The Specificity of Nucleic Acid Hybridization Is Remarkable

question 22

Multiple Choice

The specificity of nucleic acid hybridization is remarkable. Even a single mismatch between a probe and a target sequence can be detected depending on hybridization conditions. This sensitivity can be employed in applications such as SNP haplotyping. Consider a probe that is complementary to a 20-nucleotide-long genomic region including a single polymorphic nucleotide. The probe is perfectly complementary to the more common allele, but has one mismatch in the case of the minor allele. The temperature-dependent hybridization of the probe to the single-strand genomic fragment is schematically presented in the following graph. To detect hybridization, a fluorescent dye is added to the reaction. The dye fluoresces strongly only when intercalated between the bases of double-stranded DNA, and is therefore used to quantify double-strand formation or dissociation. Which "melting curve" (1 or 2) in the graph do you think corresponds to the more common SNP allele? Which curve shows a higher melting temperature?

• A) 1; 1
• B) 1; 2
• C) 2; 1
• D) 2; 2

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Definitions:

Poison Pill

A defensive strategy used by companies to prevent or discourage hostile takeovers by making the company less attractive to the acquirer.

Golden Parachute

Substantial benefits given to top executives if the company is taken over by another firm, serving as a deterrent for unwanted takeovers.

Unfriendly Takeover

An attempt by one company to acquire control of another company without the consent or cooperation of its management or board of directors.

Going-private Transaction

A process by which a publicly traded company is transformed into a privately-held entity, usually through a buyout or acquisition.