Question

The key ingredient for Sanger (dideoxy) sequencing is ddNTPs because:

a) They synthesize the DNA resulting in fragments that differ in length by one nucleotide
b) They are incorporated into DNA being synthesized, resulting in elongation of the DNA fragment
c) They prevent further DNA synthesis, and when added at the appropriate ratio will result in DNA fragments that differ in length by one nucleotide
d) They act as a primer, annealing to the starting DNA and allowing DNA polymerase to bind

Answer 1

The key ingredient for Sanger sequencing is ddNTPs because they prevent further DNA synthesis, resulting in DNA fragments that differ in length by one nucleotide.

Step-by-step explanation:

The key ingredient for Sanger (dideoxy) sequencing is ddNTPs because: c) They prevent further DNA synthesis, and when added at the appropriate ratio will result in DNA fragments that differ in length by one nucleotide. The ddNTPs, or dideoxynucleotides, lack a free 3' OH group needed for further nucleotide addition, causing synthesis to terminate when incorporated into the DNA strand. By using a predetermined ratio of deoxynucleotides to dideoxynucleotides, different size fragments can be generated.