DNA Structure

  1. At physiological pH are nucleotides or nucleosides charged? Why?
    Nucleotides because of the negatively charged phosphate group
  2. conjugated bonds of purines and pyrimidines absorb UV light at what wavelength?
    260 nm
  3. Chargoff's rule
    amount of pyrimidines is equal to the amt of purines
  4. What molecule accounts for the repulsion between strands?
    negatively charged phosphate in the backbone
  5. Nitrogenous bases are attached to what carbon on teh ribose sugar?
    1 prime
  6. Hyperchromicity( absorbance of light) increases when
    • Upon denaturation via a change in pH, temperature, salt concentration
    • single strand has higher hyperchromicity because nitrogenous bases are exposed and their conjugate bonds are able to absorb UV light at 260 nm
  7. whats melting temp of DNA, what factors influence it?
    • melting temp is the temp at which half DNA is melted
    • cytosine= guanosine raises the melting temp of DNA
  8. Dideoxyribonucleotides are used in what procedure
    Sanger DNA sequencing
  9. Z helical conformation existis in regions of DNA that are rich in what nucleotides?
  10. A form of DNA is obtained how
    By dehydrating B form
  11. Whats the only form of DNA that has a Left helical rotation?
    Z form
  12. Histones are rich in what a.a , what charge do they have?
    arginine, lysine positively charged to offset the negative charge of phosphate groups
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DNA Structure
DNA Structure