Hello Ahmed,

You do not need to add extra nucleotides to your oligos to clone the PCR product in pGEM-T vector. Reason for this is, you will be cloning your gene of interest using T/A cloning technique. You have two options here. A. PCR amplify your gene of interest using Taq DNA polymerase, which will add a single "A" to 3' of the PCR product. B. PCR amplify your gene of interest using a high fidelity polymerase (such as Pfu), purify PCR product and add 3' "A" using terminal transferase (ddATP as substrate) or Klenow exo- fragment (dATP as substrate). 

The complementary "T" overhangs of pGEM-T vector and "A" overhangs of the PCR product hybridize and result in recombinant plasmid containing your gene of interest.

For pGEM T easy vector, You can use simple primer for cloning and you must!! to use Taq DNA polymerase for gene amplification. Becuase Taq is able to add "A" to 3' overhang of PCR product. PCR product which have A overhang can be cloned directly to pGEM T easy.

Good luck

Hi Ahmed,

Primer3 is a great tool to pick your primers from a particular sequence. Regarding the pGEM-T vector I agree with Syed, you can insert the PCR fragment via T-A cloning. However you have to be aware, that your fragment can be inserted in both directions. If you want to add a restriction site to your primers you just need to add the sequence of the particular enzyme to the 5' end of your primers and additional random 4 nucleotides to give the restriction enzyme a place to start. Once you have performed your PCR you digest your PCR product and your vector with the same restriction enzymes (separate reactions). After that you perform a ligation reaction to join the PCR fragment with the vector. 

Best Simone

 Thanks very much to all of you, I really appreciate your comments.

i often use Snapgene to design primers. I think that is the best way