Review of Nucleic Acids

• Nucleic acids + Amino acids + Carbohydrate + Lipid = Life

  
• Types of nucleic acids

  • Deoxyribonucleic acid (DNA)
  • Ribonucleic acid (RNA)
  • Energy reaction

  
• Nucleic acids


  Have different functions, from storing the genetic information (DNA), structural/catalytic function (r-RNA) to directing the synthesis of proteins (m-RNA, t-RNA). In addition some nucleic acids serves as energy reaction molecules (ATP, NAD, FAD).

  
• DNA


  • Stores the genetic information (ex.: to make protein)
  • Double helix: two polynucleotide strands connected by hydrogen bonds
  • The complementary strands of DNA are "antiparallel"
  • The 5' end of one strand is the 3' end of the other
  • The paired chains of nucleotides twist together into a double helix

  
• RNA


  • Similar to DNA except the nucleotides: 1) Contain Ribose sugar instead of Deoxyribose, 2) Include the base uracil instead of thymine, 3) Single polynucleotide strand

  
• RNA functions


  1. Messenger RNA (m-RNA) transfers information from DNA to the ribosome

  2. Ribosomal RNA (r-RNA) is the structural part of the ribosome and have catalytic function

  3. Transfer RNA (t-RNA) carries amino acids to the ribosome

  
• Polymer


  Nucleic acids
• Nucleotide


  • Pentose sugar
  • Phosphate group
  • Nitrogenous base
• Backbone


  • Phosphate group + sugar
  • Linked together by phosphodiester bonds
  • Links are made on carbon C-5 and C-3 of the sugar, giving the direction of the DNA 5' to 3'

  
• DNA synthesis


  Polymerase enzyme adds nucleotides, one by one, only to the free hydroxyl 3' end (OH) of a growing DNA strand (5' → 3')

  
• Nitrogenous bases


  • Purines: Adenine (A) and Guanine (G)
  • Pyrimidines: Cytosine (C), Thymine (T) and Uracil (U) (Only in RNA)

  
• Guanine (G) was first isolated in 1844 from guano (excreta of sea birds)
• Uracil (U) was named in 1885 by a German chemist, who was attempting to synthesize derivatives of uric acid. Uric acid is found in urine.
• Thymine (T) was first isolated in 1893 from calf thymus glands. The thymus is a specialized organ of the immune system.
• Cytosine (C) was first isolated in 1894 from calf thymus glands.
• Adenine (A) named in 1885 after Greek ἀδήν aden "gland", in reference to the pancreas, from which it was first extracted. Pancreas is an organ of the digestive system and endocrine system.
• Complementary base-pairing rules


  • Adenine (A) with Thymine (T) (2x H bonds)
  • Guanine (G) with Cytosine (C) (3x H bonds)

  
• ATP


  • Primary energy currency of the cell
• NAD and FAD


  • Electron carriers for many cellular reactions
• Describe DNA?

  Function: store genetic information

  Double helix formation (hydrogen bonds)

  Adenine goes with Thymine

  Guanine goes with Cytosine
• What type of bond links the 5' and 3' in the backbone?

  Phosphodiester bonds, which are ester bonds that form between a sugar and a phosphate group to create the backbone of a nucleic acid.