Genetic Engineering Essay, Research Paper
GENETIC ENGINEERING
PURPOSE: To better understand how genetic engineering works
and where it is going in the future
I. Definition
II. DNA
A. Definition
B. Chromosomes
C. Mutations
III. History
A. Gregor Mendel
B. DNA debate
IV. Mapping
A. Kinds of DNA
B. Humans Genome Project
C. DNA fingerprinting
V. Splicing
A. Recombining DNA
a. Problems
b. Rules and regulations
B. Cell fusion
C. Overlapping method
VI. Future
A. New antibodies
B. Cloning
GENETIC ENGINEERING
“Life is beginning to cease to be a mystery and becoming practically like a cryptogram, a puzzle, a working model that can sooner or later be made.” 1 This describes what happened to the mystery of life after the new science of genetic engineering. We can cure diseases, make bigger tomatoes, and soon, we will even be able to decide how our children will look. Amazing, isn’t it? That’s why I chose genetic engineering as my topic.
What is genetic engineering? It’s any manipulation or artificial modification of the process of heredity and reproduction. 2 This just means that it is any changing of DNA, the basic building block of all life on our planet, from viruses to dinosaurs. Why would we want to change the DNA of organisms? Should we really be tampering with billions of years of progress?
What are some real life uses of genetic engineering? First, we could find out more about the origin of life on earth. Next, there is a worldwide overpopulation problem. With genetic engineering, we could help the dilemma just by growing larger fruits and vegetables, or even larger cows. Another option is to go right to the source of the problem and alter women’s DNA so they could only have one baby in their lifetime. This can be done now, but it is not ethically accepted. Also, it will help us better understand where life on earth is going. How? Simply because we will have control of all life on the planet. Some people are wary of this idea, that’s why there are laws against cloning humans and strengthening viruses.
Genetic engineering will also allow us to cure various diseases; we have already found the cause of sixty percent of cancer, now it’s just a matter of using that knowledge to make a cure. 3 Public health standards will be much higher once we prefect recombinant DNA techniques. One vaccination is all that will be needed for an entire lifetime. Also, gene therapy will be used to cure almost any disease, not rest or other time consuming treatments. Agriculture will be a more exact science. Livestock will give us more milk, meat, and other products. We will be able to make much larger, healthier fruits and vegetables and need only one serving of fruits, vegetables, and grain a day.
The basis of all genetics is DNA. A molecule so small that it can’t be seen but with the best scanning electron microscope. Yet, it is huge in comparison with other molecules. DNA is found in every cell in your body except red blood cells, which have no nucleus. Each molecule of DNA is called a chromosome and is so long that if you unwounded it would wrap around the earth many times. How can it be so long and fit in a cell so small? It’s winded into a coil, and that coil is winded into another coil.
The actual molecule itself is shaped like a double helix, which looks like a twisted ladder. We found out it was shaped this way by using an imaging technique called x-ray crystallography. X-rays are bounced off the DNA and the way they bounce back is analyzed. 4 It’s like throwing tennis balls at someone in the dark and seeing how they bounce back to tell how they look.
Just one molecule of DNA can have thousands of genes. A gene is one pieced of DNA that controls something like hair color, height, or what diseases you’re susceptible to. Each rung of the ladder is a combination of two bases locking together. The four bases are acids and are usually represented by the letters A, T, C and G. 5 A only bonds with T, C only bonds with G. This makes DNA both incredibly simple to duplicate, but deviously complicated to understand.
Different organisms have different amounts of DNA. A virus that attacks E. coli, a bacteriophage, has only three genes, while E. coli itself has one thousand. 6 Most geneticists like to study the fruit fly because it has one gene for each piece of DNA. Humans have about 500,000 genes. 7
Chromosomes are one big molecule of DNA wrapped up neatly. Most chromosomes are “X” shaped. Each also has an exact duplicate, this is another way DNA minimizes the number of mutations. Many animals and even a few bacteria have more chromosomes than we do. Monkeys have twenty-seven pairs, cows have thirty pairs, and even onions have eight pairs of chromosomes. 8 It’s the quality, not the quantity of chromosomes.
How are all those A’s, T’s, C’s, and G’s used to describe how to make a virus, cow, or even a human? Each three bases, like CTG or AAC spells out a different amino acid. When you string millions of these acids together, you get a cell. However, people have different kinds of cells, like brain cells, heart cells, or skin cells, how does DNA know how to make the different kinds? Our DNA is arranged in chromosomes. There are twenty-three pairs of chromosomes in humans. 9 The different chromosomes are like books of an encyclopedia. Brain cells only look at their book, while liver cells only read their book.
Why does DNA use only four acids to “spell out” an organism? Why not twenty, the total number of amino acids? 10 Then it would only need one base to make each amino acid instead of three, making it three times shorter than it is now. Geneticists don’t really know for sure, but they think it’s to minimize the number of mutations in the organism. You could probably do much better on your spelling tests if you only had four letters, instead of twenty.
Mutations are deformities in DNA usually caused by some form of radiation. It’s estimated that each human is carrying three to eight mutations in their DNA. 11 Most of the time none of the changes are visible. Serious mutations are called genetic diseases, like birth defects, hemophilia, or sickle cell anemia. 12 If the changes are too serious the DNA chooses to kill the organism, instead of letting it live with the mutation. Drastic DNA mutations in the womb account for most miscarriages.
Genes can be turned on and off. For some reason, we have a gene that allows us to regenerate limbs if they are somehow cut off. This gene is still in our DNA, but it has been turned off. If we could just turn it back on, amputees could regenerate their arms or legs.
We have also found a molecule, called p53, which plays a large part in whether we will get cancer. P53 is turned on or off by a gene in one of our chromosomes. What p53 does is sit and watch the DNA to see if it’s making a mistake copying. If something goes wrong it springs into action and will immediately latch onto the DNA and not allow it to copy itself unless it repairs itself first. If the DNA does not repair itself, p53 will just kill that cell, ensuring that this mutation will not be passed on. Sixty percent of people with cancer have some kind of problem with this molecule. Either it is not present, or it can not reach the DNA. 13 As soon as we learn to use turn on this gene in people without p53, we’ll be able to easily stop the growth of cancer completely, and even prevent it. We have found the cure for cancer, and it’s in ourselves.
Although genetics started over a hundred years ago, genetic engineering is a relatively new science. The first time a cell was successfully engineered was in the early 1970’s, even though the restriction enzyme, a chemical used to cut DNA into pieces, was discovered twenty years earlier. Now that geneticists have a better grasp of the basics of genetic engineering, progress is much faster.
Gregor Mendel was the creator of genetics. He had thousands and thousands of pea plants he bred to study heredity. He was born in 1822 and died sixty-two years later in 1884. 14 In the beginning, he hoped to be a high school teacher, but he failed the teacher’s exam three times before giving up and deciding to become a botanist and continue his research in heredity. In 1865, he published his pea study, which he had worked on for five years. 15 He made hybrids from different pea plants, a hybrid is a plant or animal that is the result of crossing two or more varieties of a plant or animal. In hybrids, every organism in the first generation is an exact copy, or clone, because the genes inside that organism skip generations and those genes aren’t visible in the first generation.
A Harvard student was researching SV40, a tumor that affects small animals. 16 He injected a small part of a tumor into E. coli, a bacteria contagious to humans. His colleagues urged him not to do the experiment. That event that triggered the DNA Debate in 1971 about the benefits vs. the dangers of genetic engineering. 17 Is it safe to use genetic engineering? Many were afraid the scientists would create a terrible new disease. The geneticist said this was silly, and it would be used to cure diseases. What was so great about genetic engineering? It was a more effective, cheaper way of making biological products like hormones, vitamins, antibodies, enzymes, and antibiotics. Third world countries would have an increased food supply. We would have a better understanding of the cure for cancer. Also, new approaches to the world’s population problem and an increased understanding of the world. Why were some people against genetic engineering? Some thought that the geneticists would accidentally create a worldwide epidemic of an uncontrollable disease. Genetic engineering could also be a powerful tool for dictators, militias, and terrorists. Terrorists would have no trouble at all sneaking into the country with a few deadly viruses. Also, many don’t like the idea of scientists domination all life on the planet including humanity.
Why so little change even after all the millions of years? It is said that if a cave man from the ice age was dressed up in a business suit, he could go unnoticed. It seems like the DNA would have changed after many mutations by now, why not? First, serious genetic mutations aren’t passed on to the next generation because it causes death, in the case of a fetus, a miscarriage or stillbirth. Second, every organism has two copies of its DNA, in case something happens to one, the backup takes over and immediately copies itself and destroys the bad copy. Third, there is also a surplus of information. We don’t need most of the data in our genes. Much of the time, genes cross-reference each other. One gene may reference another, and that one references back to the first. Finally, DNA implements a fail-safe concept. It’s extremely hard to get to the DNA, in the very center of the cell. That’s why most mutations are caused by radiation, which easily penetrates the cell. Even if the DNA is changed a little, it most likely will have a catastrophic results, sometimes even death. This ensures that the mutated DNA isn’t passed on.
Before we can start engineering the DNA of organisms, we need a map of their DNA. There are two basic types of DNA structures. We will compare and contrast two bacteriophages that attack E. coli, a bacteria that lives in the intestine of humans. First, there’s MS2. This virus’s genetic code has been completely mapped, all 3569 bases of it. 18 It has three genes, the first one tells it how to attack and get into it’s host, E. coli. The second tells it how to make its protein coat, the body of the virus, and the last gene tells it how to reproduce. It has huge gaps of about fifty bases in between each gene to separate them. The DNA of MS2 surprisingly resembles a file in an old computer. The other bacteriophage that attacks E. coli, Phi X 174, is much more successful at its attacks. It has a unique way of organizing its DNA. It uses compression to get more information out of it’s tiny piece of DNA, so it can store all the information that the other virus has, plus more tactics on how to attack E. coli.
Right now geneticist are working on a worldwide research effort with the goal of mapping the entire human DNA and finding an estimated 100,000 genes. With this knowledge, we will be able to diagnose and treat over 4,000 genetic diseases. 19
Another type of DNA mapping is DNA fingerprinting which is used in mostly in criminal investigations. Even with a small sample you get an almost one hundred percent accuracy. To fingerprint a sample of DNA, first you must separate the DNA from the blood in a centrifuge. Then, cut it into little pieces using enzymes that act like scissors on DNA. Next, sort the DNA fragments by length by putting them in a plate and applying an electric charge. After that, another enzyme separates the DNA at its seams. Now, artificial pieces of DNA are made radioactive and attach to the separated DNA strands. The pieces of DNA that have been radioactive are now visible and can be seen in a x-ray.
There are three kinds of gene splicing, each with it’s benefits and drawbacks. The first kind, the recombinant method, is a type of molecular genetics, genetics done at an extremely small scale. To recombine DNA, first, get a plasmid, a small circular piece of DNA, from an organism and cut part of it off. Next, part of a piece of foreign DNA is cut off and combined with the plasmid. Then, the new DNA is put into another organism, where the organism begins to reproduce the new DNA.
There are some drawbacks to the recombinant DNA technique. The development of an animal that has recombined DNA is rigid compared to that of bacteria or plants. Also, this technique only allows production of one kind of cell, such as only liver heart cells, or only skin cells. This technique can only organisms with each gene in a different chromosome, which means that mammals can’t be engineered with recombinant DNA.
To use this technique to engineer DNA, you must follow rules that are internationally accepted about recombining DNA. No cloning disease causing microbes or cancer causing viruses. No engineering organisms to make powerful toxins. No engineering to increase strength or range of plant diseases. No making organisms drug resistant unless their species has acquired it naturally first. Most important, no releasing engineered organisms into the environment. 20
The second technique is called cell fusion. This method works on a larger scale, but still much too small to see. Cell fusion is just what it sounds like, joining two different kinds of cells into one. Most of the time the Sendai virus is used to connect the two cells. First, the virus is treated with ultra-violet light so it can’t harm the cells. Then, let it attack two cells that are touching each other. The cells will then fuse into one. So far, we have made mouse-hamster, mouse-human, and even plant-animal cells using this technique, although most of the genes of one or the other cell are lost after a few divisions.
The final method is the overlapping method. The steps are basically the same as the recombinant DNA technique. What makes this technique unique is the way the DNA is combined. DNA is attached by overlapping when connecting the strands. This leaves a small edge of DNA; the next strand they want to attach automatically attaches to the left over edge.
Genetic engineering is a new science. So far, flowers, vegetables, grains, cows, horses, dogs, and even cats have been genetically engineered. That’s not counting all the bacteria and viruses. We are just beginning to understand the possibilities of using genetic engineering not to mention the implications.
We will soon be able to use cell fusion to engineer antibodies to attack certain viruses. It’s just a matter of time. The engineered antibodies will be able to kill any virus they are engineered to kill instantly.
The most startling advancement in genetic engineering has to be the recent cloning of a ewe. A clone is an exact genetic copy of another organism. Identical twins are just clones of each other. They made the ewe clone by first taking some cells from the udder of a female ewe and placing them on a culture with nutrients. Next, an unfertilized egg is taken from another female ewe, and stripped of its genetic material. DNA from the cells of the first ewe is combined with the egg with no DNA. The new egg is then put into a culture and a small shock is applied to the cell to start the development. Six days later, the embryo is put into yet another female ewe. Months later, a female baby ewe is born that is an exact genetic copy of the first ewe. One interesting thing to notice about this cloning process is that no males were involved.
In conclusion, we are still trying to understand genetic engineering. We haven’t even completed a map of our own DNA. Even though, I think we should try to progress as fast as possible. There should be no laws to hold back the advancement of genetic engineering.
This paper is also at http://www.benray.com/genetics/