Question

* From your knowledge about DNA microarray, answer the following:

E- Using your own words, describe the color pattern outcome resulted at the end of the expression microarray experiment ?(2%)

F- If the expression microarray experiment was done with a normal sample and a suspected sample, after reading the color pattern resulted from the experiment it was recorded that “gene A22” is not expressed in the suspected sample. The gene A22 is expressed in all cells of the body but not expressed in colon cancer. Answer the following: What is the expected color of the spot on the microarray which represents this gene? What is your interpretation of the suspected sample; is it a cancer sample or not and explain why? (3%)

Answer 1

In Each type of cell different genes are expressed or silenced.If the cells that are turned on mutate,they could depending on on what role they play in the cell trigger the cell to become abnormal and devide uncontrollably,causing cancer.When a gene is expressed in a cell ,it generate mRNA .

In Microarray they will collect healthy cells and cancerous cells from patient.,this can helps to identify which gene are turned on and off in the healthy cells compared to cancerous cells.

The DNA copy is made from m RNA of from sample and then applied to microarray.cDNA binds to complementary base pairs in each of the spots on the array by hybridation.Based on how the DNA binds together ,each can spot will appear red ,green, or yellow when scanned with laser.

*A red spot indicates that the gene was expressed strongly in the cancer cells. *Green spot indicates that genes are strongly repressed in the cancer cells. *Yellow spot indicates that the gene neither strongly expressed nor strongly repressed. *Black spot indicates that none of the cDNA binds to DNA the gene located in the spot.

Based on given information. All body tissue samples in micro array noted as black because no cDNA binds to Norma DNA but colon cancer cells noted as green because of not expressed a22 gene.