In a manual enzymatic DNA sequencing reaction,the nucleotide ddT is incorporated
A)at every T position in the synthesized DNA strand;the reaction is terminated when all T positions have been filled with ddT.
B)randomly at a single T position in the synthesized DNA strand,leading to termination of the reaction.
C)at several T positions in the synthesized strand,leading to termination of the reaction.
D)randomly at a A position in the template DNA strand,leading to termination of the reaction.

Question

Quizplus · Accepted Answer

In manual enzymatic DNA sequencing, the nucleotide analog ddT (dideoxythymidine triphosphate) lacks the 3'-OH group needed for further nucleotide addition. Therefore, when ddT is incorporated at a single T position in the synthesized DNA strand, the reaction is terminated, and a fragment of DNA is generated. This process is repeated with each of the four dideoxynucleotides (ddATP, ddCTP, ddGTP, and ddTTP) to generate a set of fragments complementary to the template DNA strand, which can be separated by size to deduce the sequence of the original DNA. So, option B is the best choice.

In a Manual Enzymatic DNA Sequencing Reaction,the Nucleotide DdT Is