Microarrays

What do the probe nucleotide sequences represent in a microarray? The nucleotide sequences in microarrays are short sequences from genes from a particular organism. Some microarrays contain entire genomes but more commonly an array would contain a small number of short nucleotide sequences from each gene in the organism. These sequences are long enough to bind cDNA from a sample. If the cDNA has a sequence that is an exact match to one of the sequences on the chip it will bind strongly to that sequence. If there is a small number of base differences between the two binding will occur, but less frequently.

View the animation below, then complete the quiz to test your knowledge of the concept.


1	A microarray is a

		A)	ray of a small wavelength
		B)	a type of ultraviolet ray
		C)	an RNA probe used to identify viruses
		D)	an arrangement of oligonucleotide probes, closely arranged on a small solid support surface

2	A microarray commonly contains _______ nucleotides.

		A)	1–5
		B)	5–15
		C)	15–25
		D)	25–100
		E)	100–500

3	When interpreting the results of microarrays, the degree of hybridization between a given probe and an organism to be identified is measured by

		A)	turbidity read in a spectrophotometer
		B)	color intensity of an image produced by scanning with a laser beam
		C)	length of the probe formed
		D)	degree of agglutination
		E)	microscopy

4	When building a microarray, we know the sequence of the oligonucleotides, but not their position.

		A)	True
		B)	False

5	Nucleotides are made to attach to the glass by a light activation reaction.

		A)	True
		B)	False

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