Concept explainers
Interpretation:
The experiments that needs to be designed to determine the factors affecting the DNA double helix structural stability needs to be explained.
Concept introduction:
The stability of a DNA double helical structure depends on the hydrogen bonding between bases and base-stacking interaction between adjacent bases.
The bases present in a single strand of DNA have polar amido, amidino, guanidino and carbonyl groups which form hydrogen bonds with water, but when the double helical structure is formed some of the bond breaks as the bases combine to form inter-base hydrogen bonds. The change in enthalpy, in this case, is due to the difference of energy in the new hydrogen bond formed and old hydrogen bond is broken.
The stability of base stacks of the double helix depends on the DNA sequence. Some sequences are more stable than others, hence the nearest base stack is important to state the stability of the double helical structure.
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Biochemistry
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- Write a balanced equation for the hydrolytic deamination of a DNA5-methylcytosine residue.arrow_forwardBiochemist Erwin Chargaff was the first to note that, in DNA, [A] = [T] and [G]= [C], equalities now called Chargaff’s rule. Using this rule, determine the percentages of all the bases in DNA that is 20% thymine.arrow_forwardAssuming the average weight of a deoxynucleotide monophosphate (dNMP) is 327.0 g/mol, how many picomoles of DNA are present in 500ng of a 1000bp DNA fragment?arrow_forward
- A duplex DNA molecule contains a random sequence of the four nucleotides with equal proportions of each. What is the average spacing between consecutive occurrences of the sequence 5'-ATGC-3'? Between consecutive occurrences of the sequence 5'-TACGGC-3'?arrow_forwardWhat two enthalpic factors stabilize DNA in double-helical form at low temperature?arrow_forwardWhat two basepair changes can occur when G tautomerizes to the enol form? Recall that the tautomerization can occur when G is a free dNTP prior to DNA replication or when G is incorporated into dsDNA just before DNA replication. Draw both of these bp changes out. Are they transitions or transversions?arrow_forward
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