Card Set Information

2011-08-12 13:09:48

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  1. What is the primary function of Nucleic Acid?
    Store and transmit genetic information
  2. What are the 2 types of nucleic acid found in organisms?
    • Deoxyribonucleic Acid DNA
    • Ribonucleic Acid RNA
  3. Nucleic acid are macromolecules made up of?
  4. A structure of nucleotide
  5. Difference between DNA and RNA
    Hydrogen atom at Carbon Atom 2 in deoxyribose is replaced by an OH group in ribose
  6. 4 Bases categorised into?
    Purines and pyrimidines
  7. Difference between PURINES & PYRIMIDINES
    Purines have 2 rings while Pyrimidines have 1 ring in terms of STRUCTURE
  8. Purines are 2 RINGS
    • Adenine and Guanine
    • PUGA
  9. Pyriminidines are 1 RING
    Cytosine and Uracil (RNA) and Thymine

  10. Structure Reference
  11. How do nucleotides form?
    Condensation Reactions [water is removed during the process] 2 molecules of H2O
  12. Nitrogenous bases is linked to
    Carbon atom 1 of pentose sugar molecule
  13. Phosphoric acid is attached to
    carbon 5 of pentose sugar molecule
  14. What is a nucleoside?
    • Nitrogenous bases + pentose sugar
    • No phosphoric acid
  15. How polynucleotides are form?
    Formation of phosphodiester bond through condensation reactions!
  16. 5' end of polynucleotide ends with?
    A phosphate group attached to C5 of sugar
  17. 3' end of polynucleotide ends with?
    OH group C3 of sugar
  18. Process of formation of polynucleotide
  19. What is the structure of DNA?
    2 polynucleotide chains twisted around each other to form a double helix structure
  20. How do the 2 strands run?
    Anti parallel - opposite direction
  21. How is it held together?
    • Hydrogen bonds between nitrogenous base pairs of opposite strands.
    • Purine & Pyrimidine will always pair up
    • Complementary Base Pairing
  22. Adenine and thymine forms how many hydrogen bonds?
    2 TWO

  23. Cytosine and Guanine how many H bonds?
    3 THREE

  24. Ratio of A to T and C to G
    1 : 1
  25. 1 complete turn of DNA double helix
    • 10 base pairs
    • 3.4nm
    • Sugar phosphate backbone outside
    • Nitrogenous bases occupy centre of molecule
  26. Packing of DNA
    Most DNA wound around outside of grps of 8 histone protein molecules form nucleosomes

    • Remainder DNA (linker) joins adjacent nucleosomes
    • Nucleosomes and linkers > chromatin fibre

    Chromatin fibre coils around ITSELF form solenoid

    6 nucleosomes in 1 turn of solenoid

    Coiling of solenoid gives rise to chromatin

    Condensation of chromatin > chromosome
  27. Packing of DNA
  28. DNA REPLICATION wrt to base pair & H bond
    Double helical structure enables semi-conservative replication to occur

    During replication, 2 strands can unwind and separate

    Each strand act as template to which complementary set of nucleotides will attach by base pairing and hydrogen bonding

    Each original DNA molecule give rise to 2 copies of DNA with identical structure and base seq
    repair mechanims

    intact complementary strand can be used as template to guide repair

    repair ensure integrity of base seq of DNA molecule remains intact
  30. Stability of DNA molecule
    Bases held together by H bonds together with hydrophobic interactions btw stacked bases, stabilize structure

    • Adjacent nucleotides held together by strong covalent phosphodiester bond
    • Integrity of DNA base seq maintained