Principle
The core principle behind microarrays is hybridization between two DNA strands, the property of complementary nucleic acid sequences to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs. A high number of complementary base pairs in a nucleotide sequence means tighter non-covalent bonding between the two strands. After washing off of non-specific bonding sequences, only strongly paired strands will remain hybridized. Fluorescently labeled target sequences that bind to a probe sequence generate a signal that depends on the hybridization conditions (such as temperature), and washing after hybridization. Total strength of the signal, from a spot (feature), depends upon the amount of target sample binding to the probes present on that spot. Microarrays use relative quantization in which the intensity of a feature is compared to the intensity of the same feature under a different condition, and the identity of the feature is known by its position.
Read more about this topic: DNA Microarray
Famous quotes containing the word principle:
“The principle that human nature, in its psychological aspects, is nothing more than a product of history and given social relations removes all barriers to coercion and manipulation by the powerful.”
—Noam Chomsky (b. 1928)
“I do not mean to exclude altogether the idea of patriotism. I know it exists, and I know it has done much in the present contest. But I will venture to assert, that a great and lasting war can never be supported on this principle alone. It must be aided by a prospect of interest, or some reward.”
—George Washington (1732–1799)
“For me chemistry represented an indefinite cloud of future potentialities which enveloped my life to come in black volutes torn by fiery flashes, like those which had hidden Mount Sinai. Like Moses, from that cloud I expected my law, the principle of order in me, around me, and in the world.... I would watch the buds swell in spring, the mica glint in the granite, my own hands, and I would say to myself: “I will understand this, too, I will understand everything.””
—Primo Levi (1919–1987)