Science Buddies: "Ask an Expert"

Hi, I really need help doing a molecular cloning experiment.

I am a Ph.D student doing a rotation in a lab that does molecular cloning all the time but I am super confused with all the explanations I am getting.
Basically, I need to make a DNA construct consisting of 3 different DNA sequences.
2 of the DNA sequences we need to isolate from a mice tissue and the third DNA seq. is in a vector.
Then, I will do the Gibson-Assembly PCR experiment to put that those 3 inserts into a plasmid.

Now, my confusion is in the primer designing part. Do we need to design the primers to isolate the DNA sequences from the tissue or are the primers used in the Gibson-Assembly run?
Another question is, how does one isolate those DNA sequences?

The Science Buddies Ask the Experts forum is for students in grades K-12 who are doing hands-on science projects. There are other sites on the web where your questions would be more appropriate and likely to get useful responses.

Thank you.
Madeline
Moderator