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13 Cards in this Set

  • Front
  • Back
What does a nucleotide consist of?
a heterocyclic nitrogenous base (purine or pyrimidiine),
a pentose sugar (ribose or deoxyribose (furanose form) and
a phosphate group
All the bases strongly absorb UV light at...
250-276nm, 260nm peak
what is the difference between a ribonucleoside and a deoxyribonucleoside?
What is the difference between a nucleoside and a nucleotide?
A deoxyribonucleoside has a oxygen missing @ 2 position.

Nucleoside = base + sugar
Nucleotide = base + sugar + phosphate
How many negative charges does a nucleoside-triphosphate have?
4 negative charges. one each on alpha and beta phosphate and two on gamma phosphate.
Which bond joins the base to the sugar in a nuclotide?
beta-N-glycosidic bod between C1 of ribose and N of base (N1 of pyrimidines and N-9 of purines)
What is the main difference between purines and pyrimidines? List examples of each.
Purines have a double ring structure and pyrimidines have a single ring structure.
Adenine and Guanine are purines.
Uracil, Thymine, and Cytosine are pyrimidines.
Two strands of DNA are held together by what type of bonds between which bases?
Hydrogen bond between A-T and G-C. G-C forms a triple hydrogen bond and therefore it's stronger.
What is the diameter of the watson/crick double helix? How many base-pairs per turn?
10.4 bp/turn
At what site of the DNA do the proteins bind to the DNA?
proteins bind at major and minor groove caused by glycosidic bonds on both strands, which are not directly across from each other.
Increase in which bonds of DNA increases the melting temperature of DNA?
Increase in G-C content increases melting temperature of DNA. Because of the triple hydrogen bonding of G-C compared to double hydrogen bonding of A-T.
What is viscosity? What happens to the DNA viscosity when it is denatured?
Viscosity if the material's resistance to flow.
Viscosity decreases as DNA is denatured.
Clinal correlation:
AZT (Zidovudine)
5-Fluorouracil - cancer therapy. converted to FdUMP which inhibits thymidylate synthase.

AZT - AIDS treatment. inhibits replication of HIV

Acyclovir - inhibits DNA polymerase of Herpes Simplex.
Clinical correlation:
Adenosine (Adenocard)
Azathioprine - metabolized to 6-mercaptopurine which suppresses rejection during organ transplant.

Allopurinol - treatment of gout

Adenosine - treat supraventricular tachycardia.