What is genetic engineering?

Genetic engineering along with other terms such as: genetic modification, genetic manipulation, or biogenetic technology in general, are used to describe the process by which specific genetic information is isolated and then transferred to a new organism to attain a certain quality or trait. There are a few main steps in the process of genetic engineering:

1. Identification of the gene of interest
2. Isolation of that gene
3. Insertion into plasmids
4. Multiplication of plasmids using bacteria
5. Transferring into desired organism
6. Integration of gene into recipient genome

With these steps bioengineers are able to use traits and features from one organism and give that trait or feature to another organism. This can be used to create cops with better yield, more resistance to insects, or even enhance the taste of the product. This technology can also be used in animals and humans in order to increase growth, cure diseases, or determine the sex of an offspring. Applications will be discussed in more detail later in this page.

There are some other important terms that need defining:

• Plasmid - A small circle of DNA found inside bacteria, used in the transfer of genes between bacteria
• transgene/Transgenic organisms - An organism that contains foreign genes
• Recombinant microbes - A microbe that contains foreign genes
• rDNA (recombinant DNA) - DNA that is formed from genetic material from a number of different sources
• Vectors - An organism or virus that can be used to transfer genetic material
• Restriction Enzymes - 'Molecular scissors', cut DNA strands in very specific places
• Cloning - replicating DNA or parts of DNA in order to use in protein synthesis
• Knock out organism - An organism where a specific gene/trait has been removed
• Knock in organism - An organism where a specific gene/trait has been added

There are several important people and discoveries that have enabled this growth:

Frederick Griffith - The Transforming Principle (1928)

• He discovered that bacterium had the possibility to exchange genetic material between themselves

Joshua Lederderg - Discovery of Plasmids (1946)

• Built on the ideas of Frederick Griffith
  • The way that bacteria exchange genes is using plasmids
  • Also found that virus can be used to inject and transfer DNA by a process called transduction
  • His ideas are fundamental in today's biotechnologies
• Won the Noble Prize in 1958 for his work

Hamilton Smith - Recombination and Site-Specific Restriction Enzymes (1970)

• Discovered that there are enzymes that cut DNA at very specific locations
  • Is used when trying to isolate a specific gene

Genetic engineering is a complicated process with a variety of steps. To illustrate and describe this process, we will work it through with a common example. One of the very first commercial uses of genetic engineer to produce a medical product is the production of human insulin using bacteria. It was the first to be put onto the market as a commercial product in 1982. Since then we have found many other ways use this technology.

Identification of the gene of interest

When scientists are looking to modify an organism genetically they must first identify what trait they are trying to modify in that organism. This desired trait could be a huge range of things depending on what organism is being modified. In our example the trait we want to be expressed in bacteria is the production of human insulin. To accomplish this the gene for insulin production must be first identified in our DNA.

Removal of gene and Multiplication of plasmids using bacteria

For the most part the removal of a gene from an organism is going to be done by a restrictive enzyme. A diagrams with a series of steps is the best show this process:

While this diagram has a lot of detail, it clearly shows the simple process by which a desired gene is transferred from one set of DNA to another.

1. The first plasmid or DNA, containing the desired gene, is cut using restriction enzymes. These restriction enzymes work like biological scissors, cutting the DNA in a very specific location. There are different restriction enzymes which will cut the DNA in different places. Scientists will modify a restriction enzyme to cut in a specific place.
   • In our example restriction enzymes were used to cut the insulin gene out of a human DNA strand.
2. Once it has been cut the other DNA can be discarded. The same restriction enzymes are then used to cut a plasmid from a bacteria cell. One of the most common cells used is E. Coli, and this is also the case in the production of Insulin. When a restriction enzyme cuts a strand of DNA it leaves a 'sticky end'. For more on this click here.
   • It is very important that the same restriction enzymes are used in both cuts. This is to ensure that, in our example, the insulin gene cut from our DNA will be able to fit into the plasmid.
3. Because it was the same enzyme that cut both strands the removed piece will fit directly into the other. Also the sticky ends allows ligase to re-bond these sections of DNA to the rest of the chain allowing them to become a fully functional part of the bacterial DNA.
4. Because of the fast reproduction cycle of bacteria, and the fact that its DNA is copied exactly every time it splits, the insulin code will be produced again and again.
5. The bacteria then start to produce the protein that the scientists coded it for. Using this method scientists were able to create 'mini insulin factories' out of E. Coli bacteria.

CRISPR - Clustered Regularly-Interspaced Short Palindromic Repeats

• CRISPR is a very new technology that allows scientist to be able to cut and repair DNA inside the desired host cell. This removes much of the process being described above and below. It is being hailed as one of the most important breakthroughs in the genetic engineering world. Many say it will change the way that genetics is done.
• For more information click here.

Transferring into desired organism And Integration of gene into recipient genome

• Electroporation
  • Using electric current to create small pores in the surface of the plant cell
  • This allows the desired genes to enter the cell 'on their own', through these pores
• Microinjection
  • Using a nano-syringe the DNA is injected directly into the plant cell
  • This is very time consuming and not very cost effective
• Liposome transfer
  • A spherical bi-lipid layer containing the desired gene attaches itself to the cell wall
  • The gene is then released into the cell

Biological - Vector gene transfer

• Agrobacterium Tumefaciens
  • A bacteria found in the soil that is used to host, multiply and then insert into the plant cell
  • Tumefaciens contains plasmids which have sections of DNA that can be easily manipulated
  • The desired gene is added to this bacteria, using restriction enzymes (described above)
  • Plant cells are treated with this bacterium. It invades the plant cell and inserts the DNA into the cells
    • Is therefor often called the natural genetic engineer

Gene Transfer in Animal Cells

Many of the same techniques are used when transferring new genetic information into animal cells

• Electroporation - This is very similar to plants, but it is more frequently used because animals cells do not have a cells wall, making this more effective in animal cells
• Gene Gun - very similar to plants
• Microinjection - very similar, sometimes the entire nucleus is transferred from one cell to another. Often used in the process of cloning
• Retroviral transfer - A virus is rendered defective, making it harmless. Then different DNA is added to the virus. Scientists then infect the cells with this virus. The virus then inserts its DNA into the cell.
• Engineering Embryonic stem cells - ES (embryonic stem cells) are removed when the animal fetus is only around eight cells. They are then maintained in culture. The new genes are added in this stage. The cells are then grown and are put back into the womb of the mother.

The main, overarching questions are:

1. Are we 'playing God' when we edit our genes?
2. God placed us in dominion over this earth. How does this play out in our uses of genetic engineering?
3. What are the distinctions between genetic engineering in plants, animals, or humans?

There are many other questions that come from this. (These questions are in relation to genetic engineering in humans)

1. What is our role in the development of DNA and genes?
2. Are we to predetermine the sex of a child?
3. Can we support these technologies even when the use of embryonic cells is become more prolific?
4. What sort of genes can we control?
   • Looks? Size? Strength? a.k.a Can we create a 'super-human'?
5. How will the future generations be affected by modifications in our genes?
   • Does this impact what sort of things we should be doing today?
6. What sort of diseases should be cured?
   • All of them? What about Down syndrome and other similar, non life threatening diseases?
   • If these things are identified in the child in the womb. Do we correct it as soon as possible?
   • What about purely physical disabilities detected in the womb? If, someday, the technologies exist, to fix these disabilities what is the most ethical/christian approach?
   • What do the above say about our view if the sanctity of all human life?
7. To what extent can we treat our children in the womb?

In order develop thoughts about these, and other, questions there are some guidelines that we should follow as christians. Michael McKenzie wrote an article titled, 'The Christian and Genetic Engineering' on the website 'Christian Research Institute'. McKenzie explains it very clearly, so I decided to quote her article verbatim. (For the full article click here)

1. Humans are both finite and sinful. We lack both the wisdom and purity necessary to decide matters of human “perfection.” It is, therefore, immoral to use such genetic technologies as human eugenics and human cloning. Thus a theology of health and disease (as opposed to “enhancement”) must be developed in accordance with sound biblical guidelines.

2. Human life, with the image of God and an accompanying ensoulment, begins at conception. We are also responsible for how we treat the most helpless in our society (i.e., what Jesus called “the least of these”). Thus there should be important limitations for prenatal testing, and genetic diagnostics must not be used to pressure parents into abortion.

3. God’s Word is clear that humankind — both corporately and individually — is fully responsible for actions the Bible calls “sin.” Consequently, Christians should resist attempts to convert all antisocial behaviors into genetic diseases that nullify personal responsibility and accountability.

4. Humans are God’s highest creation and are commanded to be good stewards of the earth and its resources. Thus we have a mandate to engage in genetic research and therapy, when it is directed toward the healing end of medicine.

There is also another article that I found to be comprehensive and helpful, click here. And I am sure that there are many others online as well.

A summary of the big picture of genetic engineering using Insulin as an example:

• https://www.youtube.com/watch?v=H7FdzpE2GIE

Bozeman describes some important history related to genetics, and also some helpful background information:

• https://www.youtube.com/watch?v=qoERVSWKmGk

A helpful description of plasmids and their uses:

• https://www.youtube.com/watch?v=GNMJBMtKKWU

Click here for a helpful animation on the electrophoresis and DNA/RNA probes.