Page 1 of 1: chromosome walking

nadu · Credits: 17768 My Scrapbook

what is chromosome walking?
what is its significance?

RxPG_Team · Credits: 19657328 My Scrapbook My Reading List 5 Books

Chromosome walking is a method in genetics for identifying and sequencing long parts of a DNA strand, e.g., a chromosome. As long DNA strands cannot be sequenced, this method works by dividing the long sequence into several short ones.

Basically, chromosome walking works as follows:

A primer that matches the beginning of the DNA to sequence is used to synthesize a short DNA strand complementray to the unknown sequence, starting with the primer (see PCR).
The new short DNA strand is sequenced.
The end of the sequenced strand is used as a primer for the next part of the long DNA sequence.
That way, the short part of the long DNA that is sequenced keeps "walking" along the sequence. The method can be used to sequence entire chromosomes (thus, chromosome walking). A different method with the same purpose which becomes more popular for large-scale sequencing (e.g., the Human Genome Project) is shotgun sequencing.

draditithegreat · Credits: 1248020 My Scrapbook

i m still unable to understand.. plz help...

captainprasun · Credits: 1661 My Scrapbook

in plain words...

it is a technique...to identify long strnads of DNA

normally..in PCR. or othermethods of DNA amplification endonuclease can identify(cut) only small dna segment.....but if the dna segment is long..then then this is used....

HMMM example..
if dna is A...............B.............C.................D

then as this is long sequence..instead of one endonuclease..4 enzymes are use..which reads the signal as..A.....( part B) also....then B....(part C) also...and so on till D and thus when we make the whole sequence..it is like walking so it is called as Chromosome walking...
its confusing..so...it is a technique to idnetify long strnads of DNA

guest · Credits: 79379 My Scrapbook My Reading List 262569 Books

Nice explanations! let us put this in other words:

Whenever we need to sequence a DNA we have follow certain gel electrophoresis methods. No method can sequence more than 1500 base pairs (bp). Usually only 750 -1000 bp can be sequenced by automated systems. Now to sequence larger DNA we have various methods, chromosome walking is one of them. Here we need to know some part of the long DNA to be sequenced. This part is used for making primer (primer is a sequence that is complementary to this known sequence with certain other properties). In automated system, this primer is used for sequencing say next 1000 bp. Actually there are dideoxynucleotides that terminate the lengthening of primer and help in sequencing. Another post would be needed to explain sequencing. But let us assume 1000 bp are sequenced by our primer. The last 15-20 bp of this known sequence can now be used as new primer. Then next 1000 bp are read, and so on... The figure below uses the word probe instead of primer. This is called chromosome walking. If it is still not clear, do question again..

draditithegreat · Credits: 1248020 My Scrapbook

hjorq · Credits: 2435 My Scrapbook

Excellent explanation...
Can anyone shed light on shotgun approach too.. harper is a bit confusing.

guest · Credits: 79379 My Scrapbook My Reading List 262569 Books

Please read this

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If it does not help then do write back!!

hjorq · Credits: 2435 My Scrapbook

Thanks chand.

cma · Credits: 1011 My Scrapbook My Reading List 3 Books

can anybody explain the similrities n diff brtween chromosomal walkin and RFLP??

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