How to isolate specific dna fragment?

[ZEGSUS]

How to isolate specific dna fragment?

[canalon]

PCR?
Cloning?
Reverse-transcription?
Depends on what you know about your specific fragment, and what you want to do with it. You will need to be more precise if you want a good answer.

[ZEGSUS]

Well I want to isolate specific dna fragment from linear dna which have many dna fragments.I know his code.

[canalon]

Do a PCR and then separate with gel electrophoresis the fragment of the expected size.
You will have your fragment only, and if you want to clone it, it is easy to add all sorts of modifiers on your primers for further analysis (addition of tags to the protein or the RNA for purification, restriction sites for cloning and expression,...)

[ZEGSUS]

And can i use primers for pcr without electrophoresis ?

[greatmicrobiologist]

you have to use primers for the specific sequence required in PCR. Then for the separation of your required fragment form the bulk of fragments you have to go for electrophoresis, i.e. purification.

[JackBean]

And can i use primers for pcr without electrophoresis ?

You must use primers for PCR, no matter, what you do with the reaction afterwards You can e.g. purify the amplicon by some spin columns or directly digest with RE and afterwards purify etc.

[merv]

you have to use primers for the specific sequence required in PCR. Then for the separation of your required fragment form

think you meant from not form

the bulk of fragments you have to go for electrophoresis, i.e. purification.

i think we both know that separation by electrophoresis is not the same as purification.