A scientist obtains the DNA sequence data for a bacterial plasmid. The data include As, Ts, and Gs, but no Cs. What is the most likely cause of this result?
A) ddCs were omitted from the sequencing reaction.
B) The cytosine deoxyribonucleotides were omitted from the sequencing reaction.
C) DNA polymerase was omitted from the sequencing reaction mix.
D) The ddG fluorescent tags were degraded.
E) There is no cytosine in this DNA molecule.

Question

A scientist obtains the DNA sequence data for a bacterial plasmid. The data include As, Ts, and Gs, but no Cs.  What is the most likely cause of this result?
A) ddCs were omitted from the sequencing reaction.
B) The cytosine deoxyribonucleotides were omitted from the sequencing reaction.
C) DNA polymerase was omitted from the sequencing reaction mix.
D) The ddG fluorescent tags were degraded.
E) There is no cytosine in this DNA molecule.

Quizplus · Accepted Answer

Omitting ddCs (dideoxycytidines) from the sequencing reaction would prevent the incorporation of these chain-terminating nucleotides at cytosine positions, leading to a lack of sequencing stops at Cs and thus no Cs being detected in the sequence data.

A Scientist Obtains the DNA Sequence Data for a Bacterial