Concepts of Evolution and DNA in Biology

Concepts of Evolution and DNA in Biology Because the fossil record did not exhibit Darwins predicted slow and gradual evolution with transitional forms, some paleontologists sought to find a theory of evolution where, changes in populations might occur too rapidly to leave many transitional fossils (see Figure from Gould and Eldredge 1977 . In 1972, Gould and Eldredge proposed the theory of punctuated equilibrium where most evolution takes place in small populations over relatively rapid geological time periods. By reducing the numerical size of the transitional population and the number of years for which it exists, punctuated equilibrium greatly limits the number of organisms bearing transitional characteristics. Since many organisms are not fossilized, this increases the likelihood that transitional forms would not be fossilized. One strength of this theory is that Gould and Eldredge claim it is predicted by population genetics. But what are the implications of punctuated equilibrium? Under punctuated equilibrium, species usually change little as, gradual change is not the normal state of a species. Large populations may experience, minor adaptive modifications of fluctuating effect through time but will rarely transform in toto to something fundamentally new. This is called stasis. But small peripheral populations may allow for more change at a quicker rate. Gould argued that most macroevolutionary change takes place in such populations during speciation such that there is insufficient time for the transitional forms to be fossilized: Speciation, the process of macroevolution, is a process of branching. And this branching â‚ ¬Ã‚ ¦ is so rapid in geological translation (thousands of years at most compared with millions for the duration of most fossil species) that its results should generally lie on a bedding plane, not through the thick sedimentary sequence of a long hillslope. What is meant by phylogeny? Give an account on phylogeny of humans. Ans- The context of evolutionary biology is phylogeny, the connections between all groups of organisms as understood by ancestor/descendant relationships. Not only is phylogeny important for understanding paleontology, but paleontology in turn contributes to phylogeny. Many groups of organisms are now extinct, and without their fossils we would not have as clear a picture of how modern life is interrelated. We express the relationships among groups of organisms through diagrams called cladograms, which are like genealogies of species. Phylogenetics, the science of phylogeny, is one part of the larger field of systematics, which also includes taxonomy. Taxonomy is the science of naming and classifying the diversity of organisms. In humans- it is used to the transfer of genes. In general, organisms can inherit genes in two ways: vertical gene transfer and horizontal gene transfer. Vertical gene transfer is the passage of genes from parent to offspring, and horizontal gene transfer or lateral gene transfer occurs when genes jump between unrelated organisms, a common phenomenon in prokaryotes. Horizontal gene transfer has complicated the determination of phylogenies of organisms, and inconsistencies in phylogeny have been reported among specific groups of organisms depending on the genes used to construct evolutionary trees. Carl Woese came up with the three-domain theory of life (eubacteria, archaea and eukaryotes) based on his discovery that the genes encoding ribosomal RNA are ancient and distributed over all lineages of life with little or no horizontal gene transfer. Therefore, rRNAs are commonly recommended as molecular clocks for reconstructing phylogenies. This has been particularly useful for the phylogeny of microorganisms, to which the species concept does not apply and which are too morphologically simple to be classified based on phenotypic traits. DNA is genetic material. Describe two classical experiments to support this statement. Ans- Clarification came during the First World War. During the war, hundreds of thousands of servicemen died from pneumonia, a lung infection caused by the baceterium Streptococcus pneumoniae. In the early 1920s, a young British army medical officer named Frederick Griffith began studying Streptococcus pneumoniae in his laboratory in the hopes of developing a vaccine against it. As so often happens in scientific research, Griffith never found what he was looking for (there is still no vaccine for pneumonia), but instead, he made one of the most important discoveries in the field of biology: a phenomenon he called transformation. Dr. Griffith had isolated two strains of S. pneumoniae, one of which was pathogenic (meaning it causes sickness or death, in this case, pneumonia), and one which was innocuous or harmless. The pathogenic strain looked smooth under a microscope due to a protective coat surrounding the bacteria and so he named this strain S, for smooth. The harmless strain of S. pneumoniae lacked the protective coat and appeared rough under a microscope, so he named it R, for rough . Dr. Griffith observed that if he injected some of the S strain of S. pneumoniae into mice, they would get sick with the symptoms of pneumonia and die, while mice injected with the R strain did not become sick. Next, Griffith noticed that if he applied to the S strain of bacteria, then injected them into mice, the mice would no longer get sick and die. He thus hypothesized that excessive heat kills the bacteria, something that other scientists, including Louis Pasteur, had already shown with other types of bacteria. However, Dr. Griffith didnt stop there he decided to try something: he mixed living R bacteria (which are not pathogenic) with heat-killed S bacteria, then he injected the mixture into mice. Surprisingly, the mice got pneumonia infections and eventually died (Figure 3). Dr. Griffith examined samples from these sick mice and saw living S bacteria. This meant that either the S bacteria came back to life, an unlikely scenario, or the live R strain was somehow transformed into the S strain. Thus, after repeating this experiment many times, Dr. Griffith named this phenomenon transformation. This discovery was significant because it showed that organisms can somehow be genetically re-programmed into a slightly different version of themselves. One strain of bacteria, in this case the R strain of S. pneumoniae, can be changed into something else, presumably because of the transfer of genetic material from a donor, in this case the heat-killed S strain. Scientists around the world began repeating this experiment, but in slightly different ways, trying to discover exactly what was happening. It became clear that, when the S bacteria are killed by heat, they break open and many substances are released. Something in this mixture can be absorbed by living bacteria, leading to a genetic transformation. But because the mixture contains protein, RNA, DNA, lipids, and carbohydrates, the question remained which molecule is the transforming agent? This question was examined in several ways, most famously by three scientists working at The Rockefeller Institute (now Rockefeller University) in New York: Oswald Avery, Colin MacLeod, and Maclyn McCarty. These scientists did almost exactly what Griffith did in his experiments but with the following changes. First, after heat-killing the S strain of bacteria, the mixture was separated into six test tubes. Thus, each of the test tubes would contain the unknown transforming agent. A different enzyme was then added to each tube except one the control which received nothing. To the other five tubes, one of the following enzymes was added: RNase, an enzyme that destroys RNA; protease, an enzyme that destroys protein; DNase, an enzyme that destroys DNA; lipase, an enzyme that destroys lipids; or a combination of enzymes that break down carbohydrates. The theory behind this experiment was that if the transforming agent was, for example, protein the transforming agent would be destroyed in the test tube containing protease, but not the others. Thus, whatever the transforming agents was, the liquid in one of the tubes would no longer be able to transform the S. pneumonia strains. When they did this, the result was both dramatic and clear. The liquid from the tubes that received RNase, protease, lipase, and the carbohydrate-digesting enzymes was still able to transform the R strain of pneumonia into the S strain. However, the liquid that was treated with DNase completely lost the ability to transform the bacteria . Thus, it was apparent that the transforming agent in the liquid was DNA. To further demonstrate this, the scientists took liquid extracted from heat-killed S. pneumoniae (S strain) and subjected it to extensive preparation and purification, isolating only the pure DNA from the mixture. This pure DNA was also able to transform the R strain into the S strain and generate pathogenic S. pneumoniae. These results provided powerful evidence that DNA, and not protein, was actually the genetic material inside of living cells. PART-B Do the two strands of DNA duplex carry the same genetic information? Explain. Ans:- No,the two strands of dna duplex carry different information ,because  complementary  base pairs  binding to form a  double helix.The two chains are wound round each other and linked together by hydrogen bonds between specific complementary bases to form a spiral ladder-shaped moleculeThe stabilization of  duplex  (double-stranded) DNA is also dependent on base stacking. The planar, rigid bases stack on top of one another, much like a stack of coins. Since the two purine.pyrimidine pairs (A.T and C.G) have the same width, the bases stack in a rather uniform fashion. Stacking near the center of the helix affords protection from chemical and environmental attack. Both hydrophobic interactions andvan der Waals forces  hold bases together in stacking interactions. About half the stability of the DNA helix comes from hydrogen bonding, while base stacking provides much of the rest. What is the difference between Z and B- DNAs? ANS:- Z-DNA  is one of the many possible double helical structures of  DNA. It is a left-handed double helical structure in which the double helix winds to the left in a zig-zag pattern. alternating  purine-pyrimidine  sequence (especially poly(dGC)2), negative  DNA supercoiling  or high salt and some  cations  (all at physiological temperature, 37 °C, and pH 7.3-7.4). Z-DNA can form a junction (called a B-to-Z junction box) in a structure which involves the extrusion of a base pair.  The Z-DNA conformation has been difficult to study because it does not exist as a stable feature of the double helix. Instead, it is a transient structure that is occasionally induced by biological activity and then quickly disappears. B-DNA It is an antiparallel double helix.It is a right-handed helix. The base-pairs are perpendicular to the axis of the helix. (Actually, they are very slightly tilted at an angle of 4 degrees)The axis of the helix passes through the centre of the base pairs.Each base pair is rotated by 36 degrees from the adjacent base pair.The base-pairs are stacked 0.34 nm apart from one another.The double helix repeats every 3.4 nm, i.e. the pitch of the double helix is 3.4 nm.B-DNA has two distinct grooves: a MAJOR groove; and, a MINOR groove. These grooves form as a consequence of the fact that the beta-glycosidic bonds of the two bases in each base pair are attached on the same edge. However, because the axis of the helix passes through the centre of the base pairs, both grooves are similar in depth. 6. What is the role of RNA in DNA replication? ANS:- RNA WAS NEED TO INTIATE THE TRANSCRIPTION PROCESS.   On the lagging strand, primase builds an RNA primer in short bursts. DNA polymerase is then able to use the free 3 OH group on the RNA primer to synthesize DNA in the 5 † Ã¢â‚¬â„¢ 3 direction. The RNA fragments are then removed (different mechanisms are used in eukaryotes and prokaryotes) and new deoxyribonucleotides are added to fill the gaps where the RNA was present. DNA ligase is then able to ligate the deoxyribonucleotides together, completing the synthesis of the lagging strand. This rna primer was a short strand of RNA that is synthesized along single-stranded DNA during replication, initiating DNA polymerase-catalyzed synthesis of the complementarystrand.  

Alzheimers Disease Essay -- Alzheimers Disease Essays

Alzheimer's Disease Alzheimer ¡Ã‚ ¦s disease is a slow, progressive, and degenerative disease of the brain. This disease is marked by a gradual loss of memory and other cognitive functions. "Alzheimer's Disease is also known as the most common cause of dementia--a general term referring to the loss of memory and the ability to think, reason, function, and behave properly" (Medina,1999). It primarily affects adults in their 60's or older and eventually destroys a person's ability to perform simple, routine tasks or even to care for themselves. Statistics show that "as many as 10 percent of all people 65 years of age and older have Alzheimer's," and that approximately "50 percent of all people 85 or older also have the disease" (WebMD, n.d.). Originally it was thought to be a rare condition affecting only young people, and was referred to as pre-senile dementia. Today late-onset Alzheimer ¡Ã‚ ¦s disease is recognized as the most common cause of the loss of mental function in those aged 65 and over. "Alzheimer ¡Ã‚ ¦s in people in their 30s, 40s, and 50s, called early-onset Alzheimer ¡Ã‚ ¦s disease, occurs much less frequently, accounting for less than 10 percent of the estimated 4 million Alzheimer ¡Ã‚ ¦s cases in the United States" (Encarta, 2004). Alzheimer's disease advances in stages, progressing from mild absentmindedness and cognitive impairment to widespread loss of mental abilities. In advanced Alzheimer's, people become dependent on others for every aspect of their care. The most common cause of death among Alzheimer's patients is infection. Even though scientists are still learning about Alzheimer ¡Ã‚ ¦s, there is no cure. Alzheimer's disease is named after Dr. Alois Alzheimer, a German doctor. "In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps (now called amyliod plaques) and tangled bundles of fibers (now called neurofibrillary tangles) within the brain"(ADEAR, 2004). Scientists have found that tangles and plaques cause the neurons in the brains of Alzheimer ¡Ã‚ ¦s patients to shrink and eventually die. They start in the memory and language centers and finally invade throughout the brain. &qu... ... former president Ronald Reagan was diagnosed with disease, it has been a major news headline ever since. There are thousands of organizations and webpage ¡Ã‚ ¦s on the internet that are filled with valuable information helping the public be aware of this disease, what the signs are, and where to go for help. With our baby-boomers aging, the disease is sure to emerge more in the next couple of years. Alzheimer ¡Ã‚ ¦s disease has touched many people since its discovery by Alois Alzheimer. Its effects on the brain cause its victims to lose some, if not most of their memory. This causes the patient to forget things such as who and where they are, who their relatives are, how to get home, or even when or how to eat. It is a personal tragedy for the patient as well as for those whom love and bear the burden of caring for them. Alzheimer ¡Ã‚ ¦s disease is a slow, progressive disease with no known cure. The treatment for Alzheimer's is still in the early stages but there are many drug treatments available which help slow its progression, and help with cognitive functions. As our population ages, Alzheimer ¡Ã‚ ¦s is only a tragedy that will affect more and more people.

Odysseus Essay

Will Rodgers, an American humorist and social commentator, once remarked that â€Å"Being a hero is about the shortest lived profession on earth† (atd. in carnival of wit 222). While this may be literally true, most heroes live on figuratively in the recorded stories of their exploits, and in many cases they model characteristics that can inspire readers to emulate they’re behavior. One obvious example is Homer’s Odysseus the fictional king of Ithaca whose courage, strength, and quest for immortality define him as the prototypical epic hero. His encounters with the Trojan war, the Cyclopes, the land of Aeolia with the bag of winds, a witch that accidentally turned his men to pigs and more. Odysseus manages to maintain the delicate balance between hubris and humbleness all throughout his ten year journey home from the Trojan War. This shows that he has potential in being a hero. Homer established the fact that Odysseus was willing to take help in addition to friendship from Athena when he wrote, â€Å"For I never knew the gods to show such open friendship and Pallas Athene standing by Odysseus. The meaning of courage is a quality of spirit that enables you to face danger or pain without showing fear, and that’s where Odysseus comes in. Odysseus has been through so much just to get back home to his family. From being in the arms of his loving wife to risking his life at war and the sea adventures with his men. Odysseus is faithful to those whom he loves and is determined to return to his home of Ithaca. As he was on the island with Calypso and she asked him to stay with her, he responded to Calypso by stating, â€Å"Every day I long to travel home and see my day of coming.

Political Globalization Essay

Traditionally, globalization is equated with modern economic development. Modern economic development is the institutionalization of capitalist structures which aimed to create the so-called â€Å"uniform world market. † However, in recent decades however, social theorists were able to point two fundamental political transformations. The first transformation involved the development of nation-states – one of the requisites of globalization (modern political institutions are necessary to achieve economic development – in the rubric of modern economic theory). The second transformation involved the end of ideological battle between Communism and Western democracy. In the second transformation, political globalization was manifested. After the Second World War, the world was divided into two camps: the Eastern Communist bloc and the West (known as the Cold War). Many developing countries – those in the Third World – became pawns of the United States and the Soviet Union. In 1990, the Soviet Union disintegrated, ending the Cold War. Thus, Western democracy became the â€Å"norm† of political development in many countries. Many countries adopted Western type political institutions, in the hope of making democracy more participative (Held and McGrew, 2007). Corollary to this was the development of the so-called â€Å"intergovernmental institutions. † These institutions linked political power and geography. For example, the International Criminal Court was established to address specified crimes like genocide, crimes against humanity, and war crimes. The court was involved in highly controversial cases like the war in Serbia. By exercising its interstate authority, the court was able to affirm its democratic obligation. Not only was the internal political structure of the state determined, its external boundary was also conditioned. Here we can juxtapose that political globalization occurred, Western type and under the guidance of the United States. The United States though acted discouraged some countries to agree in the proposed amendment to the charter of the International Criminal Court. The United States feared a sudden change of political fortunes of aspiring nations like China and the Russian Federation. The uniformization of legal norms would severely hamper the United States in â€Å"forcing† countries economic and political manifestations or favors. Reference Held, David and Anthony McGrew. 2007. Globalization. Retrieved on January 7, 2007 from http://www. polity. co. uk/global/globalization-oxford. asp.

Recommendation Brief for an Internal Accountant

Recommendation Brief for an Internal Accountant Recommendation Brief for an Internal Accountant A client has an out-of-control system that is in need of change to get it back into control. Internal controls are an important part of a company. The role of internal controls is to keep mistakes from occurring as much as possible. It also aids in preventing individuals from being dishonest. The system the client is using is out-of-control, and it is highly recommended that the company hire an internal accountant. The internal can provide information to managers to limit any problems and audit the system internally.Implementing internal audits will help build credibility within the company and keep violations from occurring that would violate laws and regulations. An internal auditor would work with management and owners to analyze important areas of the company’s performance. These areas that would be analyzed would include assets, accuracy of financial information, and ensuring t hat government and industry standards and regulations are being followed. Another point that the internal auditor would confirm is that the policies and procedures are aligned with the company’s goals.An internal auditor would add security and be an asset to the company. The first step an internal auditor would initiate would develop a plan to evaluate the current control system that is in place. Any deficiencies found would be documented and evaluated for improvement. The deficiencies would need to be corrected if possible. At the completion of the audit from the internal auditor a written recommendation explaining the control system and what needs to be done to correct the deficiencies would be given to the management of the company.There are positives in hiring an internal accountant for a company that has a system out-of-control. The first positive is the ability to minimize or extinguish any deficiencies before there are long- term effects. The second positives is the co ntrol system would be improved and help in the function of the company so that goals can be met more efficiently. A third positive is there would be a savings in money. There would no longer be a need to hire an outsider to do what an internal auditor can do. The individual hired would be knowledgeable about how the company is operated and its goals.They would also have access to information about the company that others may not have access to. The internal auditor would be on staff to do evaluations on a continual basis and be able to assist management and solve problems as issues may arise. When looking to hire an internal accountant there are some requirements or qualification that the individual needs to possess. One requirement or qualification the applicant should have is the proper education and licensing that would be appropriate for the job of internal accountant.Another area that would be important is have is experience. For the applicant to have experience in how to handl e certain situations or already have ideas of what works and does not work is important. The experience can be a time saver in solving problems with the current system. A third skill that would be an advantage in an applicant would include being knowledgeable and experienced in report writing skills. The last are to look at for a possible candidate is person characteristics.These characteristics would include being ethical, observant, self-reliant, confident, trustworthy, perceptive, and open-minded. It is important to hire an internal accountant as soon as possible because the company’s current system is already out-of-control. Hiring someone with experience would be beneficial and an asset to an already failing system. A good working relationship between the internal auditor and management is vital to the company. Having a good working relationship will help in communicating the needs and goals of the company.A recommendation of hiring a well qualified internal accountant i s vital to the success of the company. References FDIC: Federal Deposit Insurance Corporation. (n. d. ). FDIC: Federal Deposit Insurance Corporation. Retrieved April 8, 2013, from http://www. fdic. gov Audit Process. (n. d. ). University Audit Office. Retrieved April 8, 2013, from http://www. audit. cornell. edu/audit. html Welcome to NewAccountantUSA. com. (n. d. ). Welcome to NewAccountantUSA. com. Retrieved April 8, 2013, from http://www. newaccountantusa. com

Vision of the type of organization that will be needed in the future Essay

Vision of the type of organization that will be needed in the future - Essay Example This paper will describe this kind of organization considering that people as a product and the notion of talent in relation to the workforce as the greatest resource and asset of the organization. It is evident from studies that having the best people in an organization are not enough. The human resource practices are also vital in developing a visionary organization because it drives the operations of the business and exactly how it will be done. Hence the paper will also highlight the good human resource practices that the organization should employ. This is what makes the vision of the organization that will be needed in the future. A good organization begins from the top and works its operations down. An ideal organization that will be needed in future should have a strong and effective management that is aware of its mission and the mechanism of getting there. The management will composed of great and talented leaders who are ready for any impediments and obstacles that can com e there way and still be able to lead others in spite of the differences in opinions and personalities. The organization will have a united workforce with respect to their superiors, educated, and enjoys their duties in the organization. As a leader, I will hold a managerial position in such organization to drive the vision of the organization using my leadership skills and talents to unite the best people for the accomplishment of the vision (Lawler, 1998). The mission statement of the organization that will be needed in future is one that let people working in the organization know what the organization does, such vision statement has a loftier goal: it should showcase how the organization views the future. The vision of that particular organization will describe what the success of the organization would look like; the highest bar the organization always endeavor for. The organization will have both an ambitious and realistic vision statement, in other words, the vision statement should challenge the staff of the organization without overpowering them. This will ensure that performance benchmarks are created along with organizational objectives that are achievable (Barney, 2006). In the future, organizations that will be needed are those whose vision statements answers questions like â€Å"What would a world that do not need our kind of organization look like?† and â€Å"What would a perfect organization in the world look like?† such are the questions that drive change in the organization. That can only be achieved if the best people in the organization are united and work together as a team with a common goal. This type of vision unites and motivates people as a reminder that a lot of work is still pending unaccomplished. As the leader of the organization, I will use my talent to make decision on what makes sense of our organization. Occasionally, there is no particular vision statement that is intrinsically better than the other. That is why as a manager and a leader, one should be able to ascertain that which make the most sense to the organization, and that is what makes an organization exemplary. An exemplary organization, one that will be needed in the future and one organization I will be in and serve as a manger, must have a shared and an inspiring mission at its

Application essay Example | Topics and Well Written Essays - 500 words

Application - Essay Example Studying at a MBA informs an individual of the basic things one should learn on business administration and all the other aspects related to it and also extends its affects to the improvements or updated knowledge of the course. The basic concepts of business will thus be as valuable as any other information in this endeavor as much as the strategies are. What would be most challenging and interesting in this study probably might be the opportunity for students to work in the field and experience the reality and not just learn the theories. Personally, this is one of the best means for me to learn the loops and turns of the business because we come to encounter and get in contact not only with clients and business people but also learn what they have learned in their work. I understand that studying in the MBA is greatly demanding because of the requirements to the completion of the course but I believe all the efforts, time and sacrifices spent in this path will all pay well in the end. Programs in the Masters degree sharpen a person’s leadership skills which is most essential for the individual to succeed in his chosen career.