Science In Context Genomes Genes And Cloning Biology Essay

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Monosanto needed to insert two genes into the soybean genome. The one from the primrose codes for the enzyme that helps to convert the oleic acid to linoleic acid, and linoleic acid to the alphalinoleic acid. The second gene from the fungus could have helped in acting as a promoter sequence which helps to increase the level of expression of the EPA. On the other hand, the in case of the insect resistance, only the Bt gene needs to be inserted as this protoxin is directly converted into the active form when it enters the membranes of the insect's intestinal cells.


Since the DNA in eukaryotes never leaves the nucleus, it is fairly difficult to isolate particular genes from the DNA. However, the information of the DNA in the nucleus is transcribed onto the messenger RNA (mRNA) which undergoes splicing that removes the non-coding sequences of the genes - the introns. This splicing gives rise to the mature mRNA which is then passed out of the nucleus and is more easily accessible to be copied and used to isolate the required genes.

Although RNA can be extracted from the cytoplasm of the cell, it would not only contain mRNA, but also ribosomal RNA (rRNA) and transfer RNA tRNA). mRNA is separated from rRNA and tRNA through gel electrophoresis. It is then incubated with reverse transcriptase to produces a strand of DNA known as a complementary DNA copy (cDNA). This essentially has a base sequence that corresponds to that of the original mRNA. The mRNA strand is then destroyed, and the DNA polymerase synthesises the complementary strand that results in the double stranded DNA helix. In this way, we now have the required gene copied onto the cDNA. This is then inserted into the plant using vector plasmids.

Question 1 (c)

Using the soil bacterium Agrobacterium tumifaciens as a vector is probably the most effective way of inserting genes into plants. This is mainly because the bacterium contains a tumour-inducing plasmid (Ti plasmid) that can be modified to allow insertion of foreign genes into the plant cell genome. The plasmid is a small self replicating circle of DNA found in the some bacteria and is extra to the chromosomal DNA. The Ti-Plasmid is characterized by a transfer DNA (T-DNA) region that will become incorporated into the chromosomes of the host plant, thus any gene that is inserted into the T-DNA region will be inserted into the host plant. The Ti-plasmid is cut in the T-DNA region using restriction endonuclease, producing sticky ends. The fragments from the donor DNA containing the wanted genes are then mixed with the plasmid DNA where the sticky ends of both are joined. The plasmid vector is then reinserted into the bacterial cell which allows it to multiply. The modified bacterium can now be used to infect the plant cells, where the Ti-plasmid is transferred into the plant chromosomes. Since the Ti-plasmid in the bacterium is quite big, it would be somewhat easier to construct an artificial Ti-plasmid and use a helper vector such as E. coli to transfer it to the plant. The advantage of artificial plasmids is that it can be constructed without the tumour-inducing genes, the virulence region and without the genes coding for opine synthesis and catabolism.

Question 1 (d)

Heart disease is one of the major causes of death, brought about mainly by the consumption of various inappropriate foods in the diet. Consumption of fish can reduce the risks of heart disease, since their oils are rich in omega-3-fatty acids which play and important part in reducing heart failure. This puts a substantial amount of pressure on fish stock, and the production of GM soybean can help alleviate the pressure, whilst making omega-3 fatty acids more readily available for consumption. So, this could be a good way of reducing the incidence of heart problems caused by the inappropriate diets.

Question 2 (a)

The book was published in 1998 far before the Human Genome Project was complete. The value of 100,000 genes was an estimate of what scientists were expecting. In actual fact the findings and data suggested a count in the region of 30,000-35,000 genes which is way below what scientists had anticipated.

Question 2 (b)

Genetic pollution is the dispersion of genes from a genetically modified crop to a natural non modified crop by for example cross-pollination.

Question 2 (c)

Cloning is the process by which identical copies of genes, molecules, oranisms are made through genetic engineering. A cloned animal is one whereby the animal is reproduced from a single cell that has been taken from the parent animal. The cloned animal will essentially have the same exact DNA and would thus be genetically as well as physically identical to the parent animal.

Chimerism is the presence of two or more genetically distinct types of cell in one single organism. Chimeric animals are generally a result of using stemm cells, whereby a new gene can be introduced into the cell. The successfully modified stem cells are then injected into the embryo and become part of itsnormal development. The resulting animal know as a chimera is a mixture of two genetically different cells some derived from the normal stem cells and other derived from the modified stem cells.

Transgenesis is the process by which organisms have been genetically altered using genetic engineering techniques. Such organisms are generally referred to as being transgenic. the process involves the alteration of the DNA of an organism by the insertion of genes from an other organism with the aim of expressing a new trait that previously did not exist in the organism. The probable main reason for the genetic engineering of animals is ther use as pharmaceutical factories where by they are being used to produce protein such as the human coagulation factor, as well as being used as models for research of specific diseases.

Question 2 (d)

The risk factors associated with human cloning are likely to be similar to those encountered in human cloning. Human cloning is bound ot have similar ineffieciencies as those observed with the case of Dolly, where nuclear material was transferred from and adult sheep to an ennucleated egg and then implanted into a surrogate mother, In this case, out of a total of 277 attempts to clone a sheep, only one succeeded. Further more, Dolly developed complication and abnormalities and had to be put down only half way through what would be the normal life span of a sheep. The inefficiencies and risks associated with the process, are most likely to be the major cause attributed to the high cost of the process. Human cloning is likely to encounter similar risks and complications and probably results in similar outcomes. This could possibly make the procedure less attractive to prospective parents.

Question 2 (e)

Genetic determinism is the view that phenotypes are caused by genotypes, and although this might be true to some extent or other, one must also bare in mind that most traits are determined by more than one gene. Hundreds of genes may play a role in the complex traits such as intelligence and personality. Also to be noted is the fact that some genes produce more than one phenotype, thus making it more difficult to for example enhance intelligence without causing other adverse effects such as aggression or anxiety. Environment and development also play an inportant role in determining some traits, and for example, a genetic predisposition for alcholism will not develop into alcoholism if the individual never drinks. Thus, although a trait could be strongly genetically determined, it could be too complex to modify leading to the idea that the enhancing certain traits seems to be slightly far fethched.

Question 3 (a)

Question 3 (b)

Here is the final list of questions:

1) What is the specific aim of the Genetic Modification (i.e. health benefits, disease eradication etc.) and will it cause undue suffering to the "host"? 

2) How does the work that you propose bring benefits to the potential recipients and what are the possible harmful effects of it to them?   

3) Can conventional therapies or medications achieve the same or similar effect as the GM animal pharmaceutical?   

4) What is the predicted success rate of the product?    

5)  How many animals would be used in order to develop the GM animal and how many may be harmed in the process?

6) How will GM animals affect native animals and its ecosystem if they find their way into the natural environment?

7) What information do you intend to make publicly available (i.e. not just available to and restricted to medical practitioners) about how your pharmaceutical was produced and tested?   

8) Do you intend to retain intellectual copyright and monopoly production of this technology or make it available for anybody to use?

Minority Opinion; Question 3 is not agreed with by two of the group as they believe whether the same results can be achieved is irrelevant to the development of a new technology.