2.  Biotechnology includes genetic engineering and other techniques that make use of natural biological systems to produce a product or to achieve an end desired by human beings.  Genetic engineering: is the use of technology to alter the genomes of viruses, bacteria, and other cells for medical or industrial purposes.  Genetic engineering has the capability of altering the genotypes of unicellular organisms as well as the genotypes of multicellular plants and animals, including ourselves.

3. R 1. 1. “relaxed” plasmid 2. 2. Supercoiled, 3. more supercoiled  Recombinant DNA (rDNA) contains DNA from two or more different sources.  To make rDNA, it often begins by selecting a vector, the means by which rDNA is introduced into a host cell.  One common type of vector is a plasmid.  Plasmids are small accessory rings of DNA from bacteria. The ring is not part of the bacterial chromosome and replicates on its own.  Plasmids were discovered by investigators studying the reproduction of the intestinal bacterium Escherichia coli (E. coli).

4.  Two enzymes are needed to introduce foreign DNA into vector DNA.  1. Restriction enzyme, cleaves the vector’s DNA  2. DNA ligase, seals foreign DNA into the opening created by the restriction enzyme.  Hundreds of restriction enzymes occur naturally in bacteria.  They are called restriction enzymes because they restrict the growth of viruses, but they also act as molecular scissors because each one cuts DNA at a specific cleavage site.

5.  For example, the restriction enzyme called EcoRI always cuts double-stranded DNA in this manner when it has this sequence of bases: GAATTC so this enzyme cleaves the sequence between the G and the A, this produces DNA restriction fragments.  The single-stranded, with complementary ends of the two DNA molecules are called “sticky ends” because they can bind a piece of foreign DNA by complementary base pairing.

6. Sticky ends facilitate the insertion of foreign DNA into vector DNA.  2. DNA ligase: the second enzyme needed for preparation of rDNA molecule, used to seal the foreign piece of DNA into the vector.  DNA splicing is now complete; an rDNA molecule has been prepared.

7.  Bacterial cells take up recombinant plasmids, especially if they are treated to make them more permeable.  Thereafter, if the inserted foreign gene is replicated and actively expressed, so it is possible to recover either the cloned gene or a protein product.  In order for gene expression to occur in a bacterium, the gene should not contain introns because bacteria don’t have introns. Example: Cloning of human Insulin gene in a bacterium

8. Today, bacteria, plants, and animals are genetically engineered to produce biotechnology products.  Organisms that have had a foreign gene inserted into them are called transgenic organisms. 1. From Bacteria;  When the foreign gene is inserted into bacterium, replicated and actively expressed, a large amount of protein product can be obtained. Biotechnology products produced by bacteria includes:  insulin, human growth hormone, and hepatitis B vaccine, are now on the market.

9. 2. From Plants Techniques have been developed to introduce foreign genes into plants to produce human proteins,  such as hormones, clotting factors, and antibodies, in their seeds.  One type of antibody made by corn can deliver radioisotopes to tumor cells, and  another made by soybeans can be used to treat genital herpes virus.

10. 3. From animals:  Gene pharming, the use of transgenic farm animals to produce pharmaceuticals.  Genes that code for therapeutic and diagnostic proteins are incorporated into the animal’s DNA, and the proteins appear in the animal’s milk.  There are plans to produce drugs for the treatment of cystic fibrosis, cancer, blood diseases, and other disorders.  for producing transgenic mammals: DNA containing the gene of interest is injected into donor eggs. Following in vitro fertilization, the zygotes are placed in host females where they develop. After female offspring mature, the product is secreted in their milk.