Q: In ddNTP DNA sequencing, dideoxynucleotides are used to terminate the replication of DNA strands which can then be analyzed for their length on gel electrophoresis. The ddNTPs are missing both their 2' and 3' hydroxyl groups. Which of the following reasons best explains why ddNTPs terminate the DNA replication?
A		Nucleotides must have a 3' hydroxyl group for extension of the fragment to occur.
B		Nucleotides must have a 2' hydroxyl group for extension of the fragment to occur.
C		The loss of two hydroxyl groups makes the terminal end of the DNA nonpolar and thus unable to continue extending.
D		ddNTPs are always used by cells for termination of their DNA replication strands.

Nucleic Acid Structure and Function | DNA Replication and Repair |