One of the most powerful new techniques for analyzing gene expression en masse is that of microarrays
How can this method be used to ascertain all the changes in gene expression that occur in normal breast tissue and tissue taken from a breast cancer tumor?
What will be an ideal response?
Ans: Microarrays are constructed using 20-25 bp oligonucleotides representing the DNA sequences of the 25,000 known human genes which are spotted onto a glass slide, in a specific pattern of rows and columns. The mRNAs from the normal and breast cancer tissues are isolated, converted to single stranded cDNA copies, with the two sample sets each containing a different colored fluorescent tag on the cDNA. The tagged cDNAs are allowed to hybridize with their corresponding oligonucleotides, and the relative differences in hybridization are determined by comparing the relative intensities of the two tags. The data are then displayed as the difference in hybridization for each spot on the chip which reflects the abundance of the mRNAs for each gene in the two samples.
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When you look at a bone, you see solid bone. What is inside the bone?
What will be an ideal response?
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