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Agarose gel preparation

Agarose to weigh for a gel, and which percentage resolves your fragment.

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1% is 1 g in 100 mL.

TAE or TBE, as the gel is cast in.

bp

Checks the percentage suits it.

Agarose to weigh

1g

Into 100 mL of buffer, for a 1% gel.

What each percentage resolves

  • 0.5%1,00030,000 bp
  • 0.7%80012,000 bp
  • 1.0% — yours50010,000 bp
  • 1.2%4007,000 bp
  • 1.5%2003,000 bp
  • 2.0%502,000 bp

The bounds are where resolution starts to fail, not hard limits. A fragment just outside still runs; it stops being distinguishable from its neighbours.

Formulamass = percentage (w/v) × volume; 1% w/v = 10 g/L

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TBE resolves small fragments better and buffers longer; TAE is kinder to DNA you intend to extract from the gel, since borate inhibits several enzymes. Dissolve fully before pouring — undissolved grains scatter light and read as bands — and add stain once the gel has cooled below about 60 °C.

About this tool

Weigh the agarose for a gel of a given percentage and volume, and check that the percentage suits what you are trying to separate. The second half is the useful one: the working range of each percentage is a table nobody has to hand, and running a 500 bp product on a 0.7% gel costs an afternoon.

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Science last reviewed .