Question

What is the first step in the Southern blot technique?

• A. Denaturation of DNA on the gel for hybridization with specific probe
• B. Production of a group of genetically identical cells
• C. Digestion of DNA by restriction enzyme
• D. Isolation of DNA from a nucleated cell such as the one from the scene of crime

Answer 1

Answer: (D)

Isolation of DNA from a nucleated cell such as the one from the scene of crime

A Southern blot is a method to detect specific DNA sequence in a given DNA samples. The first step in a Southern blot is to prepare the DNA mixture by breaking it into small fragments using a restriction enzyme. The mixture of DNA fragments is then separated according to size by way of a technique called gel electrophoresis. Following separation, the double-stranded pieces of DNA are denatured, or separated, into single strands within the gel. Next, the DNA is transferred from the gel onto a blotting membrane. This step is what gives the technique the name Southern blotting.