How and Why are Organisms Genetically Modified? Year 9 Scholars project 2019, Charles Anson
What is meant by the term “Genetically Modified Organism” (GMO)?
An organism is a biological term to describe a ‘living thing.’ It could be a plant, animal, human, bacteria or virus. To modify something, means to change and genetics are the study of human characteristics. To add to this, genes are a set of instructions found in the DNA in the nucleus (control center) of all cells. This instruction helps to make the protein (we are all made from protein) that forms our body and helps us survive. This helps determine our characteristics, for example, our blood group or eye color. Although our genes mostly control our physical features, environment has an impact. If somebody should genetically be tall, but they don’t get the right diet they will not end up being tall.
This means that a genetically modified organism, is a plant, animal, bacteria or virus that’s genes have been swapped to produce a productive organism that is going to help humans in the future. Scientists in a laboratory, manipulate the genetic material of the two organisms to change their future characteristics. How and why they do this, I will to explain later.
DNA and Chromosomes
As mentioned earlier, DNA is a chemical that is stored the nucleus of our cells. The nucleus is effectively the brain of our cells, and the DNA is the set of instructions that tell amino acids to group together and make the protein. DNA is made from 4 chemical bases called adenine, cytosine, guanine and thymine, but for short, A, C, G, T. Base A is always paired with Base T, and it is the same for bases G and T. Each pair makes one rung of the DNA, double helix structure. The four letters can be arranged into groups of 3, resulting into 64 different possibilities. The 3-letter arrangement, for example ATG, stands for an amino acid. These come from food and are absorbed into the blood and carried into our cells. Amino acids make protein (body substance).
Each DNA forms itself into long strands called chromosomes. Each nucleus contains 46 chromosomes, arranged into pairs, making 23 pairs. Syndromes such as Down’s syndrome occur when a person has one extra chromosome but because genetic science is evolving, we can now see if someone may have the disorder before they are born. Chromosomes often form into an X-shape. The 46 chromosomes in each nucleus account for a full set of human genes, so there are almost 30,000 human genes in every cell in our body. Some cells, such as red blood cells, do not have a nucleus and therefore do not have genes. This is because the red blood cell is not genetic and is the same structure for every single human. In short, a gene is a functioning part of DNA, as parts of DNA are making what is known as ‘junk DNA’ which scientists do not really know the function of just yet. A chromosome is just a long strand of DNA containing lots of genes.
Enzymes Detail Study
Let’s start with restriction enzymes. As mentioned before, these are the scissors of genetic engineering. I am now going to write in more detail about how they work. They are also known as endonucleases. They scan and look for what is known as a ‘blunt end’ in the DNA sequence. It usually looks for a sequence of between 4 and 6 nucleotides. A nucleotide is one adenine string for example. A blunt end could therefore look something like ATGC TACG.
Once it finds the ‘recognition’ it wants to find, it stops and makes incisions. It makes two cuts in opposite directions, so it cuts the sugar-phosphate backbone of the DNA double-helix. When the enzyme makes its cut, the scientists are looking for a sticky end, rather than a blunt end. A sticky end is where the DNA sequence finishes with a single stranded nucleotide whereas a blunt end ends with a regular base pairing. The DNA is ‘sticky’ because it wants to become part of a DNA sequence again, whereas blunt ends don’t. A blunt end produces lower biological yield.
How does Genetic Engineering Work?
Before I start to write about genetic engineering, I want to establish that genetic modification and cloning are different things. When an organism is cloned, the exact copy of the same organism is produced, and the genes are just swapped between the same organism, no genes are modified. Whereas genetic modification, produces a new organism that nobody has seen before, as the genes are swapped and modified between different species.
What is a Transgenic Organism?
A transgenic organism is the official name for an organism whose genetic material has been modified. Transgenic organisms can pass on their genetic material to create more organisms that have been genetically modified.
How are Transgenic Organisms Modified?
Modifying transgenic organisms involves identifying the characteristic wanted, selecting the gene, getting it ready and inserting it into a vector (bacteria or virus). A vector is something used to transfer the DNA into a bacterium cell. After that, the bacterium duplicates to produce lots of cells with the gene that has been modified.
To achieve this stage, restriction enzymes are needed. Restriction enzymes recognise specific sequences of DNA and cut the DNA at those points. They are effectively the scissors in the operation. The other enzyme used is called the ligase enzyme. This is like glue and joins the inserted DNA to the vector. The different pieces of DNA stuck together are known as recombinant DNA.
Example 1-Insulin
Insulin is a hormone produced in the pancreas which regulates the amount of glucose(sugar) there is in the blood. A lack of glucose in the blood leads to Type 1 Diabetes. Therefore, Type 1 Diabetics must inject themselves with insulin. Genetic modification can help produce insulin so we can help Type 1 Diabetics. This is how it works:
A restriction enzyme is used to cut open the human insulin gene and the same restriction enzyme is used to get the vector DNA. The restriction enzyme looks for the specific point at which it wants to cut the DNA. The benefit of using a restriction enzyme is that it leaves a ‘sticky end’, which helps the human gene attach easily to the vector DNA. The vector DNA and the human gene are then mixed together with ligase enzymes. These enzymes join the two pieces of DNA together to produce recombinant DNA (the vector DNA and the human gene mixed). The recombinant DNA is then inserted into other cells, like bacterium cells. The cells now use the human insulin DNA to use the correct set of instructions to make the correct protein. In this case, insulin is produced. The bacteria then duplicate to form lots of cells with insulin. They are grown in a fermenter. This helps Type 1 Diabetes sufferers massively. The bacteria are now a transgenic organism. This process follows the 5 steps highlighted earlier: selecting the human DNA, cutting the human DNA and vector DNA, mixing them, inserting them into bacteria, and then multiplying.
Once the scientists have cut the desired gene using the restriction enzyme, they can now know which part of the vector DNA to cut from. This is so that they can get a complimentary DNA-base pairing. Once they have cut both the desired gene and the vector DNA, they need to use the ligase enzyme to stick them together.
Enzymes Detail Study
Let’s start with restriction enzymes. As mentioned before, these are the scissors of genetic engineering. I am now going to write in more detail about how they work. They are also known as endonucleases. They scan and look for what is known as a ‘blunt end’ in the DNA sequence. It usually looks for a sequence of between 4 and 6 nucleotides. A nucleotide is one adenine string for example. A blunt end could therefore look something like ATGC TACG.
Once it finds the ‘recognition’ it wants to find, it stops and makes incisions. It makes two cuts in opposite directions, so it cuts the sugar-phosphate backbone of the DNA double-helix. When the enzyme makes its cut, the scientists are looking for a sticky end, rather than a blunt end. A sticky end is where the DNA sequence finishes with a single stranded nucleotide whereas a blunt end ends with a regular base pairing. The DNA is ‘sticky’ because it wants to become part of a DNA sequence again, whereas blunt ends don’t. A blunt end produces lower biological yield.
Ligase Enzymes
Using ligase enzymes, or DNA ligation, is a huge part of the process of genetic engineering by sticking the two pieces of DNA together. They use ATP (an organic chemical to provide energy in human body functions) as an energy source, they catalyze the reaction between the phosphate group on one end of the DNA strand and the hydroxyl group on another end of the DNA strand. This produces the sugar phosphate backbone of a DNA structure.
Vectors
Vectors are not actually enzymes but have just as an important role in modification. A vector is the vehicle in genetic engineering. It is used to transfer DNA into a cell. There are two types: plasmids and viruses.
Plasmids: Small, circular molecules of DNA that can be transferred between bacteria.
Viruses: Insert DNA into the organisms they infect.
The vector is responsible for inserting the DNA into a bacterium so that they can be grown and duplicated with the new gene.
Cloning
Although cloning is not technically classed as genetic modification, they are very similar, so I will briefly mention what cloning is.
Cloning is just as it sounds, duplicating an animal/plant which has desirable characteristics, so it can be mass produced, which is along very similar lines to genetic modification. In plants, the stem is planted into damp compost. This is called a cutting. Plant hormones are then added to encourage the roots to grow. This method is so simple, most gardeners can even attempt it.
It can also be done ‘in vitro’, or IV, the same thing as you might have heard during pregnancy. All it means is ‘in glass’, so the plants are cloned in glass. To do this, a tissue sample must be shaved off the plant before being placed into sterile agar jelly, which contains plant hormones. Samples then develop into tiny plantlets. Finally, you would put them into the damp compost.
With mammals, you would want to clone for example, a chicken which produces lots of eggs, because they would produce a higher biological yield. The first mammal to be cloned was Dolly the sheep who was ‘born’ in 1996 and died in 2003. The following diagram shows you how it is done.
The cloned animal is identical because it has used a diploid nucleus (double the number of chromosomes) that is the same as its ‘foster’ parent. Genetic modification is where genes are mixed to create a new more resistant organism whereas cloning is copying a successful organism in order to breed more.
Why are Organisms Genetically Modified?
There are economic, commercial and philanthropic incentives for genetically modifying organisms. The main idea is to produce a food that has an advantage to the customer by either health or price, that wouldn’t have come about by allowing nature to do its work. This generally means that GM foods are cheaper and more sustainable and produce a higher yield. A yield is a word used to describe how much of a product is good, for example, the milk yield was high, this would mean that the milk is very good.
GMO’s are also being produced because scientists believe that they are more resistant towards insects and increased use of herbicide. Herbicide use has gone up 25% recently and if GM crops are more resistant to this, it would be great for farmers. Scientists can do this by inserting the gene for toxin production from a bacterium, into the food plant to make it more resistant to herbicides. This also would be a green light in terms of being environmentally friendly as pesticide use is damaging for the environment.
GM food would also be more resistant to natural disease that would kill off other crops. This would keep prices low and yields high. They would do this by the same way, inserting an infection-resistant gene into the normal food crop.
This biggest idea and the idea that made GMO’s invented in the first place was because they are more sustainable and can feed our ever-growing population, they stay on the shelves longer and are sold at a lower price.
Aside from preventing disease in foods that are there already, scientists are also producing new foods such as ‘golden rice’. Golden rice has higher beta carotene levels, in other words, vitamin A, because they spotted a shortage of the vitamin in humans. As humans eat a lot of rice, it was a good ‘invention’.
Away from foods, in medicine, genetic modification is very prominent because as I mentioned earlier, insulin is being mass-produced using genetic modification, so Type 1 Diabetics glucose levels stay normal.
Problems with Genetic Modification
Despite genetic modification being the future of food for our population, huge problems remain, and it is not the finished article.
Moral Ethics
Lots of religions, such as Hindus and Muslims, claim that genetic modification is ‘playing God’ by producing new foods for the Earth. They believe that we should leave God and nature to feed our planet. Other, non-religious people, simply just believe that it is wrong to create new life forms or swap genes around between species.
Its Unsafe
Allergen levels have risen considerably. Before 1997, and GM foods, 4% of all children had some sort of digestive allergy. Since then, it is now up to 18%, a considerable rise. Many people point the finger at genetic engineering for this spike. There are also higher levels of toxin that is naturally found in the food.
For the golden rice, there are numerous problems including
-the vitamin levels may not actually make a difference, so is it worth the risk?
-there are fears that the new rice may contaminate with wild rice, therefore disrupting nature.
-food from the GM plant may hurt people
-seed for GM plants may be expensive
For herbicide-resistant crops, problems include
-the development of herbicide-resistant weeds, causing endless problems for farmers
-decrease in biodiversity (variety and variability of life on Earth), as fewer weeds survive, loss of shelter and food for animals.
Conclusion
I believe that genetic modification is not ready for use as it is not 100% safe to use yet, as I have found from my research. I do not believe it is ethically correct either, but as our population increases, it becomes a case of needs-must, and for our world to survive, genetic modification will become a necessity.
Even Brexit makes an Impact (again)
The EU is strongly against all types of genetic engineering. There is only one license that permits EU countries to grow their own GM crops. This doesn’t mean that GM crops cannot be imported, however. Farmers in Britain are in fact supporters of genetic engineering, and that is possibly why 60%+ of farmers voted leave. This therefore means that we could see more new developments in genome technology once Britain has exited the European Union.
Bibliography
Nhs.co.uk
My biology textbook
Usbourne Introduction to DNA, genes and chromosomes
BBC bitesize genes
Khanacademy.org
Debate.org
Thenextgalaxy.com
Prezi.com
www.who.int( World Health Organisation, genetic modification)