"Looking Back, Looking Ahead"
What makes a person appear as he or she is? Why do the same diseases tend to occur in family members? Questions such as these could not have been answered without the help of genetics. Webster's Concise English Dictionary defines genetics as "the science of heredity," but these words do not even begin to describe what genetics is concerned with, and how much it has contributed to our knowledge about heredity, DNA, and genes. Genetics deals with the study of genes to possibly change or improve organisms (Oleksy 127) to have more advantageous characteristics in their environments. Crops can be improved by changing the genotype of a plant to better survive harsh weather. The whole idea that genes can control so many aspects of our lives fascinates me so much. The significance of genes has only recently been discovered, for scientists now know that genes control our personalities, mannerisms, and the diseases we contract.
Today, geneticists are able to study the DNA of organisms and determine which diseases are congenital, meaning genetically transferred (Byczynski 54), that is, passed on from parent to offspring. How did the knowledge of these areas advance to such conclusive studies? Where do we stand in the field of genetics today? What might we know about genetics in the future? As technology advances, the knowledge of genetics is sure to increase, especially as the completion of the Human Genome Project draws near.
Where did it all begin? Gregor Mendel, an Austrian botanist and monk often referred to as the "Father of Genetics," was one of the first to begin study on heredity and genes. In 1900, when the science of genetics was just beginning, Mendel's work had already been completed and published in 1866 ("Genetics"). Mendel worked with garden pea plants and observed a pattern in heredity over several generations of breeding the plants (Byczynski 23). He also discovered that a characteristic could be determined by dominant and recessive hereditary factors later known as genes (Edelson 20). Still, his work was not held in high regard during his time, and his publication was lost as fellow scientists disregarded his important discovery. Decades later, in 1900, three plant breeders simultaneously discovered the forgotten experiments of Mendel and the science of genetics began to evolve from that point on ("Genetics"). These three scientists, Hugo de Vries, Karl Correns, and Erich von Tschermak, resided in three different countries, Holland, Germany, and Austria, respectively (Edelson 18). By looking back at Mendel's experiments, the three scientists could see that there was a definite ratio of 3:1 or 75 percent to 25 percent in the second generation for each characteristic in the plants (Edelson 19).
Throughout the century, many other scientists explored genetics and heredity. William Bateson, a British biologist, conducted experiments that reinforced the idea that each trait is controlled by a different gene (Edelson 21). Then, in 1904, American scientist Walter Sutton investigated chromosomes, which are structures containing the DNA and genes located inside the nuclei of cells. Sutton noticed a relationship between chromosomes and genes because offspring receive two sets of chromosomes, one from each parent. Thus, the chromosomes must carry genetic information. Because there are a greater number of traits compared to chromosomes, Sutton found it logical to assume that chromosomes are the packages containing the genes (Edelson 21). Between 1909 and the mid-1930s, Thomas Hunt Morgan of Columbia University and W. E. Castle of Harvard University headed teams that studied the species Drosophila melanogaster , commonly identified as the fruit fly (Arnold 31). Morgan noticed that certain characteristics were often linked, yet this was not always the case. The linkage of the genes must have been influenced by their positions, or loci, in the chromosome because of the crossing over and exchange of genetic information that occurs in meiotic cell division (Arnold 32). Morgan and his group were responsible for creating the first gene maps, which indicate how genes are arranged in the chromosome within which they are contained (Yount 20). In the 1930s, most geneticists anticipated that a gene must be compounded of complex chemicals such as proteins, since nucleic acids seemed too simple to carry genetic information (Yount 39). In 1944, however, Dr. Oswald Avery of Rockefeller University worked with pneumonococcus (Yount 38), a pneumonia-causing bacterium, and found that genes are composed of the nucleic acid named deoxyribonucleic acid, which is better known as DNA (Oleksy 68).
DNA became the focus of genetics after Dr. Avery discovered the nature of genes. Nine years later, in 1953, Drs. James Dewey Watson and Francis Harry Compton Crick discovered that DNA's structure exists as a double helix (Byczynski 45). In 1965, the genetic code was deciphered when protein synthesis was achieved in a test tube with the use of RNA (Oleksy 68). In 1975, Drs. Stanley Cohen and Herbert Boyer began the age of genetic engineering when DNA was cloned from recombinant DNA that was inserted into host bacteria (Oleksy 68). Advances in genetic research of diseases occurred as sickle-cell anemia was identified before birth by analysis of DNA in 1978 (Oleksy 69). In 1982, progress in human genetic research reached a peak. Human insulin could be made by use of recombinant DNA techniques, and a method for determining the location of genes on a chromosome was developed (Oleksy 69).
Genetics has come a long way since 1900, when the science was first beginning. We now know how to diagnose certain diseases in a child before he or she is born. Also, we can actually read the code of DNA, which consists of the four nitrogenous bases: the two purines, adenine and guanine, and the two pyrimidines, thymine and cytosine (Edelson 28). Thus, when the Human Genome Project began a decade ago, scientists knew that they were close to decoding something huge--an entire human genome (Hayden 88). All the scientists needed to do was to wait for the sequencing machines to finish decoding the seemingly endless code contained in the human DNA sequence. The goal of deciphering the code was projected for 2005, but scientists have recently announced that they would complete a first draft of the genome by the spring of 2000 (Hayden 89). Thus, the Human Genome Project, if everything goes as planned, will finish five years earlier than originally planned. The National Human Genome Research Institute, the organization that oversees most of the activities in the Human Genome Project, might have sped up its work because of competition. In May 1998, a private company, Celera Genomics, headed by Craig Venter, announced that the company would start its own project of sequencing the human genome (Hayden 89). With a strategy called "shotgun sequencing," the company expects to have a complete reading of the human genome before the year 2000 has passed (Hayden 89). However, another event will be occurring before the excitement of the disclosure of the human genome in the spring of 2000. In February 2000, scientists of the Drosophila Genome Project expect to unveil the fully sequenced genome of the Drosophila melanogaster , the species of fruit fly used in Morgan's experiments (Hayden 90).* Many other organisms are waiting to be sequenced; these include plants, which are especially important because of the agricultural advantages they could present. But what will we be able to understand after all this sequencing is over and done? Venter explains that since every disease and trait has a genetic component, knowing the locations of genes that cause certain diseases might aid scientists in the search for possible reversals to these diseases (Hayden 90). Many projects are set to be completed in the year 2000, and one can be sure that 2000 will be the year of all years for genetics.
By 2100, scientists are hoping to understand all the data that they will have collected from the sequencing of various genomes of different species of organisms. Even Venter says, "We'll really begin in earnest to try to understand that [every single disease and trait has a genetic component] in 2000. And that's what will be going on for the next 100 years" (Hayden 90). No one knows for sure what will actually happen by 2100, but it will be a new age of genetics, one in which scientists work diligently to prevent currently incurable diseases such as cancer, Alzheimer's, and diabetes, by studying the genes that are associated with them. As Thomas Hayden says, "2000 will see the start of a new era in which humankind starts to take control of its biological destiny" (Hayden 90). Genetics is really starting to pick up the pace, and the excitement of the approaching discoveries is sure to bring up controversies all over the nation.
Genetics is becoming an increasingly important field of science, and I am planning to pursue a career somewhat linked to genetics. The science of our future is held in genetics and I am sure to be a part of the chance of a lifetime--the chance to understand the human genome and to prevent patients from dying of diseases that we currently cannot cure or protect them from. Our future is sure to be exciting as the promise of so many discoveries draws near.
*In fact, in March of 2000, at their annual meetings in Pittsburgh, PA, fruit fly scientists announced the virtual completion of the Drosphila melanogaster genome.
|February: Mendel presents all of his information|
|Mendel's paper is published but is lost because of disinterest|
|Mendel dies of kidney disease|
|Mendel's work is rediscovered by three scientists|
|Walter Sutton suggests that chromosomes contain genes|
|The term "genetics" is coined by William Bateson|
|Morgan works with the fruit fly|
|Dr. Avery discovered that genes are composed of DNA|
|Watson and Crick meet in Cambridge, England|
|Watson and Crick discover the structure of DNA|
|Genetic code is deciphered|
|Many advances occur, including the production of human insulin|
|Human Genome Project is started with Watson as head|
|May: Celera Genomics announces that it will have its own human genome sequenced|
|March: Human Genome Project announces that a draft will be ready in spring 2000|
|February: Projected date for the unveiling of a fully sequenced Drosophila melanogaster genome|
|Spring: Projected date for the unveiling of a fully sequenced human genome|
Arnold, Caroline. Genetics: From Mendel to Gene Splicing. New York: Franklin Watts, 1986.
Byczynski, Lynn. Genetics: Nature's Blueprints. San Diego: The Encyclopedia of Discovery and Invention. 1991.
Edelson, Edward. Genetics and Heredity. New York: Chelsea House Publishers, 1990.
"Genetics." In Microsoft® Encarta® Encyclopedia 99. (Version 99). [CD-ROM]. Microsoft Corporation, 1998.
Hayden, Thomas. "The Year We Control Our Destiny." Newsweek. December-February 2000: 88-90.
Oleksy, Walter. Miracles of Genetics. Chicago: Childrens Press, 1986.
Yount, Lisa. Genetics and Genetic Engineering. New York: Facts On File, Inc., 1997.
Less than 1 period
Supplement a study of genetics with an activity drawn from this winning student essay.