What is the size of the PCR product when using specific primers for nucleotides 10-25 and 105-90?

To determine the size of the PCR product when using specific primers that anneal to distinct regions of the template DNA, you need to consider the positions of the primers on the DNA sequence. The first primer binds at nucleotides 10-25, meaning that it extends from nucleotide 10 to nucleotide 25. This results in a length of 16 nucleotides (25 - 10 + 1 = 16).

The second primer binds at nucleotides 105-90, which suggests that it is pairing in the reverse direction from nucleotides 90 to 105 on the complementary strand. When calculating the size of the product formed, you look at the distance between the two primer binding sites on the template, inclusive of both primer lengths.

The distance between nucleotide 25 (the end of the first primer) and nucleotide 90 (the start of the second primer) is (90 - 25) = 65 nucleotides. Then, you must consider the added lengths of the primers themselves (16 bp from the first primer + 16 bp from the second primer) to the length we already calculated.

Thus, the total length of the PCR product is 65 + 16 = 81 base pairs. However