1. Gene Chips

2. Used to measure the expression of thousands of genes at one time
All cells in our body have the same genes , but not all genes are expressed in all cells.
Neuron look different than epithelial cells
Some genes are up-regulated, down regulated, turned off (inactive)

3. Change in the transcription (expression) of genes in cells helps in understanding abnormal and normal aspect of cell function
Changes in transcription in cancer cell and normal cell.
First step is to make a gene chip (DNA chip, microarray)
In an arranged pattern spots are made on a slide

4. Each spot has many copies of specific gene from the genome of the cell.
mRNA from cancerous and non cancerous cells, which is then used to make cDNA - probes
Cancerous and noncancerous cDNA are labeled with different color dyes – hybridization solution – cDNA of all the genes
Solution added to the spots

5. Look for hybridization of the probes to each gene spot on the chip
Intensity of the color of each spot after hybridization indicates the extent to which each gene is expressed
Determine the pattern of gene expression
Which genes might be important in the development of cancer
Identify these genes years sooner than using other DNA technologies (southern blotting)

6. A gene chip has more than 30,000 spots
6 genes to study expression of these genes in normal and cancerous cells
Inactive, down regulated – allowing cancer cell to grow
Up-regulated – making the cells cancerous
Normal cDNA – blue (green)
Cancerous cDNA – pink (red)

7. More in cancer –red (pink)
Same in both cells – yellow (purple)
Inactive – colorless
More in normal – green (blue)