Restriction Enzymes & Gel Electrophoresis

Question 1

What is a Restriction Enzyme (a.k.a. Restriction Endonucleases)?

Answer 1

• Restriction enzymes are enzymes used to cut up DNA.
• They cut DNA in a staggered format meaning fragments are produced where one strand of the DNA extends beyond the complementary strand.
• The unpaired extension of the cut strand of DNA is called a sticky end.

Question 2

Restriction Sites

Answer 2

Restriction sites are specific regions in nucleotides cut by restriction enzymes in the DNA.

Question 3

What is Gel Electrophoresis?

Answer 3

Gel electrophoresis is a procedure that separates restriction fragments.

Question 4

What is the Gel Electrophoresis procedure like?

Answer 4

• In this procedure, DNA fragments of different lengths are separated as they diffuse through a gelatinous material under the influence of an electric field.
• Since DNA is negatively charged (because of the attached phosphate groups), the DNA fragments move toward the positive electrode.
• Short DNA fragments migrate further through the gel than longer and heavier ones.

Question 5

What are RFLPs?

Answer 5

RFLPs (Restriction Fragment Length Polymorphisms), is just another term to refer to restriction fragments, which are essentially DNA fragments.

Question 6

What is Gel Electrophoresis used for?

Answer 6

Gel Electrophoresis is often sed to compare DNA fragments of closely related species in an effort to determine evolutionary relationships.