Page 1 of 1: genetics AIIMS mcq

lissa · Credits: 772 My Scrapbook

for measurement of long DNA sequences following is used a.chromosome walking b.nitch c.RFLP d.SSLP ASHISH GUPTA says dat answer is RFLP.i wanna know why not A?has anybody answer to this NO REFERENCES GIVEN IN THE BUK.do you kno anythn abt SSLP?I CONSULTED harper & lippincott!

lissa · Credits: 772 My Scrapbook

neuron03 · Credits: 3504 My Scrapbook

correct answer is - Chromosome walking.

it is a method for identifying and sequencing long parts of a DNA strand, e.g., a chromosome. as the traditional chain termination method does not allow long DNA strands to be sequenced, this method works by dividing the long sequence into several consecutive short ones. the basic technique is as follows:

1. a primer that matches the begining of the DNA to sequence is used to synthesize a short DNA strand complementary to the unknown sequence, starting with the primer (cf PCR).
2. the new short DNA strand is sequenced using the chain termination method.
3. the end of the sequenced strand is used as a primer for the next part of the long DNA sequence.

hence, 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 related but different method with the same purpose which has become more popular for large-scale sequencing (esp in the Human Genome Project) is "shotgun sequencing".

ref: NMS genetics and online textbook of mol biol.

neuron03 · Credits: 3504 My Scrapbook

some more information from wikipedia-

the process described as chromosome walking should appropriately called primer walking where the main aim is to sequence the genome. Chromosome walking is employed when we know the sequence but don't have a clone of a gene. (eg. suppose the gene for a disease may be located near a RFLP on DNA) .

lissa · Credits: 772 My Scrapbook

but i m not satisfied with it
i have to know why RFLP is wrong too.aakhir ek mcq ka sawal hai baba!!!!!!!!!!!!!

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