Southern blotting is a technique used to detect specific DNA sequences in a sample. It involves extracting DNA from a source, cutting it into fragments using restriction enzymes, separating the fragments by size through gel electrophoresis, and then transferring the fragments to a membrane and using a radioactive probe to detect sequences that hybridize. Southern blotting is used for gene discovery, mapping, and confirming that a known sequence has been incorporated into the genome of a genetically modified organism.

1. Southern Blotting
BY
SYEDA BATOOL ABBAS

2. What is Southern blotting?
 Purpose : It is used for DNA analysis for the
detection of specific DNA sequences in a DNA
sample.
Also known as DNA blotting .
Technique developed by Edwin Southern in
1975 in Edinburg university.
 Method named after its inventor.
 Specify the presence or absence of a
particular nucleotide
 Used in genetically modified organisms.

3. Principle
To Extract, purify and identify specific DNA sequences from
other cells.

4. METHOD
Step 1:
DNA is separated
from the source
and cut into many
small restriction
fragments by
digesting it with
restriction
enzymes.

5. METHOD
Step 2
The complex
mixture of
fragments is
subjected to gel
electrophoresis to
separate the
fragments according
to size.
Shortest at the top
longest at the
bottom.

6. Step 3:
Ethidium Bromide
intercalates
between the DNA
strands making it
visible.
DNA is taken from
the gel and
placed in the
nylon filter.

7. Step 4:
A radioactive
DNA probe is
added to the
complement
ary DNA
strands.

8. Step 5:
Excess probe is
washed away and
the probe bound
to the filter is
detected by
autoradiography,
which reveals the
DNA fragment to
which the probe
hybridized.

9. Overview

10. USES OF THE TECHNIQUE
 Southern blots are used in gene discovery and mapping,
evolution and development studies, diagnostics and
forensics.
In regards to genetically modified organisms, Southern
blotting is used as a definitive test to ensure that a
particular section of DNA of known genetic sequence has
been successfully incorporated into the genome of the host
organism.

11. References
1) http://highered.mheducation.com/sites/0072556781/student_view0/chapter14/animation_
quiz_5.html
2) http://www.bio.davidson.edu/genomics/method/Southernblot.html
3) https://askabiologist.asu.edu/southern-blotting

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13. Thankyou !