Nucleotides

• What are the functions of nucleotides?

  energy for metabolism(ATP) , enzyme cofactors (NAD+) , signal transduction (cAMP) , precursors of nucleic acids
• What is a nucleobase?

  nitrogenous base
• What is a nucleoside?

  nitrogenous base and pentose sugar
• What is a nucleotide?


  Nitrogenous base + pentose sugar + phosphate
• What is the pentose sugar in DNA and RNA?

  B-D-ribofuranose in RNA

  B-2-deoxy-D-riobofuranose in DNA

  
• What is the characteristics of the phosphate group?

  Negatively charged at neutral ph , typically attached to 5' position (5'-triphosphates used to build nucleic acids) , nucleic acids contain one phosphate moiety per nucleotide
• What are the characteristics of nucleobases?

  Derivatives of pyrimidine or purines , nitrogen containing heteroaromatic molecules , planar , absorb UV 250-270nm
• What are the characteristics of pyrimidine bases?

  Cytosine is found in both DNA and RNA

  
  

  Thymine is found only in DNA

  
  

  Uracil is found only in RNA

  
  

  all are good H bond donors and acceptors , neutral molecules at ph 7
• What are the characteristics of the purine bases?

  Adenine and guanine are found in both RNA and DNA

  good H bond donors and acceptors

  Neutral molecules at PH 7
• What does Adenine look like?

  
• What does guanine look like?

  
• What does cytosine look like?

  
• What does thymine look like?

  
• What does uracil look like?

  
• What are the characteristics of the B-N-glycosidic bond?


  In nucleotides the pentose ring is attached via this bond

  
  

  Formed: anomeric carbon of the sugar in B configuration

  
  

  formed to position N1 in pyrimidines and position N9 in purines

  
  

  This bond is quite stable toward hydrolysis, especially in pyrimidines

  
  

  Bond cleavage is catalyzed by acid
• What is the UV absorption of nucleobases?

  250-270nm
• What are the names / codes of the deoxyribonucleotides?

  da/damp (deoxydenylate)

  
  

  dG/dGMP (deoxyguanylate)

  
  

  dT/dTMP (deoxythymidylate)

  
  

  dC/dCMP (deoxycytidylate)
• What are the codes/names of the ribonucleotides?

  A/AMP (adenylate)

  G/GMP (guanylate)

  U/UMP (uridylate)

  C/CMP (cytidylate)
• What are the minor nucleosides in DNA?

  modification is done after DNA synthesis , 5-methylcytidine is common in eukaryotes , N6-methyladenosine is common in bacteria

  Epigenetic marker
• What are minor nucleosides in RNA?

  Inosine: found in wobble position of the anticodon in tRNA

  
  

  Pseudouridine: found in trna and rrna , more common in eukaryotes