Dideoxynucleotides

Definition

Dideoxynucleotides are modified nucleotides lacking a 3' hydroxyl group, which prevents the addition of further nucleotides during DNA synthesis. They are essential components in Sanger sequencing for terminating DNA strand elongation at specific bases.

5 Must Know Facts For Your Next Test

1. Dideoxynucleotides are used in Sanger sequencing to create fragments of varying lengths for DNA analysis.
2. They lack a 3' hydroxyl group, which is crucial for the formation of phosphodiester bonds in DNA strands.
3. Each type of dideoxynucleotide (ddATP, ddTTP, ddCTP, and ddGTP) corresponds to one of the four DNA bases.
4. In whole-genome sequencing, they help determine the precise order of nucleotides by terminating synthesis at specific points.
5. Fluorescently labeled dideoxynucleotides allow automated sequencers to detect and read the sequence of DNA fragments.

Review Questions

Related terms

Sanger Sequencing: A method of DNA sequencing that uses dideoxynucleotides to terminate chain elongation and produce fragments for analysis.

Phosphodiester Bond: A bond formed between the phosphate group of one nucleotide and the hydroxyl group of another nucleotide.

Fluorescent Labeling: The attachment of fluorescent dyes to molecules such as dideoxynucleotides to enable detection during sequencing.