Introduction to DNA Microarrays


DNA microarrays are created by spotting every gene in a genome onto a glass microscope slide.

RNA is isolated from two populations of cells. Two populations of RNA are converted to two colors (red and green) of cDNA.

cDNAs are hybridized with the microarray.

Microarray is washed and scanned for red and green cDNA.

Spots that bind to both cDNAs appear yellow.

Examples of real data.

See the Animation

Data Presentation

Data are collected as numerical values for each color and a red:green ratio is calculated.

Raw Ratios

Cluster Genes by Ratio Patterns

Tables of ratios are hard to read so cluster data and convert to new color scale.

Color-Coded Ratios

Real Data Clustered and Colored

(figure courtesy Pat Brown)

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