Gibson Vector Insert Molar Ratio and DNA Amount Tool
Use the existing plasmid DNA-amounts panel to relate vector mass, insert length and a chosen insert-to-vector molar ratio. The reference opens pUC19 with a declared single-insert example. It does not automatically prepare a multi-insert Gibson reaction or infer stock volumes for fragments whose concentrations have not been supplied.
Versioned pUC19 sequence plus user-editable example inputs: 50 ng vector, 720 bp insert and a 3:1 insert-to-vector ratio. The native DNA-amounts tool lives in the plasmid workspace and is reused here; these inputs do not assert an optimised assembly protocol.
Count molecules before combining fragments
A vector mass can look similar to an insert mass while representing very different molecule counts. The length and molar-mass relationship explains why assembly protocols discuss molar ratios. The reference begins from a known pUC19 sequence so the vector identity is explicit. The illustrative insert length supplies only amount-planning information; it is not a complete sequence-defined insert.
Changing the insert length while retaining its intended molecule ratio changes the required mass. Changing the vector mass scales the preparation demand. Neither edit validates the fragment ends or their overlaps. Keep the amount calculation and the sequence-assembly check as separate parts of the record, connected by the actual fragment identities rather than a shared generic label.
Move from a single insert to a complete assembly design
For multiple inserts, each fragment needs its own length, concentration and intended contribution. A total nanogram budget alone does not define the stoichiometry. A short fragment can contribute many more molecules than a long one, and a low-concentration stock can consume most of the reaction volume. Those constraints should be visible before a mixture is prepared.
The plasmid workspace also contains sequence-level assembly tools. Exact overlap compatibility describes a possible product under the model; it is not evidence that the reaction produced that construct. Preserve the distinction between a designed sequence, a simulated product and an experimentally confirmed clone. Subsequent restriction analysis or sequencing provides evidence that amount arithmetic cannot supply.
Equations and variables
Amount from DNA mass
n = m/MW
- n
- Amount of DNA molecules (mol)
- m
- DNA mass (g)
- MW
- Molar mass of the stated DNA sequence and topology (g/mol)
Insert-to-vector molar ratio
r = ninsert/nvector; minsert ≈ mvector × r × Linsert/Lvector
- r
- Chosen molecule ratio
- Linsert, Lvector
- Fragment lengths (bp)
- minsert, mvector
- Corresponding DNA masses (ng)
Scope and limitations
- The current native panel provides single-insert amount planning, not an automatic multi-fragment stock-volume recipe.
- Length-ratio mass calculations approximate the relationship through comparable DNA composition; sequence-derived molar mass and terminal chemistry can matter when greater precision is needed.
- A chosen molar ratio does not establish correct overlaps, complete linearisation, fragment purity or assembly efficiency.
Sources and provenance
- GenBank pUC19 record L09137.2Existing source notice: NCBI public domain
Versioned sequence and SHA-256 are pinned in the shipped example.
- Gibson et al.: enzymatic assembly of DNA moleculesCited method; no article data reproduced
- Plasmid methods and DNA-amount assumptionsExisting project methods and source notices
Technical questions
Why can equal masses give unequal numbers of fragments?
A longer DNA molecule has a greater molar mass, so the same nanogram mass contains fewer molecules. Assembly ratios concern molecule amounts rather than equal weights. Keep the vector and insert lengths with the calculation so the chosen ratio can be reconstructed.
Does this page calculate every volume in a multi-insert reaction?
No. The native panel shown here plans DNA amounts and a single-insert ratio. A multi-fragment recipe also needs each stock concentration, reaction capacity and an explicit strategy for relative amounts. Those inputs must not be fabricated from fragment names or lengths.
Does a three-to-one ratio guarantee assembly?
No. It is an editable example input, not an optimum established for your fragments. Overlap sequence, fragment quality, unwanted products and reaction conditions can dominate performance. Inspect the actual sequence design and retain the manufacturer or laboratory protocol used for the experiment.
Connected workflows
- Type IIS restriction-site inspection
Compare a different sequence-defined assembly mechanism.
- Virtual restriction digest and fragment sizes
Plan a sequence-based digest to inspect a resulting construct.
- GenBank and FASTA plasmid mapping
Review the actual vector sequence and annotations.
- Gibson Assembly Overlap and Primer Annealing Designer
Inspect the homology overlaps of a sequence-level Gibson assembly.