You have a well-funded research laboratory and want to study the double-stranded
ID: 512427 • Letter: Y
Question
You have a well-funded research laboratory and want to study the double-stranded DNA fragment below. Describe the steps you would go through to prepare this fragment (synthetically in the lab, not from a biological source.) What is the information content, in bits, of the top strand? Once made, you place this fragment into an aqueous solution containing 100 mM NaCl and 10 mM MgCI_2, at pH 8.0. You then measured the T_m for this fragment. What did you first estimate the T_m to be. and then, how did you go about measuring it experimentally? Lastly, you kept this fragment in solution in a test-tube on your bench-top for three years, and then re-measured the T_m, which was found to differ from what you measured a year ago. Give your best estimate for this new T_m, and propose an explanation for why it differed from the old measurement.Explanation / Answer
Problem # 1 YTGAAAGGAAGTGTGTTC Synthetically we can prepare by stem cells.this is the one strend of the DNA . when DNA is heated it is unfolded and separts the strends and we can say that hyderogen bonds are break during heating and denaturation takes place.
where, in general Guanine and cytocine having Three hydrogen bonds so the Melting temperature for these bases are higher than that of adnine and thymine .
Tm is the melting temperature which depends upon the length of the chain and the composition of the nucleotides. In general when the ncleotides contains more GC contaent so that DNA having higher Melting temperature.
On placing the strends into the solution of Nacl and MgCl2 and mesured the Tm . the Melting temperature is calculated as follows:
Tm= 2^o C(A+ T ) + 4^oC(G+C)
= 2( 5+ 5) + 4(6+1)
= 20+ 28
= 48 ^o C
If the strend is kept in a test tube for years and after that we will do again Tm so it sure that its will appears so different than before because the annealing takes place during many years and results are no longer same because bonds may break and cahnge the shape of the strends to .
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