The estimated half-life for P-O bonds is 1.3 x 105 a (a = annum = year). Approximately 109 such bonds are present in a strand of DNA. How long (in terms of its half life) would a single strand of DNA survive with NO cleavage (in the absence of DNA repair enzymes)?

a) It is known    that    double    stranded    DNA    is    denatured    at    low    pH.     pKa values    should    allow    the    determination    of    whether    this    is    due    to    perturbation    of    the    hydrogen    bonding    in    A-T    and/or    G-C    base    pairs.    The    table    gives    values    for    the    pKas    of different    protonated    groups    in    the    nucleobases.Nucleobase Position    &    pKa                    A             N1,            3.5                    G             N7,            1.6;                N1,    9.2                    C             N3,        4.2                    T             N3,        9.7a)   Draw    the    A-T    and    G-C    base    pairs.                - Label    the    bases    with    the    one-letter    code.    –        - Number    the    atoms    in    the    rings and    label    the    atom    that    attaches    to    the    sugar.                - Mark the groups that interact in normal…

The A and G compositions (mole percent) of one of the strands of a duplex DNA is A = 27 and G = 30. (a) What would be the T and C compositions of the complementary strand? (b) What can be said about the A and G compositions of its complementary strand?

Discuss the following statement: “the DNA repair enzymes that fix deamination and depurination damage must preferentially recognize such damage on newly synthesized DNA strands.”