ESTs are short (200–500 nucleotides) DNA sequences that can be used to identify a gene that is being expressed in a cell at a particular time.The Procedure:
- Isolate the messenger RNA (mRNA) from a particular tissue (e.g., liver)
- Treat it with reverse transcriptase. Reverse transcriptase is a DNA polymerase that uses RNA as its template. Thus it is able to make genetic information flow in the reverse (RNA ->DNA) of its normal direction (DNA -> RNA).
- This produces complementary DNA (cDNA). Note that cDNA differs from the normal gene in lacking the intron sequences.
- Sequence 200–500 nucleotides at both the 5′ and 3′ ends of each cDNA.
- Examine the database of the organism's genome to find a matching sequence.
- That is the gene that was expressed.
No comments:
Post a Comment