Chromosome walking is a technique used to analyze large regions of DNA by identifying overlapping clones. It involves selecting a starting clone, subcloning fragments from the ends, and using those fragments to screen a genomic library and identify neighboring clones with overlapping sequences. This process is repeated to "walk" along the chromosome. Chromosome walking was developed in the 1980s and is useful for finding mutations associated with genetic diseases and detecting single nucleotide polymorphisms, though it has limitations with repetitive sequences.

1. CHROMOSOME WALKING
SIVASANGARI SHANMUGAM

3. CHROMOSOME WALKING
INTRODUCTION :
A technique which produces set of overlapping DNA clones for
studying segments of DNA larger than can be cloned individually.
A method for the analysis of larger region of DNA, in which a
each end of a large single cloned DNA fragment is separately to
screen recombinant DNA genome library for other clones
containing neighbouring sequences.
Chromosome walking was developed by Welcome Bender, Pierre
spierer & David S.Hogness in the early 1980s.

4. CHROMOSOME WALKING
The technique of chromosome walking involves the
following steps ;
1. From genomic library select a clone of interest (identified by
probe) & sub clone a small fragment from one end of the clone.
2. The sub cloned fragment of the selected clone may be hybridized
with other clones in the library & a second clone hybridizing
with the sub clone of the first clone is identified due to presence
of overlapping sequence.

5. 3. The end of the second clone is then sub cloned & used for
hybridization with other clone to identify a third clone having
overlapping region with the sub cloned end of the second clone
4. Third clone identified as above is also sub cloned & hybridized
with clones in the same manner & the procedure may be
continued.
5. Restriction map of each selected clone may be prepared &
compared to know the regions of overlapping so that
identification of new overlapping restriction sites will amount
to walking along the chromosome or along a long chromosome
segments.

8. DISADVANTAGES
1. Limitation in the speed of chromosome walking due to small
size of the fragments.
2. If the markers were too far away, it simply was not a viable
option.
3. The difficulty of walking through the repeated sequence that
are scattered through the genes.

9. APPLICATION
1. Used to find mutation and analysis of genetically
transmitted disease
2. Used to detect the single nucleotide
polymorphism in different organisms.

10. REFERENCE
1. http://feedforbiotech.blogspot.com/2011/03/chromosome-
walking.html
2. http://www.genevoguebiotech.com/2012/09/chromosome-
walking.html
3. http://www.wisegeek.com/what-is-chromosome-walking.html
4. http://wiki.answers.com/Q/Applications_of_chromosome_walki
ng_and_jumping#ref1

11. THANK YOU