6. Two double-stranded fragments of DNA are exactly the same length. At 89°C, fragment A has completely denatured, which means that the two strands have separated. At that temperature, fragment B is still double-stranded A. How might these fragments differ, to result in different denaturation temperatures? (2 points) B. Determine the nucleotide composition of fragment A. (4 points)

A. fragment A has   lower proportion of G-C which has 3-Hydrogen bonding,(high energy bonding) but more of A-T bonding of 2-Hydrogen  bindings(low energy bonding).  Therefore denatures at 89 degree,Lower bonding energy allow denaturation at low temperature .

B.  There is likelihood of fragment A having  high proportion of A-T,  but lower proportion of  fragment G-C,

Structurally   the G-C  hydrogen bonds is three  in number, while 2 hydrogen bonds joined n A-T bases. This variation in number of  hydrogen bonding ensures stability of Guanine-Cytosine bonds and therefore high resistance to heat compare to Adenine-Cytosine bonds.

Consequently, fragments A must contain  higher proportion of  lower hydrogen number A-T complementary bases, compare to higher  number of H-bonding Guanine-Cytosine Base complementary.thus low energy, with low  resistance to heat, and therefore unwinding of its double helix.

However, the higher proportion of G-C compare to A-T in  fragment B , aids its high resistance to heat, high temperature to overcome the high bonding energy  and therefore  its stability to heat, and failure to unwind at the same temperature,

Explanation:

a.) a destruction fo cells by viral reproduction