Part One ~ DNA Cloning/Recombinant DNA/Genetic Engineering

Gene Cloning with Bacterial Plasmids


Describe it- Genetic engineering involves the insertion of new genetic material at an unspecified location in the host genome. This is accomplished by isolating and copying the genetic material of interest, generating a construct containing all the genetic elements for correct expression, and then inserting this construct into the host organism.

Analyze it- First, the gene to be inserted into the genetically modified organism must be chosen and isolated. Once isolated, the gene is inserted into a bacterial plasmid. The gene to be inserted into the genetically modified organism must be combined with other genetic elements in order for it to work properly. Stressing the bacteria using a heat shock or an electric shock, can make the cell membrane permeable to DNA that may then incorporate into their genome. If a cell has been successfully transformed with the DNA it will also contain the marker gene. By growing the cells in the presence of an antibiotic or chemical that selects the cells expressing that gene it is possible to separate the affected cells from the non-affected.

Apply it- Genetic engineering has applications in medicine, research, industry and agriculture and can be used on a wide range of plants, animals and micro organism. In medicine genetic engineering has been used to mass-produce insulin, human growth hormones, follistim , human albumin, antibodies, vaccines and many other drugs. Vaccination generally involves injecting weak live, killed or inactivated forms of viruses or their toxins into the person being immunized. Industrial applications involving genetically engineered bacteria being investigated involve making the bacteria perform tasks outside their natural cycle, such as cleaning up oil spills, carbon and other toxic waste. One of the best-known and controversial applications of genetic engineering is the creation of genetically modified food. GM food is used so farmers can produce the maximum amount of their crop as possible and in turn make more profit and feed more people.

Synthesize it- Genetic Engineering could be compared to the lysogenic cycle of viruses. Like genetic engineering, a virus will incorporate its DNA into a host cell and thus pass the viruses DNA onto the daughter cells when the host cell divides. When certain conditions exist the DNA from the viruses will then exit the host cells DNA and enter the lysic cycle and reproduce.

Argue it- Genetic Engineering can be very beneficial to humans through various ways. It could feed more people, save life's, and help prevent diseases from spreading. I also believe that it could go to far and become a bad thing. If we start cloning humans are picking out certain genes that we want in our children then I believe that is morally wrong and we should let nature take its course.


Nucleic Acid Hybridization


Describe it- A technique in which single-stranded nucleic acids, DNA or RNA, are allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences.

Analyze it- The two strands of a DNA molecule are denatured by heating to about 212°F. At this temperature, the complementary base pairs that hold the double helix strands together are disrupted and the helix rapidly dissociates into two single strands. The DNA denaturation is reversible by keeping the two single stands of DNA for a prolonged period at 149°F. This process is called DNA hybridization. Similar hybridization reactions can occur between any single stranded nucleic acid chain: DNA/DNA, RNA/RNA, DNA/RNA. If an RNA transcript is introduced during the renaturation process, the RNA competes with the coding DNA strand and forms double-stranded DNA/RNA hybrid molecule .

Apply it- Nucleic acid hybridization techniques offer an insight on characterization of the predominant, yet unculturable populations in nature, the role of the environment in gene expression, and the extent of gene exchange among communities in nature.

Synthesize it- Imagine a article of clothing that is ripped or torn in a certain area. To fix this, the clothing must be sewn back together by taking each individual strands and putting them back into a certain a pattern. Like Nucleic Acid Hybridization a DNA strand is denatured, the clothing being torn, and then put back together with either another DNA or RNA strand. The strands being put back together is like our article of clothing being sewn back together so it can appear and work as it was meant too.

Argue it- Nucleic Acid Hybridization is an excellent way to recombine DNA or RNA strands to express different genes. Hybridization gives humans idea how genes are being expressed under certain environmental conditions which could lead to research that we could benefit from.


Genomic Library

external image 10_23_genomic_library.jpg

Describe it- A genomic library is a collection of host bacteria that contain a plasmid with a gene of interest. The population of bacteria holds different kinds of genes that would represent the genome of an organism.

Analyze it- A genomic library consists of many important parts. First you need a plasmid from a bacteria cell. Then you need a DNA molecule that contains the gene of interest. Using restriction enzymes, the plasmid and DNA molecules are cut up in a way where "sticky sides" or matching base pairs cause the plasmid and DNA to connect. All you need now is a host bacteria to replicate it's new genes.

Apply it- You now have a population of bacteria cells with all kinds of different genes from the DNA molecule. The bacteria will replicate and transcribe these genes into proteins. Let's pretend one of the genes creates insulin. Now we have insulin-making bacteria for diabetics, that way we don't have to use insulin from animals that could have allergenic side effects.

Synthesize it- A genomic library is, as the name states, like a library. A library contains many different kinds of books and you can choose a book that interests you. A genomic library is the same. It contains many bacteria with different genes and you can pick out the one that will create the type of protein you are interested in.

Argue it- I think it's great that we have genomic libraries. We can pick out certain bacteria that make proteins from a gene of interest and make cures for diseases and such. I see no reason to not use this method.


Polymerase Chain Reaction (PCR)

Describe it- PCR is a method used to amplify a copy of a DNA sequence. This can be used to create hundreds to thousands copies of the sequence.

Analyze it- A DNA molecule is first heated to remove hydrogen bonds and separate it into two single stranded DNA molecules. Cooling of the DNA allows DNA polymerase to bond directly to the ends of the desired sequence. Making the environment room temperature will allow the polymerase to replicate the sequence and the rest of the molecule. Repeating this process multiple times will eventually result in just the desired sequence to be copied, as shown in the video above.

Apply it- PCR creates thousands of the same DNA sequence which is required for methods such as hybridization and DNA cloning.
Synthesize it- PCR is kind of like a man-made DNA replication process, except for we are only replicating specific sequences and we are cloning DNA at a much higher rate.

Argue it- I don't think there is to much controversy over PCR, but if there is I would have to argue for it. I don't think there are to many problems with this process besides possible mutations that could mess up stuff. Even still, I think this is a big step in genetic engineering.