According to the sequence below (note that the DNA is written in the 5' $\rightarrow$ 3' direction, and the gene of interest is underlined), the BEST forward primer to use for this gene is:
A) 5' GGTTTGAATCAAATGGCTGA 3'.
B) 5'ATGACTGATACATCATCCTC 3'.
C) 3' ATGACTGATACATCATCCTC 5'.
D) 5' GAGGATGATGTATCAGTCAT 3'.
E) 3' GAGGATGATGTATCAGTCAT 5'.

Question

According to the sequence below (note that the DNA is written in the 5' $\rightarrow$ 3' direction, and the gene of interest is underlined), the BEST forward primer to use for this gene is: 
A) 5' GGTTTGAATCAAATGGCTGA 3'. 
B) 5'ATGACTGATACATCATCCTC 3'. 
C) 3' ATGACTGATACATCATCCTC 5'. 
D) 5' GAGGATGATGTATCAGTCAT 3'. 
E) 3' GAGGATGATGTATCAGTCAT 5'.

Quizplus · Accepted Answer

The best forward primer would be a short sequence of 18-22 nucleotides that is complementary to the 3' end of the gene of interest. In this case, the underlined region of the gene is in the 5' to 3' direction, so we need to look for a forward primer that is complementary to the 3' end. Option B has a sequence that is complementary to the 3' end of the gene and is a good length for a primer. Option A, D, and E have sequences that are not complementary to the 3' end of the gene, and option C is in the opposite orientation.

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