Question

Describe each of the 5 steps of a Southern Blot:

(1) Cut
(2) Gel Electrophoresis
(3) Filter Paper
(4) Probe
(5) X-ray

Answer 1

The Southern blot is a molecular biology technique involving the cutting of DNA, gel electrophoresis to separate the DNA fragments, their transfer to a membrane, probe hybridization, and finally, detection through X-ray or autoradiography to identify specific DNA sequences. The correct option is

Step-by-step explanation:

The Southern blot is a method used in molecular biology to detect the presence of a specific DNA sequence within a DNA sample. The procedure can be summarized in five main steps:

1. Cut: The genomic DNA is digested with restriction enzymes to cut it into smaller fragments.
2. Gel Electrophoresis: The resulting DNA fragments are separated according to size through agarose gel electrophoresis.
3. Transfer to Filter Paper: The DNA fragments are then transferred from the gel to a nylon or nitrocellulose membrane via capillary action.
4. Probe Hybridization: A single-stranded DNA probe, labeled with a radioactive or fluorescent marker, is added to the membrane to hybridize with the complementary DNA sequence of interest.
5. X-ray or autoradiography: The membrane is then exposed to an X-ray film or a different detection method to visualize the bound probe, indicating the presence of the target DNA sequence.

This methodology is powerful for genetic analysis, permitting scientists to identify specific sequences in complex DNA samples, estimate their abundance, and even recover certain DNA fragments for further study.