Genetic Engineering

Ancient Greek mythology talked about chimeras.

Chimeras are a combination of different organisms.

The chimera was a fire-breathing monster with the body and the head of a lion, the head of a goat and the tail of a serpent.

With the use of biotechnology, modern scientists are creating chimeras in the lab.

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Early Study of BioengineeringFarmers have used selective breeding for thousands of years to create new versions of plants and animals.

These new crops and animals were created through sexual reproduction and the passing of positive traits from parent to offspring.

Early Study of BioengineeringOnce the DNA molecule was identified, studied and became known as the universal code for genetic information, scientists began to realize that they could transfer gene information from one type of organism and insert it into another type of organism.

In this picture corn plants have been a gene that acts as an insecticide to prevent bugs from eating the corn.

Some people are concerned that the insecticide gene will kill not only the harmful bugs, but the insects that pollinate the corn plants.

How safe are bioengineered products?

Some scientists and consumer activists are concerned that “superweeds” (plants that are not able to be killed with herbicides) or plants that contain poisonous chemicals will become part of our food supply and cause harm to humans.

Other scientists are claiming that they have found a way to feed the starving people in underdeveloped countries with plants that are genetically altered with vitamins and minerals.

The Genetics of Viruses and Bacteria

Viruses are referred to as “obligate

intracellular parasites”

In order to understand the mechanism of bioengineering one has to study viruses and bacteria.

Lytic cycle of viral reproduction

Bacteria can protect themselves from invading viral particles

Scientists discovered restriction enzymes in bacteria living in the hot springs of geysers. These restriction enzymes protect bacteria from invading viral DNA.

Scientists have learned a way to use these enzymes to cut DNA into small pieces.

Tools of Biotechnology

Restriction enzymesRestriction enzymes “cut” DNA at specific nucleotide sequences. There are many different types of restriction enzymes and scientists use these enzymes to cut DNA into small pieces.

Restriction enzymes

restriction enzymes

DNA LigaseDNA ligase will “seal” the cut ends of DNA together.

In this way a foreign piece of DNA can be inserted into another piece of DNA.

Insertion of DNA into a plasmidBacteria are often used in genetic engineering.

In addition to the circular bacterial chromosome, bacteria often contain plasmids (small, extranuclear pieces of DNA)

Plasmids often carry antibiotic resistance genes.

A gene of interest can be inserted into a bacterial plasmid wit the use of restriction enzymes and DNA ligase.

Recombinant DNA has been formed and can be inserted into a host cell.

Insertion of the human insulin gene into a bacterial plasmid

One way that scientists use bacterial plasmids is by inserting the human gene for insulin into the bacterial plasmid.

In this way, the bacteria “read” the gene for insulin and make massive amounts of insulin for people that are diabetics.

In the diagram the term, clone, refers to identical copies of the bacteria with the insulin gene.

Insertion of gene into plant cellsOnce again the question remains…. How safe is the corn plant to eat and what effect will it have on other insects that may be useful to the plant or to other plants?

Additionally, what could happen if the gene were to be combined with a normal corn plant gene through the process of pollination?

Will other plants then become deadly to insects?

Separating genes through gel electrophoresis

Once the DNA has been cut by restriction enzymes, the fragments can be separated by electrophoresis.

Small fragments are carried farther by an electrical current through a gel material. Larger size fragments travel slower.

Polymerase Chain Reaction

In the diagram, a “gene of interest” has been isolated through electrophoresis and copies are made.

Similar to a xerox machine, a PCR chamber uses available DNA nucleotides and DNA polymerase to make multiple copies of the “gene of interest”.

Insertion of gene by way of gene gun

Gene gun

Insertion of gene using pro-nuclear injection

Pro-nuclear injection is used most often with animal cells.

The “gene of interest” is inserted into the cell of a host animal.

The host animal will contain the “gene of interest”.

How safe is genetically modified food?