On pages 191 and 192, Dr. Sharon Moalem discusses the process of aging. He notes that already, experiments are ongoing to determine how the mechanisms of aging work. Moalem continues on to discuss progeria, which is a disease that accelerates the aging process, and how progeria affects aging. Finally, Moalem writes that some scientists have been able to reverse the breakdown of aging cells, which can effectively lead to the slowing of the aging process in humans.
However, this slowdown of aging is not always beneficial to humans. Referring to the Campbell text, Moalem's book, and course notes, present evidence demonstrating ways that aging can actually be beneficial not just to an individual, but a species as a whole. After answering this question, discuss briefly why you believe scientists are so intent on slowing down the aging process. Do not simply discuss progeria; rather, provide other examples as well. Connect your responses primarily to Big Idea 3, the idea that living systems store, retrieve, transmit, and respond to information essential to life processes; however, do not forget to relate answers to the process of evolution as well.
Jeeho Lee (jelee4@students.d125.org)
yolo
ReplyDeletePart 1
ReplyDeleteAging has two main benefits, one for the individual and one for the species as a whole. For the individual, Dr. Moalem states that "Many scientists believe cancer prevention is the "reason" cells have evolved with a limit on the number of times they can reproduce" (189). The main fighters against cancer for the individual are telomeres and the Hayflick limit. Each chromosome has telomeres at the end that aren't specifically replicated to help make proteins or to regulate gene expression. The function of the telomeres is to serve as a counter for replication and to act as a buffer for the vital information in the chromosome. As cells reproduce, telomeres are shortened, so the DNA inside the chromosome is safe from the deletion from replication. If a cell becomes cancerous and starts to reproduce rapidly, the Hayflick limit and the telomeres make it so that the cell can only replicate 50-60 times before the inner DNA deteriorating and becoming useless. This limit makes it so that the cancerous cells die out rather than grow endlessly. So overall, the general deterioration of the cells, or the process of aging, is a way for the individual to fight against cancer when all other methods fail. The idea of telomeres and the Hayflick limit relates to Big Idea 2, biological systems utilize free energy and molecular building blocks to grow, reproduce, and to maintain dynamic homeostasis, because telomeres are basically additional building blocks placed at the end of chromosomes to make sure the inner structure isn't damaged. Additionally, telomeres and the Hayflick limit prevent any one cell from harming the body by providing a way for a cell to die if there are problems with it, which maintains homeostasis by allowing the body to function as it normally does instead of being harmed.
For a species as a whole, aging drives the process of evolution. The concept of evolution relies on the idea that favorable mutations and variations in a population become more common over a long period of time in a population due to selection pressures. Since the genetic make up of an organism can't change in an individual's lifetime, (only the genes expressed can with the help of epigenetics, and even then, the traits of an individual organism can't change drastically) the favorable traits have to be passed onto the offspring of the individual. This allows for the constant improvement of a species through natural selection and possibly even speciation over a long enough time. If the old individuals of a population didn't age, then their inferior genetic material could survive and go on to reproduce. This would be less beneficial to the species as a whole because the offspring would not have as many favorable traits as the offspring of the newer generation. Aging helps to get rid of the organisms that are less fit to survive in an environment, and it helps the species as a whole select for more favorable variations and progress as a whole. Dr. Moalem says that, "Biogenic obsolescence- that is to say, aging- might accomplish two similar ends. First, by clearing out older models, aging makes room for new models, which is exactly what creates the room for change- for evolution. Second, aging can protect the group by eliminating individuals that have become laden with parasites, preventing them from infecting the next generation. Sex and reproduction, in turn, are the way a species gets upgraded" (191). Overall, aging relates to Big Idea 1, the process of evolution drives the diversity and unity of life, because it is the way in which room is made for new variations in a population.
Tony Massat amassat4@students.d125.org
Part 2
ReplyDeleteThere are many reasons why scientists are so intent on slowing down the aging process. The main reasons are because everyone wants to be immortal, and to prevent age related diseases from killing loved ones. That is more of a moral issue though, how scientists are getting this done is another issue altogether. For progeria specifically, which causes rapid aging in children due to a lack of production of lamin A, a protein that provides structural support for the nuclear membrane causing rapid cell deterioration, researches have been trying to find a way to either supplement lamin A, or inhibit the progerin protein which damages cell function. According to progeriaresearch.org, "Lonafarnib, a type of farnesyltransferase inhibitor (FTI) originally developed to treat cancer, has proven effective for Progeria" (http://www.progeriaresearch.org/first-ever-progeria-treatment.html). This drug helps to inhibit the progerin protein from damaging infected cells, and has caused children to gain weight and have improved bone structure. This connects to Big Idea 3, living systems store, retrieve, transmit, and respond to information essential to life processes, because the Lonafarnib responds to the progerin attacking the body's cells and reacts by inhibiting the progerin, allowing the cells to behave normally in the living system of the human. Scientists have been working with progeria and in general trying to prevent diseases related to aging once and for all.
Besides for progeria, Scientists have been trying to extend life by experimenting with worms. Scientists activated life extension in the roundworm C. elegans by changing the metabolism of certain worms of the species. "To make this discovery, scientists compared one class of long-lived C. elegans, called the Mit mutants (which have disrupted mitochondrial electron transport chain functionality), with non-mutant wild type C. elegans. Their comparison showed significant metabolism changes, suggesting that their cellular engines had been reconfigured to run on new fuels and to make new waste products, leading to increased lifespans" (http://www.sciencedaily.com/releases/2010/12/101201102603.htm). By changing the worms metabolisms, these scientists were able to manipulate the aging process, allowing the worms to live longer. Overall, scientists want to restrict aging to make it possible to live longer and to prevent diseases from occurring, and they are definitely making progress to making this hope a reality.
Tony Massat amassat4@students.d125.org