Question

Which of the following primers can amplify the following dna segment by pcr?

5'-gactggtcgcggatagcgtataatatttcggaatacggtatacccggatacggata-3'

a) 5'tatccgtatccgggtata and 3'gcgataggcgctggtcag
b) 3'gcgatacggatacggata and 3'atatgggcctatgcctat
c) 5'ataggcataggcatagcg and 5'ccgcgaccagtcggtata
d) 5'ctgaccagcgccatagcg and 5'gactggtcgcggggtata
e) 3'gcgatacggatacggata and 3'ctgaccagcgccggtata

Answer 1

Primer pair "d" is the correct answer as both primers are complementary to the ends of the target DNA sequence, with proper orientation for PCR amplification.

Step-by-step explanation:

The student is asking which pair of primers could be used to amplify a given DNA segment by polymerase chain reaction (PCR). PCR primers must be complementary to the ends of the target DNA sequence to be amplified. For primer selection, the 3' ends of the primers, in particular, must be complementary and bind to the template strands.

Reviewing the DNA segment and given primer pairs:

• Primer pair "a" is not fully complementary. The forward primer is complementary to the given sequence, but the reverse primer is not completely there.
• Primer pair "b" has the reverse primer written in the 3' to 5' direction; both primers should not have the same directionality.
• Primer pair "c" has both forward and reverse primers, but they are not complimentary to the ends of the target sequence.
• Primer pair "d" has primer sequences complementary to the ends of the target sequence, with the required antiparallel orientation.
• Primer pair "e" has both primers in the same direction and do not appear to have complimentary sequences at the correct ends.

Therefore, the correct answer is:

Primer pair "d": 5'ctgaccagcgccatagcg and 5'gactggtcgcggggtata