Gene Sequencing

[B10Student]

I'm not sure how the use of a bacterial plasmid to clone and sequence a human gene contributes to understanding genetics. Can someon explain what "sequencing a human gene" is exactly?

Is it just finding specific squences that are the genes of interest? Do you use a nucleotide radioactive probe to complete this procedure? Thanks.

Also, how is transformation of a foreign DNA into a bacteria carried out? Can you use heat to shock the bacteria to have them take the DNA in? Does that count as being transformation? Thanks again.

[canalon]

sequencing is finding the the sequence/order of A[denosine], G[uanosine], C[ytosine] & T[hymidine] that makes up the DNA. Cloning it in bacterial plasmid allow faster copying because bacteria will make copying each fragment faster (think of each plasmid as a unique page that is fed in a photocopy machine, each fragment/page is fed in one photocopier very fast, OTOH if you have to make plenty of copies of the whole genome it is just like taking a heavy leather bound book and copying it without damage. Very slow). For the details you can start here:
http://en.wikipedia.org/wiki/Sequencing
or, of course, there:
http://www.biology-online.org/1/5_DNA.htm

Depending on what you are looking for (whole genome vs single gene) the use of a probe can be useful to detect which bacteria contains the plasmid that has your fragment of interest. The probe can be radioactive, but other system (biotinylation, Digoxygenine relying on immuno detection are available).

Transformation in the laboratory is carried out by Heat shock or electroporation (the latter is more efficient, but more costly in terms of equipment and cell preparation, but it is mor fun when it is failing). But many bacteria are even able to simply pick-up DNA in the environment. Not that the efficiency would be even close to useful in the lab though.

[tittu]

you use biolistics (gene gun), microinjections etc..