Multiple Choice
Restriction enzymes are proteins responsible for what?
15. Genomes and Genomics
Sequencing the Genome
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Dideoxy nucleotides (ddNTPs) are used in Sanger sequencing because they have what function?
A
ddNTPs add fluorescence to the DNA sequence
B
ddNTPs speed up DNA amplification
C
ddNTPs stop elongation once they are incorporated into a growing sequencing reaction
D
ddNTPs prevent stalling of DNA sequencing reactions
Verified step by step guidance1
Understand the role of dideoxy nucleotides (ddNTPs) in Sanger sequencing. They are crucial for terminating DNA strand elongation during the sequencing process.
Recognize that ddNTPs lack the 3'-hydroxyl group necessary for forming phosphodiester bonds with the next nucleotide, which is why they stop elongation.
Incorporate ddNTPs into the DNA synthesis reaction. When a ddNTP is added to the growing DNA strand, it prevents further addition of nucleotides, effectively terminating the strand.
Identify the purpose of using ddNTPs in sequencing: by terminating strands at different lengths, they allow for the determination of the DNA sequence when analyzed through gel electrophoresis or capillary electrophoresis.
Note that ddNTPs are often labeled with fluorescent tags, which help in detecting the terminated fragments during the sequencing process, but their primary function is to stop elongation.
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