Question

Large increase in absorption of UV radiation of 260nm by melted DNA duplex is called
a. Gaidukov Phenomenon
b. Position Effect
c. DNA Compaction
d. Hyperchromic effect

Answer 1

Hint: This outcome leads to the striking boost in the absorbance of DNA upon denaturation. The two strands of DNA are joined together mainly by the stacking interactions, hydrogen bonds, and hydrophobic effect amid the complementary bases. In this, the hydrogen bond stops the resonance of the aromatic ring so the absorbance of the sample is shrunk as well.

Complete answer:
In the Gaidukov phenomenon, the stain composition changes to amplify its efficiency for the highest acceptance of light. Position Effect is the adjustment in the expression of a gene or genetic region due to its transfer within the genome as a product of inversion or translocation. DNA compaction directs to the process of constructing DNA molecules invitro or invivo.

Hyperchromicity is the amplification of absorbance (optical density) of a substance. The most well-known example is the hyperchromicity of DNA that happens when the DNA duplex is denatured. The UV absorption is boosted when the two single DNA strands are being separated, either by heat or by the accumulation of denaturant or by mounting the pH level. The opposite, a shrink of absorbance is called hypochromic.

Hence, the correct answer is option (D).

Note: When the DNA double helix is treated with denatured agents, the contact force holding the double-helical structure is ruptured. The double helix then separates into two single strands which are in the arbitrary coiled conformation. During this time, the base-base interaction will be declined, boosting the UV absorbance of the DNA solution because many bases are in liberated form and do not make hydrogen bonds with complementary bases. Consequently, the absorbance for single-stranded DNA will be 37% advanced than that for double-stranded DNA at a similar concentration.