Explain the use of DNA microarrays in genetic testing or diagnosis.

a. used to test the presence or absence or a gene/allele
OR
used to diagnose the presence of a particular strain of virus/bacteria
OR
used to diagnose the presence of a specific mutation
OR
used to diagnose the presence of an expression of genes ✔

b. DNA spots/probes/sequences attached to solid surface/microarray ✔

c. mRNA from healthy tissue/cell isolated and converted to cDNA
OR
mRNA from cancer tissue/cell isolated and converted to cDNA ✔

d. conversion to cDNA by reverse transcriptase ✔

e. fluorescent dye linked to complementary DNA/cDNA ✔

f. cancer cDNA colored with a different dye from the healthy cDNA ✔ Accept named colour.

g. cDNA binds to/hybridizes with probes «that have complementary base sequences» ✔

h. microarray rinsed to remove cDNA that has not hybridized ✔

i. microarray exposed to laser light which causes dye to give off light ✔

j. fluorescence shows which probes have hybridized
OR
fluorescence shows which sequences were in the tissue/sample ✔

k. hybridized probe shows gene expression
OR
hybridized probe helps in diagnosis of disease ✔