In the dideoxy method of DNA sequencing, the dideoxy analog
A) allows specific chemical cleavage of the DNA strand at random sites.
B) is required for the synthesis of the primer.
C) causes termination of DNA chain elongation.
D) cannot be utilized by DNA polymerase.
E) lacks a 5' phosphate group.

Question

Quizplus · Accepted Answer

The dideoxy analog (ddNTP) lacks a 3'-OH group, which is necessary for the formation of the phosphodiester bond between the nucleotides during DNA chain elongation. When a ddNTP is incorporated into a growing DNA chain, it causes chain termination because no further nucleotides can be added. This results in the production of a set of DNA fragments that are terminated at different positions, with each fragment terminating at the position of the ddNTP that was incorporated. By using a set of four ddNTPs, each labeled with a different fluorescent dye, along with the standard nucleotides, one can generate a set of fragments that are each terminated at a specific nucleotide position, allowing the sequence to be read.

In the Dideoxy Method of DNA Sequencing, the Dideoxy Analog