Gel Electrophoresis Concepts and Techniques

Gel electrophoresis is a technique used to separate DNA fragments by size and shape. In this process, genetically engineered plasmids are mixed with glycerol and dyes, allowing them to sink into gel wells. When an electrical current is applied, negatively charged DNA fragments migrate towards the positive electrode. The migration speed is influenced by the DNA's size and shape. Plasmids can form different shapes, affecting gel results. After electrophoresis, the gel is exposed to UV light to visualize DNA bands, stained with ethidium bromide. A DNA ladder helps determine fragment sizes, and control lanes verify recombinant plasmid presence.

What is the purpose of using a viscous liquid in gel electrophoresis?

• To make the gel more transparent

• To increase the speed of DNA migration

• To change the color of the gel

• To help DNA samples sink into the gel wells

Which dyes are used to track the progress of DNA fragments in gel electrophoresis?

• Safranin and malachite green

• Methylene blue and crystal violet

• Eosin and hematoxylin

• Bromophenol blue and orange G

What charge do DNA fragments have that causes them to migrate through the gel?

• Positive

• Neutral

• Negative

• Variable

Which factor does NOT affect the migration speed of DNA through agarose gel?

• Electrical current applied

• Size of the DNA fragment

• Shape of the DNA fragment

• Color of the DNA fragment

Why can plasmids of identical size result in multiple bands on an agarose gel?

• Due to different weights

• Due to different shapes

• Due to different charges

• Due to different colors

What is used to visualize DNA samples after gel electrophoresis is completed?

• Infrared light

• Visible light

• Ultraviolet light

• X-ray light

What role does ethidium bromide play in gel electrophoresis?

• It acts as a buffer

• It speeds up DNA migration

• It stains DNA for visualization

• It changes the DNA charge

What is the purpose of a DNA ladder in gel electrophoresis?

• To separate DNA fragments by charge

• To determine the sizes of DNA fragments

• To change the gel's color

• To increase the gel's viscosity

What do control lanes in gel electrophoresis help confirm?

• The viscosity of the gel

• The speed of DNA migration

• The presence of recombinant plasmids

• The color of the gel

How do uncut and cut plasmids differ in gel electrophoresis?

• They migrate at different rates

• They change color

• They migrate at the same rate

• They do not migrate