U3A1: 4D gel electrophoresis

Question 1

purpose of gel electrophoresis

Answer 1

measures the size of DNA fragments in comparison to a standard ladder that represents molecular size.

Question 2

explain process of gel electrophoresis

Answer 2

• agarose gel immersed in buffer solution.
• DNA samples are placed in wells at one end of the gel with a micropipette, along with a standard ladder.
• electric current passed through the gel using a negative electrode at the wells and a positive electrode opposite the wells.
• smaller DNA fragments move faster through the gel.
• after a few hours, the current is switched off and the DNA fragments settle into bands.
• gel is stained with fluorescent dye, allowing the DNA bands to be visualised under UV lamp.

Question 3

4 variables that may affect distance

Answer 3

• time
• voltage (strength of current)
• buffer concentration (concentration of ions carrying electric current)
• gel composition (agarose concentration, density)