Which one of the molecular processes utilize 2', 3' Dideoxy-ribonucleoside triphosphates?
Which one of the molecular processes utilize 2', 3' Dideoxy-ribonucleoside triphosphates?
Select an option to attempt
Correct Answer: Option C
Explanation
2',3'-Dideoxynucleoside triphosphates (ddNTPs) — application:Structure: ddNTPs lack both the 2'-OH and 3'-OH groups on the ribose sugar.Function: When incorporated into a growing DNA chain by DNA polymerase, the ABSENCE of the 3'-OH means the next nucleotide CANNOT be added (no free 3'-OH for phosphodiester bond formation). This terminates chain elongation.Application: Sanger sequencing (chain termination method / sequencing by synthesis):1. A template is copied by DNA polymerase in the presence of dNTPs (normal) + a small amount of ddNTPs (chain terminators labelled with fluorescent dyes).2. Termination occurs randomly at each position where a specific base is incorporated.3. The resulting fragments of all lengths are separated and detected to read the sequence.Distractors:• DNA synthesis for primers: primers use regular dNTPs.• Okazaki fragment formation: also uses regular dNTPs.• Transcript elongation: uses NTPs (ribonucleotides), not ddNTPs.Answer: DNA sequencing by synthesis (Option 3).