POLYTECHNIC SCHOOL OF ENGINEERING Gel Electrophoresis Pre-lab questions For what

Question

POLYTECHNIC SCHOOL OF ENGINEERING Gel Electrophoresis Pre-lab questions For what reason do scientists use gel electrophoresis? through the gel matrix during gel electrophoresis? to the negative pole? To the positive pole? 1. 2. What are the properties of molecules which aflect how they migrate 3. In general, what type of molecules would you predict to move closer 4. The agarose gel used in electrophoresis contains microscopic pores that act like a strainer. If you have a mixture of DNA fragments (all with the same charge), would you expect large or small DNA fragments to move faster? How could gel electrophoresis be utilized to determine the size of DNA fragments in an unknown sample? 5. 6. Why would you expect DNA fragments to migrate towards the po sitive pole/electrode on the agaro se gel during electrophoresis?

Explanation / Answer

1.

With the help of applying an electric current to the gel matrix, scientists can separate deoxyribonucleic acid (DNA), ribonucleic acid (RNA) or protein molecules. Once the seperation is done, a photo is taken of the gel which provides a picture of the separated molecular parts. This process is known as electrophoresis and helps us in better understanding and identification of molecular components of living things.

Forensics

In forensics, gel electrophoresis is mainly used to obtain DNA fingerprint of a criminal. Meaning that scientists can accurately tell whether two pieces of DNA, one found at a crime scene and one belonging to a suspect, are matches.

Molecular Biology

Gel electrophoresis is used in molecular biology on a regular basis. This process allows them to separate and organize DNA and RNA by size, hence making it easier to study them at the molecular level.

Genetics

Gel electrophoresis helps provide geneticists with a clearer picture of DNA, it also helps prepare DNA for cloning and genetic engineering purposes

Microbiology

Microbiology is centered around the study of organisms at tiniest levels, gel electrophoresis and is helpful in pulling information out about these organisms. Virology, a subset of microbiology, also uses the process to help diagnose different strains of viruses.

Biochemistry

Biochemists work with cellular components, particularly proteins and nucleic acids. These components may also be mapped out using gel electrophoresis.

2.

There is a number of factors that can affect the migration of nucleic acids:

Dimension of the gel pores (gel concentration),

Size of the DNA being electrophoresed,

The voltage used,

Ionic strength of the buffer,

Concentration of intercalating dye such as ethidium bromide if used during electrophoresis.

3. When we put an electrical current through: one of the ends becomes negative while the other positive, molecules that are negative in charge will move towards the positive charge, but only up to a certain point. That factor being their size.

4. There will be no movement

5. In order to calculate the sizes of bands in other lanes of the gel, we would first construct a standard curve like the one at the left from the migration of the DNA fragments in the 1 kb ladder. And plot the log 10(number of base pairs) for each fragment on the y-axis against the distance that each fragment migrated on the x-axis.

6. The DNA molecules which has a negative charge because of the phosphate groups in their sugar-phosphate backbone, hence they start moving through the matrix of the gel towards the positive pole

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