Question

You would like to see if the gene that you are studying in mouse has a homolog in humans. To do this you decide to do a Southern blot. You believe the gene sequence will be not be highly conserved. Therefore, you would like to select conditions to hybridize your probe with low stringency to find as many candidates as possible.  Which condition (in term of slat concentration) will you use?

Select one:

a. At Lower Salt Concentration

b. At Higher Salt Concentration

Answer 1

Ans) A higher salt concentration would be appropriate for low stringency hybridization.So, option B is correct.

Explanation:

There are 2 kinds of washing conditions which are used to remove non specific hybrids in Blotting techniques:

1)High stringency washing: It utilizes high temperature and low salt conditions. It allows hybridization of identical sequences or highly conserved sequences.

2) Low stringency washing :It utilizes low temperature and high salt conditions. It allows hybridization of  highly diverged sequences. In such situation, high salt minimizes the repulsion between sugar and phosphate backbone; low temperature maximizes rate of hybridization. These conditions allow non specific hybrids formation.

So, according to the condition given in the question,gene sequence is not highly conserved , so,low stringency washing would be appropriate and for that low temperature and high salt conditions would be required.Therefore, option B is correct.