iGEM Thessaloniki - Agar Electrophoresis

In which direction does a segment of DNA move when an electric potential is applied to the agarose gel?

• Towards the descent

• Towards the rise

• It doesn't move

Answer explanation

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Why is ethidium bromide used?

• To increase the viscosity of the electrophoresis gel

• To move the DNA faster through the gel

• To visualize the electrophoresis results under a UV lamp

• None of the above

Answer explanation

IMPORTANT NOTE :

EtBr is a potent mutagen and moderately toxic after an acute exposure. EtBr can be absorbed through skin, so it is important to avoid any direct contact with the chemical. The powder form is considered an irritant to the upper respiratory tract, eyes, and skin.

How is the size of a DNA fragment estimated after electrophoresis?

• Spectrophotometrically, by measuring absorptions in a UV detector

• By comparing the distance traveled by DNA fragments to a scale of DNA "controls" of known molecular weight

• By sequencing the base pairs, after quantification by PCR

Answer explanation

Here's an example of a typical control DNA ladder.

How are the separated fragments visualized in agarose electrophoresis?

• As bands on the gel

• As spots on the gel

• As streaks on the gel

What is included in the agarose gel to estimate the size of unknown fragments?

• A DNA or RNA ladder

• A protein ladder

• A buffer solution

What can the intensity of the bands on the gel be used to estimate?

• The size of the fragments

• The amount of DNA or RNA in the sample

• The height of the voltage

In agarose electrophoresis, do smaller DNA or RNA fragments migrate farther through the gel than larger ones?

• True

• False

How does the use of different types of DNA or RNA stains affect the visualization of bands on the agarose gel?

• It does not affect visualization

• Some stains may cause DNA to appear brighter, while others may cause RNA to appear brighter

• Some stains may cause larger fragments to appear brighter, while others may cause smaller fragments to appear brighter

How does agarose electrophoresis differ from polyacrylamide gel electrophoresis (PAGE)?

• Agarose gels have larger pore sizes, allowing for separation of larger DNA or RNA fragments

• Polyacrylamide gels have larger pore sizes, allowing for separation of larger DNA or RNA fragments

• Polyacrylamide gels have higher resolution than agarose gels

Supercoiled DNA migrates faster than predicted in an agarose gel.

• True

• False

Answer explanation