BIMM110 - LECTURE 28
DNA MICROARRAYS
A. General Introduction to Microarrays
a good place to start is to search the Internet, and the following are some examples
Note the definition of probe vs target: usually we have a mixture of DNA or RNA molecules separated on a gel/blot and we probe with a single probe made radioactive or with a chromophore attached
in microarray technology we have
hundreds or even thousands of specific probes, each at a specified location
on a grid; each represents a unique sequence from a known gene
the probes are usually cDNA fragments spotted on the grid by robotic techniques
alternatively, specific oligonucleotide sequences can be synthesized directly
on the grid (again with robotic techniques)
the target in microarray technology is a mixture of cDNAs (one strand, or denatured) made by reverse transcriptase from the mRNAs of two types of cells: a "control" (reference) and a tissue of interest (e.g. a tumor); they are differentially labeled with either a red or a green fluorophore, and what is eventually measured at each spot is the ratio of red to green, i.e. we measure the relative abundance of each mRNA. This indicates which genes are overexpressed and which genes are underexpressed in the tumor cell relative to the reference cell.
B. Application in Cancer Biology
1. Identifying the tissue of origin
2. Correlation of gene expression in a cancer cell with effectiveness of certain drugs
3. Estimation of survival rates after surgery/chemotherapy/radiation
http://www.gene-chips.com/GeneChips.html#What