Genetic Manipulation: Advantages and Disadvantages
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Science on the other hand, fills my brain with questions and answers the knowledge that I crave. The theory of evolution does not dismiss there is a God. It is a theory trying to explain the beginning of life, how we evolved. The Old Testament professes to do the same thing, however, the stories are symbolic in their meaning. I am a Roman Catholic, and our dear Pope John Paul II acknowledged evolution as more than a hypotheses. Only the divine soul is untouched by evolution (Jurmain et al. 2010:44).
The fact that some fossils are not preserved does not disprove evolution. Many species might not have left fossils. Some organisms just do not fossilize well. The geological record is not perfect. The fossils are not laid out perfectly waiting to be discovered by paleontologists. Chances are it is highly unlikely that an organisms remains will become fossilized, rather than decomposed. For the remains that do become fossilized, their preservation is unlikely due to erosion, earthquakes, volcanic eruptions , etc;
Evolution continues to be rejected by some religious conservatives and fundamentalists. A lot of them believe that evolutionary biology ignores that God exists. They state that it does not account for how the world was really created according to the scriptures in the Bible. There have been numerous efforts to block teaching of evolution in U.S. public schools since 1968. The US Supreme Court overturned the first case in Arkansas stating that there could be no law barring the teaching of evolution on the grounds that it breached the separation of church and state as stated in the U.S. Constitution.
Fourteen years later the federal courts rejected a statute to teach both "creation science" and "evolution" in the public schools. The courts stated that "creation science" was not actually a science.
To try and "get around" the law of separation of church and state, evolution opponents began to propose the teaching of "intelligent design". They stated that it was non religious, and a scientific alternative to evolution. Intelligent design claims that the living world was too intricate to have been made by the workings of natural selection. That some living things were too complex to have been developed by evolution and could have only have been created by an intelligent designer. But, they did not identify this intelligent designer. This presentation again was blocked by a federal district judge who found "intelligent design" was not a science (Jurmain et al. 2010:44).
What can be done to correct this controversy, or should it be corrected? Why?
Although I don't agree with the Christian fundamentalists opinion, my answer is, no.
Why? It is called the First Amendment.
Describe and evaluate some of the positive and negative consequences of genetic manipulation
Genetic engineering entails the manipulation of DNA. The tools in this process are very important for the restriction of so called enzymes, which are produce by various species of bacteria. A particular sequence of a chain of nucleotide bases, can be recognized by restriction enzymes. The nucleotide bases that make up the DNA molecule; cut the DNA at that location. Parts of DNA formed in this way are joined using enzymes called ligases(joining of two enzyme molecules to form a covalent bond, accompanied by the hydrolysis of ATP(adenosine triphosphate))
Positive side of genetic manipulation
Genetic therapy entails supplying a particular function to a gene, and in turn to cells that are lacking that function. The intention is to correct a genetic disorder or an acquired disease. One type of gene therapy used today is, somatic cell therapy. It is similar to an organ transplant. One or more specific tissues are targeted for treatment by therapeutic genes from the lab or the tissue is removed and replaced with the treated cells and given back to the patient. Researchers have had success with somatic cell gene therapy for the treatment of blood, lung, liver disorders and cancer.
Another positive side to genetic manipulation also involves the health industry. The manufacturing of recombinant factor VIII, a blood clotting agent missing in patients with hemophilia A. Practically all of the hemophiliacs who were treated with factor VIII before the mid 1980's contracted AIDS or hepatitis C from viral contaminants in the blood that were used to make the product. Now donor blood is screened for the presence of HIV and the hepatitis C virus. The process now includes inactivating the viruses if they prove to be present. The possibility of a virus contamination is eliminated completely by the use of "recombinant factor VIII".
Negative side of genetic manipulation
Explanation of Cloning: A technique that is a process of several stages.
- An egg is taken from a donor animal
- The nucleus is then removed from the egg.
- The nucleus containing the DNA is taken from the tissue cell of the animal being cloned.
- The nucleus is inserted into the donor egg cell.
- The fused egg is then placed in the uterus of a surrogate mother.
- When that mother eventually gives birth, if all goes well, the baby is genetically identical to the animal that provided the tissue cells that contained the DNA.
I understand the potential benefits that genetic engineering has for the future of this world, however, the thought of it getting into the "wrong" hands terrifies me. My main area of concern is cloning. From the beginning, back in 1997 when I heard on the news about the sheep, Dolly, being cloned in Scotland, my heart sank. There is even talk of people ordering what type of children they want, as if they were ordering from a dinner menu. I knew eventually that people would be cloned. There is evidence they have already. People are desperately waiting for transplants. Why are we not using the clones vital organs? This is something would like answered.
Would you agree with your textbook authors when they say: Indeed it would not be an exaggeration to say that this is the most exciting time in the history of evolutionary biology since Darwin published "On the Origins of Species?"
Would you agree or disagree with this statement? Why? Please provide some detailed examples?
Yes, I would agree. In my younger days, I worked as a chemotherapy technician in Children's Hospital, Boston. I worked closely with one little girl who was born without a stomach, preparing parenteral nutrition for her daily basis. Children also dying at a very young age of diabetes. But due to the amazing research done in genetics, and recombinant DNA technology, children have a much better chance of reaching adulthood and leading normal lives.
Regarding the field of anthropology, the sequencing of human genes in the Human Genome Project. The progress being made in comparative genomics is terribly exciting. Personally, I can't wait to hear the DNA comparison results of the Neanderthal, modern human, and nonhuman primate.
What is natural selection?
The theory of Natural selection is actually the "key to evolution." It is based on the following processes that include:
- Biological variation within all species
- Individuals within a species that have favorable traits are more likely to survive in their environment and produce offspring.
- The environment of the species determines whether or not a trait is satisfactory or not.
- Traits are inherited and over a period of time, favorable traits will be passed on generation to generation and become more common in the population.
- Isolation of a species may lead to the formation of a new species due to inhabiting a different environment and will in turn adapt to that environment.
- Natural selection only operates on an individual within a population, but it is the population that evolves.
Why is genetic variation necessary for the process of natural selection to operate?
Genetic variation plays a significant role at the microevolutionary level, producing evolutionary change. Directional evolutionary trends can only be sustained by natural selection. Individuals who carry a particular allele or a combination of alleles will produce more offspring than other individuals with different alleles. The frequency of the new allele in a population will increase slowly from generation to generation. This process is compounded over hundreds of generations for multiple loci, the result being a major evolutionary change(Jurmain et al. 2010:107).
What are the sources of genetic variation?
Mutations: When there is a change in the DNA molecule that means there is one type of mutation and that multiple genes occur in two or more forms called alleles. If an allele to another allele, or if the gene is altered in some way, a mutation has just occurred. Alleles are, in fact, a direct result of a mutation. The substitution of simply one DNA base for another, a point mutation, can cause a change in an allele. However, to be important to the evolutionary process, the point mutation has to occur in the sex cells. This is so the mutation can be passed on from generation to generation.
No changes in phenotype due to mutations
No evidence of a change on the phenotype of an organism due to mutation. Mutation occurred maybe in a stretch of DNA with no function, or perhaps the mutation occurred in a protein-coding region, but ended up not affecting the amino acid sequencing of the protein.
Small change in phenotype due to mutations would for example be a single mutation like a cats ear slightly curling back.
Big change in phenotype due to mutations
This would create some major phenotypic changes. DDT resistance in insects are usually caused by single mutations. A single mutation can also have very strong negative effects on an organism. Mutations that would cause the death of an organism are called lethal's.
Gene flow Migration is used here to refer to the movement of people. This occurs when the exchange of genes between different groups of migrants interbreeding. It can also occur when an individual(s) move temporarily and produce some offspring in an entirely new population. This way they have left their "genetic contribution".
An example of gene flow: Happens a great deal in war. When male soldiers are stationed in remote parts of the world and impregnate the native women of that country and then the male returns to his native land. The impregnated native women in the remote country represents the "gene flow".
Genetic drift is known as the random factor in evolution. The population size is its entire function. Drift only occurs because a population is small. If an allele is rare in a very small population of less than 400 people, there is a very great chance that it will not be passed down to the offspring. Eventually, the allele may disappear entirely. In this instance genetic variability has been reduced drastically. Genetic drift can cause big losses of genetic variation for small populations.
An example of genetic drift: The B allele was evidently not passed down to generations of Blackfoot people. There is evidence that present populations are deficient in genotypes that contain the B allele (BB, BO and AB). When the populations became greatly reduced in size, some genes may not have been passed on to the next generation. This phenomenon is referred to as a "genetic bottleneck." As a result, genetic variability may have been severely reduced in succeeding generations.
Founder effect is a type of genetic drift and is seen in human and non human populations.
An example of the founder effect is the Baptist German religious "sect" that settled in Pennsylvania in the early 1700's. These families didn't marry outside their own religious sect. There has been evidence of some dramatic changes in their gene frequencies. For example; the type A blood in the "sect" resulted in 60 percent. United States is 42%. It is 45 percent for the "sect" in West Germany. They also have fewer people with certain recessive traits, such as "hitchhiker's thumb" and attached ear lobes, compared to the U.S. population as a whole. The founder effect helps explain the high frequency of dwarfism and polydactylism (extra fingers) in the Amish of Lancaster Pennsylvania. The colony began when at least one of the individuals carried these traits.
Recombination is a source of genetic variation that introduces new gene combinations into populations.
For example: Siblings are never genetically identical to either of their parents or to each other (unless they are identical twins.)This is because when organisms reproduce sexually, some genetic ââ‚¬Å“shufflingââ‚¬Â occurs. This brings together a new combination of genes.
How is natural selection related to environmental factors?
All the evolutionary factors of mutation, genetic drift, gene flow, and recombination, interact to form genetic variation. Genes are then distributed within the populations. There isn't any long term direction to any of the above factors, but for adaptation and the evolutionary process to occur, the gene pool of the population needs to change in a certain direction.Some alleles need to consistently become more commonplace, while other become less common. Natural selection can cause a change in direction in allele frequency relative to specific environmental factors. If there is to be a change in the environment, then the selection pressures will also change, and a shift in allele frequencies is called "adaptation". Now if there are long term environmental changes in the same direction, then allele frequencies would also shift very gradually over time.
Example:Hemoglobin S (Hbs) which is an abnormal form of hemoglobin that is formed from a point mutation gene, produces part of the molecule of the hemoglobin. If an individual inherits this allele from both parents, he or she will have sickle cell anemia. HbS is a mutation that occurs in all populations occasionally, but the allele in generally rare. HBs, however, is more common in central Africa where it reaches 20% of the population. With the devastating effects of the HbS homozygotes, one would think that natural selection would have acted on eliminating it. But that is not the case. Natural selection has actually increased the frequency of HbS. This is because of the disease malaria. People with one HbS and one HbA allele (heterozygotes with the sickle cell trait) have red blood cells that contain hemoglobin S. Hemoglobin S is not a suitable environment for the malarial parasite. So having HbS is beneficial, because it protects that person from malaria. In this instance, malaria is the selective agent. and favors the heterozygous phenotype. In this part of the world, individuals with sickle cell anemia trait have a higher reproductive success than those with normal hemoglobin, because they are more apt to die of malaria (Jurmain et al. 2010:105).
Discuss genealogy of the Blue Fugates of Kentucky.
Describe Mendelian principle of inheritance as well as a phenotypic effect of an enzyme deficiency.
Mendel discovered through his experiments with plants, that the inheritance of traits was not due to blending as he originally thought. He found that specific units (genes) of inheritance were passed down from generation to generation. No matter what trait Mendel selected for the second generation of the plants, it would show a ratio of 3 to 1. This meant that there were 3 dominant genes to every 1 recessive gene. Mendel realized that this 3:1 ratio occurred in later generations as well. He had found the key to understanding "inheritance."
Mendel came to three very important conclusions from his experiments
- The inheritance of each trait is determined by units(genes) that are passed on to descendents and are unchanged.
- An individual would inherit a gene from each parent for each trait.
- A trait just may not show up in an offspring but could be passed on to their offspring.
Mendel's observations have been summarized in to two principles:
The principle of segregation and the principle of independent assortment.
According to the principle of segregation two members of alleles separate from each other in the formation of sex cells (gametes) Half of the gametes carry one of the allele and the other half of the gametes carry the other allele.
Principle of independent assortment-Genes for different traits are assorted independently from one another in the formation of sex cells.
I feel the principle of segregation applies in the case of the blue Fugates of Kentucky. It was determined that the Fugates inherited an autosomal recessive trait. Both Martin Fugate(heterozygote) and his bride Elizabeth Fugate(heterozygote) had one recessive allele each of this disorder. Since both Martin and Elizabeth were both carriers, there was a 25% chance of their offspring being affected. There is usually a predictable phenotypic ratio of 3:1.
The family would marry people who lived close by and this intermarrying continued. The community was isolated, without roads. When the railroad was completed 30 to 40 years later, roads were built and they started venturing out and marrying outside their "community." The strain of the inherited "blue" gene began to disappear. The recessive gene was not likely to find a mate with the same recessive gene. A baby named, Benjy Stacy was born blue, 100 years later. He had the recessive gene from both his mother and fathers side. His blue color, however was only temporary. It was "assumed" that Benjy had just inherited one gene of the condition, and being a baby had a smaller amount of the enzyme diaphorase, and it built to normal levels as he got older (Jurmain et al. 2010:86-89) and Fugate family literature.
Why do we see this rare, phenotypic deficiency?
It was first seen in Alaskan Eskimos and Indians. It is a human genetic disease. The gene is located at chromosome 22. In normal people, there is a dominant, allele that is responsible for the production of the enzyme diaphoreses. Normally hemoglobin is converted into methemoglobin(a brownish compound of oxygen and hemoglobin) at a very slow rate. Diaphorase in normal blood, changes the methemoglobin back to hemoglobin. The homozygous children of the Fugate family, lacked the enzyme diaphorase. therefore this conversion could not take place. Therefore, all of their hemoglobin in their body was considered useless. Instead they had a mutant allele that produced an inert enzyme that was unable to reduce the hemoglobin.
What is the nature of the evidence supporting punctuated equilibrium?
The theory was advanced by two American paleontologists Eldredge and Gould. They agreed that the fossil record was incomplete, but that it could not be incomplete enough to account for the near absence of the gradualistic change from the fossil record. They said that species originate too quickly for the normal geological processes to record the event; a single bedding (a thin layer of sedimentary rock)often compresses more than tens of thousands of years into a thin slice. Speciation usually occurs when small populations cut off from the interbreeding with groups, evolving rapidly in isolation. With fewer people in an isolated population, the favorable mutations spread more readily. A small, isolated, evolving population may become extinct and may not leave a trace of a fossil record. Eldredge and Gould said that if it does remove itself from its isolation, and spread over a much wider area, its likely to be seen in the fossil record as making a punctuational appearance, fully formed.
The nature of the evidence supporting punctuated equilibrium was from the paleontologist, Cheetham. He gathered a large sample of bryzoan fossils from the Caribbean and surrounding regions. He painstakingly classified them into 17 species using 46 microscopic characteristics of their skeletons. Measured their length, dimensions of pores, and all the orifices on the fossils. He then arranged them into a family tree. He analyzed them and split a single species into several species. The abruptness in the tree, appeared more clear to him and stronger than ever. He concluded that through 15 million years of the geological record, these particular species persisted unchanged for 2-6 million years. Then in less than 160 thousand years, split off in to a new species. This new species would coexist continuously with its ancestor species. This was his punctuated result. But this was not proof
The morphological differences being used to split the fossil species? What if it really did not mark a separate species, but was just another version of the species? A model of speciation was needed to recognize a new species and support any evidence of punctuated equilibrium.
Several biological tests were performed and then he performed a test in genetics. Using a test of protein electrophoresis, he extracted enzymes and analyzed each of the eight morphologically defined species. In every case, the specimen from each species had very similar enzymes. This indicated they belonged to the same genetically related species. Cheetham had passed the fossil species test. His conclusion was that morphology still seems to say how evolution occurred(http://science.jrank.org/pages/5591/punctuated-Equilibrium.html)(Kerr 1995:1421).
Would you agree or disagree with this? Why?
Many paleontologists still say that many of these studies have their weaknesses. There is overwhelming evidence that speciation is sometimes gradual and sometimes punctuated. It is very complicated, and until there is more proof, I think I would prefer to stick to the middle ground.
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