In order to understand genetic engineering some knowledge of the biological makeup of life on this planet must be considered. Organisms exist as two grades. The simplest are the prokaryotes, ordinary bacteria, blue-green bacteria, blue-green algae, viruses and so on. The other larger and more complex life forms, the eukaryotes, will be considered in a moment. First let us look at the prokaryotes.

All of these have their genetic material as rings of DNA, or RNA in some viruses. These tiny organisms seem to be economizing on their genetic material because many of these coding regions overlap. They possess special DNA sequences between genes for at least two purposes. Firstly, the control of gene function, such as the turning off of gene transcription by the products of the coded enzyme in operons, and for providing sequences recognized by transcription or replication enzymes; secondly, there are DNA sequences that incorporate the DNA between them into other strands of DNA. (Examples would be into a host bacterium, for a plasmid or a bacteriophage, or a host eukaryote cell for a virus.) There are bacteria that produce a few enzymes which actually snip or join DNA by recognizing specific sequences for snipping or joining between two nucleotides. By using these enzymes it is possible to determine the sequence of DNA lengths. This is done by digesting them sequentially with enzymes which recognize the different sequences. Then each mixture of shorter resultant sequences is analyzed with other enzymes.

This is a lengthy process requiring millions of tries. But then Yilanè patience is infinite and we have had millions of years to develop the process. In order to recognize particular sequences, radioactive DNA or RNA messengers are attached specifically with base complementation along their length. Afterwards, special enzymes are used to remove a specific length and insert it into another organism’s DNA ring.

This is the way that bacterial DNA rings are modified: Firstly by the use of plasmids, natural bacterial ‘sex’ sequences; secondly, by phages, viruses that naturally attack bacteria; thirdly by using cosmids, artificial DNA circles with special joining sequences, any of which can be tailored to include new or modified genes, so that the modified bacteria can make new proteins.

So it can be seen that it is relatively easy to change the protein chemistry of bacteria, simple eukaryotes such as yeast, and to reprogram other eukaryotic cells in a similar simple manner.