6.3.5(Electrophoresis)

Describe the use of gel electrophoresis

• It is used to separate different sized fragments of DNA.

• It is accurate enough to separate fragments that are only one base different in length

Describe and explain how electrophoresis works

• It uses an agar gel plate covered by a buffer solution

• Electrodes are placed in each of the tank, so that when it is connected to a power supply, an electric current can pass through the gel. DNA has overall negative charge, due to its many phosphate groups and the fragments migrate towards the anode

• Fragments of DNA all have a similar surface charge, regardless of their size

Describe and explain how seperating proteins occurs during electrophoresis

• It is the same process as separating DNA fragments

• However, it involves a charged detergent

Explain why separating proteins in electrophoresis requires a charged detergent

• This is because proteins have a charge depending on their R group

• The charge depends on the pH and so the detergent is used during the separation of proteins to keep the pH constant

• This allows the proteins to fragment on the gel based on their molecular mass and not their charge

Explain how the technique of separating proteins is useful in electrophoresis

• It shows genotypes of individuals by separating polypeptide chains produced by different alleles

• It can be used to analyse types of haemoglobin proteins for diagnosis of conditions such as sickle cell anaemia