You want to amplify a 21 kb portion of your favorite gene fr
You want to amplify a 2.1 kb portion of your favorite gene from genomic DNA using PCR. The sequence of the two ends of the coding strand is as follows:
5’- CTCCATGGTAAACTTGTACT . . . [2060 bp] . . . GGTCATATAGCTGGATAACT -3’
Which of the following pairs of primers could be used to amplify the gene by PCR?
Which of the following pairs of primers could be used to amplify the gene by PCR?
| A 5’-GAGGTACCATTTGAACATGA-3’ and 5’-GGTCATATAGCTGGATAACT -3’ | 
| B 5’-AGTACAAGTTTACCATGGAG-3’ and 5’-GGTCATATAGCTGGATAACT -3’ | 
| C 5’-CTCCATGGTAAACTTGTACT -3’ and 5’-CCAGTATATCGACCTATTGA-3’ | 
| D 5’-CTCCATGGTAAACTTGTACT-3’ and 5’-AGTTATCCAGCTATATGACC-3’ | 
Solution
(B) 5’-AGTACAAGTTTACCATGGAG-3’ and 5’-GGTCATATAGCTGGATAACT -3’
The PCR amplification reaction requires 2 primers for a region of sequence to be. The forward primer is designed along one strand in the direction toward the reverse primer. Likewise, the reverse primer is designed from the complimentary strand. In this instance, the forward primer is the one that is in an exact complement to the strand to be amplified. Hence, the primer which is complementary to the coding strand of CTCCATGGTAAACTTGTACT is AGTACAAGTTTACCATGGAG. Hence option B.

