Gel electrophoresis problems

[miyukiaura]

Hey, does anyone know where you can find some tricky gel electrophoresis practice problems?

Thanks

[Erutepa]

Hey, does anyone know where you can find some tricky gel electrophoresis practice problems?

Thanks

A great way to get some challenging questions on different topics is by using a book like ATAR notes topic tests/checkpoints/biozone if you can get your hands on them. Otherwise you can pull up past exams and scan them for elecrophoresis questions that were answered poorly (as indication that they were challenging). From a quick look over some past exams It seems most gel electrophoresis questions have been answered fairly easily - the only poorly answered electroscopes question I could find was one from last years exam with only 9% getting the full marks. The question is included in the spoiler below for you to have a go at if you wanted.

Question

The Genomics Health Futures Mission will run a $32 million trial, starting in 2019, to screen over 10 000 couples who are in early pregnancy or who are planning to have a baby. Using a blood test, individuals will be screened for 500 severe or deadly recessive gene mutations. Couples will be told they have a genetic mutation if both individuals in the couple carry the same mutation. The trial may lead to a population-wide carrier screening program. The researchers will evaluate cost effectiveness, psychological impact, ethics and barriers to screening. It is anticipated that future tests will be free of charge.

The blood sample from an individual will provide researchers with only a small amount of DNA. Polymerase chain reaction (PCR) will be used to amplify the DNA.Describe what happens in each of the three stages of PCR. The stages must be given in the order in which they occur.

Once the DNA has been amplifi ed, it can be loaded into a well of an agarose gel.         
Discuss three factors that affect the migration of DNA fragments through the agarose gel during gel electrophoresis. 3 marks

Examiner's report (answer)

Suitable responses for factors affecting the migration of DNA fragments through the agarose gel during gel electrophoresis included three of the following:
 • the size of the molecules,as the larger molecule will move more slowly
 • the charge of the molecule,as the negative charge means that DNA moves towards the positive electrode
 • the length of time the voltage is applied,as there may not be enough time for the DNA to migrate through the gel
 • the concentration of the agarose,as denser agarose results in the molecules moving more slowly.
Students needed to discuss each factor rather than just list them.

Hopefully this is useful and sorry i couldn't provide more questions

[miyukiaura]

Thanks for finding that question  I've been doing the ATAR notes topic tests but I'll have a go at that question.