Nucleic Acids 2

Nucleic Acids 2

1. Explain what is meant by polarity and its importance in the DNA metabolism

   • phosphate group in the 5' C side
   • OH- group in the 3' C side
   • for convienance the DNA and RNA are synthesised in the -> 5-> 3

2. Describe the structure of the DNA polynucleotide

   • Right handed
   • double helix
   • minor and major grooves
     • major grooves - where proteins bind to the DNA
     • minor grooves - sugar phosphate backbone
       • the side where the bases are present

3. Name the forces that stabilise the DNA structure

   • Base pairing by H-bonds
     • specificity
     • stabilityof nucleic acid structures
     • weak but collectively increase stability
   • Base- stacking interactions (since incsoluble in H2O)
     • planar palrallel molecules
     • hydrophobic interactions
     • Van der Waals
     • Stacking C&G bases are greater than T and A
   • ionic interactions
     • electrostatic interactions of charged phosphate groups and Mg2+ and Mn2+
     • istones +vely charged proteins

4. define supercoiling, explain its biological relevance and give an example of a clinical application of topoisomerase inhibitors

5. Describe 3 physical properties of DNA

6. Explain how the DNA is packed tightly in chromosomes

7. explain the role of histones in DNA packaging

8. Explain the term chromatin remodelling