Chromosome Walking

Question 1

positional cloning

Answer 1

wen a gene is cloned based on its mapped position along a chromosomes

Question 2

what is one method of positional cloning?

Answer 2

chromosome walking

Question 3

what is chromosome walking?

Answer 3

a mapped gene or molecular marker provides a starting point from which to molecularly walk toward a gene of interest via overlapping clones

Question 4

how is chromosome walking initiated?

Answer 4

it requires using a gene close to the gene of interest. A small piece of DNA from the neighboring gene is inserted into another vector called sub cloning

Question 5

what does sub cloning do?

Answer 5

a sub cloned piece of DNA is at the end of the insert, so when it is used as a probe, it identifies the second clone closer to the desired gene.

Question 6

what is library screening?

Answer 6

using a subcloned gene as a probe, where the clone is exposed to embers of a cosmid library

Question 7

how do you know you’re not walking in the wrong direction?

Answer 7

when starting at a neighboring gene, markers on the other side of this gene are also identified

Question 8

how do researchers know when they have reached the gene of interest?

Answer 8

in the case of a disease causing gene, researchers would use chromosome walking in an affected and unaffected individual