Nucleic acid

• Transcription


  The process of copying genetic information from DNA to RNA
• Translation


  The process of using the information in RNA to produce proteins
• Main groups of molecules involved in living systems

  • Nucleic acids
  • Carbohydrates
  • Proteins
  • Lipids
• Nucleic acids

  Encode all of the genetic information for an organism
• Types of nucleic acids

  • DNA - Deoxyribonucleic acid
  • RNA - Ribonucleic acid
• Flow of information in a cell

  1. DNA

  2. RNA

  3. Transcription

  4. Protein

  5. Translation
• Nucleotides

  The building blocks of nucleic acids (DNA and RNA)
• Components of nucleotides

  • Phosphate group
  • Sugar (ribose or deoxyribose)
  • Nitrogenous base
• Nitrogenous bases

  • Purines (Adenine, Guanine)
  • Pyrimidines (Cytosine, Thymine, Uracil)
• Nucleoside triphosphates


  The monomers used in the synthesis of nucleic acids
• Synthesis of nucleic acids

  1. Nucleoside triphosphate

  2. Pyrophosphate

  3. Growing nucleic acid (n residues)

  4. Growing nucleic acid (n+1 residues)
• Phosphodiester link


  The bond that joins the hydroxyl group on carbon-3' of one sugar to the hydroxyl group on carbon-5' of the next
• Polynucleotide chain direction

  One end has an unreacted 5' phosphate, the other end has an unreacted 3' hydroxyl group
• The base sequence is always written in the 5' to 3' direction
• The backbone of DNA and RNA consists of sugar units linked by phosphate groups
• DNA double helix

  • Has a constant diameter (2nm)
  • There are 10 nucleotides per turn of the helix
  • The phosphate groups and the sugars lie on the outside of the helix next to the water environment
  • The bases lie flat on the inside of the helix and form hydrogen bonds between the two strands
  • Van der Waals bonds form between successive bases on the same strand
  • The strands run in opposite directions
  • The two strands are complementary
• Watson and Crick analysed X-ray diffraction patterns from DNA fibres and deduced the structure of the DNA double helix in 1953
• Base pairing rules in DNA

  Adenine pairs with Thymine, Guanine pairs with Cytosine
• The structural differences between DNA and RNA are the sugar (deoxyribose in DNA, ribose in RNA) and the nitrogenous base (Thymine in DNA, Uracil in RNA)
• Types of nucleic acids:

  DNA

  RNA
• Difference between DNA and RNA: DNA is a double helix, RNA is a single strand, bases in DNA are C, G, A, T and RNA are C, G, A, U
• Difference between a purine and pyrimidine:

  purine is double ring/
• What are the monomers used in the synthesis of nucleic acids?

  nucleoside triphosphates
• how is the phosphodiester link made?

  hydroxyl group on the carbon-3' of a sugar is joined to the hydroxyl group on carbon-5' of the next
• What order is the base sequence written in?

  5' to 3'