Help me while u having fun :) 
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 Help me while u having fun :)

Hi guys. I need a little help on a question
regarding the Molecular biology.

Here is the Question ----->

"Mu" is a generalized transducing phage(i.e. similar to P1).
a derivative of MU was constructed that appears as follows.

        Mu                                      Mu
        left                                    right
        end     lacZ            bla(ampR)       end
             |           |
             ^           ^
           no promoter   promoter

It's called Mu-lac and has the following properties:

properties1: Mu is a phage that can intergrate( ie. form a lysogen)
        at random sites in the genome of the host cell, E.coli. this property
        is determined by the sequences found in both ends of Mu. Thus, Mu-lac
        can also intergrate at random sites.
properties2: Following infectionss with Mu-lac phage, cell w/ Mu-lac integrate
        into their genome can selected by virtus of being virtue of being
        ampcillin resistant due to th presence of a bla gene w/ its own pro-
properties3: The lacZ gene is intact and lacks only a promoter. Thus,B-galacto-
        sidase activity can only be expressed if Mu-lac insertion occurs
        downstream from an active promoter.

Questions are:

1: Devise a selection to isolate an E.coli cell that has a Mu-lac insertion
in araB gene. (u may begin w/ a cell containing any combination of lactose
mutations that u wish) It's will not b possible to do step 4 as a counter-
selection: u will have to do complementation. ASsume that u have a collection
of cells w/ F' factors containing the entire arabinose operon, including one
that r araA-. araB-. araC-, and araD-.

2: From araB- cells, devise a seleciton to isolate an e.coli cell that
expresses lacZ under control of the arabinose promoter, Pbad. (no needd do
step 3 and 4 in this selection)

3: Not alls araB- mutants isolated by the steps in question#1 will express lacZ
under the control of the arabinose promotor, Pbad. What is the main reason for this and what fraction of cells isolated in question#1 would u predict to be
in question#2

4: Give an argument Y the containing mutants of concern in question#1 would
in fact not have grown effectively in the selection u proposed in ur answer
to question#2..


Any responses will be greatly appreciated,

have fun, guys....  :)



HumanHunter  :->

>                          \/\/\/\/\              
>                          /       /        
>                         (. (.  )        
>                          (      ]      
>                         /____  /                
>                          \     |                
>                          /-----\                
>                        / /     /  \            
>                      / \/       \/  \          
>                    / / /           \  \
>                  ((()  /__________\ (/\)))  
>                         /         \
>                         |    /\    \
>                         ----| |----
>                         |__ |  \__ \
>                        {____|   {___}
>                 =======================/
>                    (o)           (o)  

is ME ME and ME...........

Sun, 04 May 1997 07:42:51 GMT
 [ 1 post ] 

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