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2012-09-08 13:50:25
Nucleotides biochem NSU

Introduction to Nucleotides
Show Answers:

  1. Which major nitrogenous bases are purines? Which are pyrimadines?
    • purines: adenine, guanine
    • pyrimadines: cytosine, thymine and uracil
  2. Can you tell teh structure of a purine from a pyrimidine?
    Purines have 2 rings while pyrimadines have 1 ring.
  3. What four bases are normally found in DNA? RNA?
    • DNA: adenine, thymine, cytosine, guanine
    • RNA: adenine, uracil, guanine, cytosine
  4. What are the 3 components of a nucleotide?
    nitrogenous base, sugar and a phosphate group
  5. Can you tell the chemical structure of a nucleotide from a nucleoside?
    A nucleoside does not contain the phosphate group.
  6. Can you tell the chemical structure of a ribonucleotide from a deoxyribonucleotide?
    A ribonucleotide contains hydroxyls which DNA does not have
  7. What is the modification of a normal base found in DNA that affects gene expression? What is a nucleotide that is not found in DNA or RNA that is important in energy metabolism? 
    The methylation od a cytosine silences the genome. ATP is important in energy metabolism. 
  8. What is the biochemical mechanism that enable coffee-drinking students to remain wakeful for lnoger periods of cramming?
    Caffeine inhibits the binding site of adenosine which is a depressant, therefore allowing for increased awake time
  9. What biological role do adenosine triphosphate and guanosine triphosphate have after being cyclized at their phsophates to form cAMP or cGMP?
    They serve as a secondary messenger inside the cell
  10. What is the difference between a nucleotide and a nucleic acid?
    A nucleic acis is a polymer of nucleotides.
  11. Why is it said that 2 strand of DNA run antiparellel?
    Because one strand runs from the 5' to 3' direction while the other one is 3' to 5'.
  12. How many hydrogen bonds are there in between an A-T pair? How many in a G-C pair?
    A-T have 2 hydrogen bonds when G-C have 3 hydrogen bonds
  13. What happens to DNA when it is exposed to temperatures of 94*C during a PCR procedure?
    THe DNA strands separate into individual strands
  14. A nucloside often makes a more useful drug than a nucleotide because a nucleoside
    is roughly hald the size of a nucleotide
  15. A patient is being given adenosine in response to life threatning cardiac arrythmia. ECG monitoring during the adenosine infusion indicate high-grade infusion does not solve the problem, which of the following should be given to reverse the effects of the adenosine?