexual reproduction are genetically identical to the parent organism. They're essentially natural clones.
• Artificial cloning


  • This involves producing genetically identical organisms through laboratory techniques.
• Nuclear transplantation


  • A technique used in cloning where the nucleus of an unfertilized egg is replaced with the nucleus of a donor cell.
• Dolly the sheep


  • The first mammal cloned from an adult somatic cell in 1996. This breakthrough showed that specialized adult cells could be reprogrammed to create a new organism.
• Therapeutic cloning


  • A process aimed at producing embryonic stem cells for potential medical treatments. It involves creating an embryo genetically identical to a patient.
• Reproductive cloning


  • The creation of genetically identical animals. This has been successful with various species but remains controversial and inefficient.
• Human cloning


  • technically possible, it faces significant ethical, legal, and technical challenges. Many countries have banned human reproductive cloning.
• Differentiation


  • Subset of DNA, different forms and functions