Re: How it is possible to transfer the gene from eukaryot to the prokaryot

Gene transfer from Eukaryote to prokaryote

The genetic material of the prokaryote and eukaryote being the same, 
there is difference in the synthetic machinery in terms of presence or 
absence of introns and other ribosomal units (70s in prokaryotes and 80s 
in eukaryotes). There are few minor differences in the genetic machinery 
but while cloning a gene from eukaryote to prokaryote there are few 
things which needs to be questioned:

Molecular cloning involves isolation of a gene or DNA fragment from 
another organism (foreign DNA) inserted into independently replicating 
cloning vector. 
The few steps are as follows: 
1. Extract total genomic DNA from cells containing target DNA
2. Use a restriction enzyme to cut the DNA into smaller fragments and to 
linearize the cloning vector.
3. Join the DNA fragments to the cloning vector to produce recombinant 
DNA molecules
4. Introduce the recombinant vector into a host cell.
5. Identify and isolate a strain containing the cloned target DNA.
In case of eukaryotic gene to be cloned in a prokaryote Ex. Large 
multigene prokaryotic operons and eukaryotic genes with introns can be 
inserted in:
1. Cosmid. ~40 kbp of insert DNA
2. Artificial chromosomes. ~ 100 to > 2,000 kbp of insert DNA. Ex. Yeast 
artificial chromosomes (YAC) 
Also to express eukaryotic genes in prokaryotic cells, the eukaryotic DNA 
needs to transcribe the DNA to mRNA and then translate it to protein. 
However, as eukaryotic DNA has introns, and since prokaryotes lack the 
machinery to splice them, the splicing of eukaryotic DNA must be done 
prior to adding the eukaryotic DNA into the host (as well, before placing 
the eukaryotic DNA into the prokaryote, a prokaryotic promoter region must be
added, if not already present on the vector). This spliced DNA is called 
complementary DNA.

Regards,
Devendra Dusane

Further reading:  http://www.answers.com/topic/complementary-dna 
http:
//www.science.siu.edu/microbiology/micr421/chapter4.html