Multiple Choice
The final step in a Sanger DNA sequencing reaction is to run the DNA fragments on a gel. What purpose does this serve?
18. Biotechnology
Dideoxy Sequencing
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Dideoxy sequencing is also known as chain termination sequencing because:
A
The dideoxy nucleotide prevents further synthesis of DNA due to the lack of a free 5' carbon.
B
The dideoxy nucleotide prevents further synthesis of DNA due to the lack of a free 3' OH.
C
The dideoxy nucleotide prevents further synthesis of DNA due to the lack of a nitrogen-containing base.
D
Chain termination is the same as sequencing by synthesis.
E
None of the above are correct.
Verified step by step guidance1
Understand the concept of dideoxy sequencing, also known as Sanger sequencing, which is a method used to determine the nucleotide sequence of DNA.
Recognize that dideoxy nucleotides (ddNTPs) are crucial in this method because they lack a hydroxyl group at the 3' position, which is necessary for forming a phosphodiester bond with the next nucleotide.
Identify that the absence of the 3' OH group in ddNTPs prevents the addition of further nucleotides, effectively terminating the DNA chain elongation.
Clarify that the statement 'The dideoxy nucleotide prevents further synthesis of DNA due to the lack of a free 3' OH' is correct because it explains the mechanism of chain termination in dideoxy sequencing.
Review the other options provided in the problem to ensure understanding of why they are incorrect, focusing on the specific role of the 3' OH group in DNA synthesis.
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Dideoxy Sequencing practice set
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