Consider the ssDNA 5GCGC3 and duplex formation to dsdna Calc

Consider the ss-DNA 5\'-GCGC-3\' and duplex formation to ds-dna: Calculate Delta G Degree, Delta H Degree and Delta S Degree for this dimerization equilibrium Calculate the equilibrium constant, K for the dimerization at 310K Determine the concentration of ss-DNA, C_0, which must be added to solution so that the fraction (f) of DNA single strands in solution at equilibrium is: (i) f=0.5 f = 0.9 f = 0.1 What is (i) called, and why is it interesting?

Solution

i) when f=0.5 concentration of ssDNA will be 1

ii) when f=0.9;    concentration of ssDNA will be 0.2

iii) when f=0.1 concentration of ssDNA will be 1.8

Calculated from the formula: Co= [(1-f)Ct ] / 2

Ct can be calulated from the equation: Keq = (2f) /(1-f)²Ct ; where Keq obtained is 4.004

F is called the fraction of DNA single strands in solution.

when the solution containing DNA is denatured, the double helix structure unwinds to single stranded DNA. as such the UV absorption is increased and this property is called Hyperchromicity. This property can be used to track the changes in DNA strands.