Physico-Chemical Structure or Bonding Essay Example for Free

Physico-Chemical Structure or Bonding Essay Hydrogen bond is one of the most essential concepts in supramolecular chemistry or molecular sociology. It has significant ramifications on molecular biology and materials science. The term and concept ‘hydrogen bond’ has only emerged after 1930; however the general notion of weak but specific interaction that involves hydrides is much older (Webmaster 2005). Hydrogen bond refers to the attractive force between the hydrogen that has attached to an electronegative atom of a molecule and an electronegative atom of an unlike molecule. It is a special case of dipole forces wherein the electronegative atom is usually an oxygen, nitrogen or fluorine—elements that have a partial negative charge, except for hydrogen which possesses a partial positive side (Ophardt c. 2003). Hydrogen bonding happens when two electronegative atoms, for instance nitrogen and oxygen, interact with the same hydrogen. Normally, the hydrogen is covalently attached to an atom which is referred as the donor. But it interacts electrostatically with the other, known as acceptor. The interaction is primarily because of the dipole amid the electronegative atoms and proton (Day 1996). It is the strongest molecular force and passes on some strange properties to a myriad of substances namely water, proteins and nucleotides (Structure and Bonding: The Hydrogen Bond n. d. ). Hydrogen bond is one of the most important components of biological life. If there is no hydrogen bond, there will be no life because it holds the double helix of deoxyribonucleic acid (DNA) together (Emsley 2000). Hydrogen forms and structures covalent bonds with other molecules to produce and make molecules that are stable than the free atoms. The electron of the hydrogen is shared between the hydrogen and the atom to which it is bonded. The other electron from the bonded atom is also shared between the two (The Structure of DNA n. d. ). It is done through charge attractions. If hydrogen is bonded to oxygen or nitrogen, it evolves to be slightly positive charged. That fact allows the hydrogen bond to attract a center of negative charge on another molecule—it can be another oxygen or another nitrogen atom. Thus the hydrogen bond is written such as O-H=N (= signifies hydrogen bond). There are O-H=O or N-H=O and N-H=N—it is the weakest bond (Emsley 2000). That is the effect of hydrogen bonds on DNA. On the other hand, there is a study that has been conducted by Eric Kool, a professor of Chemistry from the University of Rochester, wherein a finding has been implied that â€Å"hydrogen bonds are not the key to DNA pairing after all† (Bradt 1997). The study suggests that it is more possible that the distinguishing and distinct shapes and sizes of each of the four DNA bases strengthen and suggest the 99. 9 percent accuracy of DNA replication. It has been illustrated like a space in a jigsaw puzzle wherein that space in the puzzle can only be filled by a piece that matches the shape of the space. That analogy means that there is only one base capable of squeezing into a DNA strand on its opposite given partner (Bradt 1997). According to Myron Goodman, a biologist and DNA expert from the University of Southern California, â€Å"the apparently inescapable conclusion is that hydrogen bonds (H-bonds) are not absolutely required,† this means that the results give a momentum and impetus to consider the role that the H-bonds play in stabilizing the DNA and enhancing the fidelity of DNA polymerase (Bradt 1997). Furthermore, there are still a number of factors that are responsible for the stability of the DNA double helix structure. Hydrogen bond is just among them. Although the hydrogen bond is weak, the millions of H-bonds showcase an extremely strong force that enables and keeps the DNA strand together (Rafael B. 2009). List of References Bradt, S. (1997) â€Å"Study: Hydrogen Bonds Aren’t Key to DNA Pairing After All. † Bio-Medicine [online] available from http://news. bio-medicine. org/biology-news-2/Study-3A-Hydrogen-Bonds-Arent-Key-To-DNA-Pairing-After-All-15262-1/ [13 February 2009] Day, A. (1996). â€Å"Hydrogen Bonds. † Birkbeck: University of London [online] available from http://www. cryst. bbk. ac. uk/PPS2/projects/day/TDayDiss/HBonds. html [13 February 2009] Emsley, J. (2000). â€Å"A New Way to Investigate the Hydrogen Bonds of DNA. † Science Watch [online] available from http://archive. sciencewatch. com/sept-oct2000/sw_sept-oct2000_page7. htm [13 February 2009] Ophardt, C. (c. 2003). â€Å"Intermolecular Forces: Hydrogen Bond. † El nhurst College: Virtual Chembook [online] available from http://www. elmhurst. edu/~chm/vchembook/161Ahydrogenbond. html [13 February 2009] Rafael B. (2009) â€Å"DNA Structure: Hydrogen Bonds. † Bright Hub [online] available from http://www. brighthub. com/science/genetics/articles/23384. aspx [13 February 2009] Structure and Bonding: The Hydrogen Bond. n. d. Prince Georges Community College [online] available from http://academic. pgcc. edu/~ssinex/struc_bond/hydrogen_bond. htm [13 February 2009] The Structure of DNA. n. d. Cambridge University [online] available from http://www-outreach. phy. cam. ac. uk/camphy/dna/dna11_1. htm [13 February 2009] Webmaster. (2005). â€Å"The Hydrogen Bond. † Gottingen University [online] available from http://www. hbond. de/ [13 February 2009]

Paul Bernardo :: essays research papers

Paul Bernardo The urge shot through the mans body, uncontrollable, like sharks in a feeding frenzy. He could only quench his feverish desires by carrying out unspeakable devilish acts. The victim didn't matter, no thought was given to any implications of the satanic rituals. Several times Bernardo resorted to defecating of human beings in order to satisfy his sick and abnormal urges. Paul Bernardo's lustful and diverted sexual desires sprouted from the influence of pornography. Pornography caused him to fixate on anal intercourse, and violent, dominant sex. Pornography also played a large role in his lust for younger virgins, and the ever apparent satomasifism as seen on tape. Paul Bernardo, during his teenage years became slowly infatuated with women mostly because of his obsession with porn films. At the time film was enough to feed his growing desire for kinky sex. He was content to just watch and not act out what he saw on the videos. Through the steady diet of grotesque video's he became of aware of the type of women he wanted through what he saw. He lusted a women who was submissive and eager to please. This was the beginning of his abnormal sexual behavior. One year out of high school, Paul began his journey into the world of sexual control were he dated a sixteen year old high school student. This girl perfectly fit the description of Pauls ideal in being naive and unsophisticated. Over the three and one half years Paul was with her he used her like his personal sex toy. Throughout the entire relationship he convinced her that what they were doing was acceptable behavior. An example of his acceptable behavior was wrapping a piece of twine around her neck while he sodomized her. The twine only satisfied Bernardo for a time. Later, a knife became part of his "kit." These mercenary acts were all influenced by porno films. Paul became aroused with the power to be the master in his sexual acts and he couldn't get enough. One night in October of 1993 Paul seemed to be a magnet to Karla Homoka. The minute the two met, there relationship set off like a missile. Karla suffered love at first sight, with his looks, charm and maturity she couldn't go wrong. Karla was just the type of women Bernardo desired. She was good-looking, had a great body was naive and trusting, someone he could control, dominate and use as his personal sex toy. There sex life fired into action and the two were constantly searching for new adventures. The pair began having anal sex with

Advantages and Disadvantages of Air Travelling

When we are on holiday or intend to travel abroad as a tourist, we should firstly choose the means of traveling. In my view, traveling by air is both advantages as well as disadvantages. Advantages of traveling by air plane. The biggest advantage of flying is that it is often the fastest way to get from one place to another, especially when long distances are involved. It helps us save a lot of time, so we can do more things. Secondly, I think the comfort of air traveling makes people satisfactory. When traveling by air, we can sit comfortably in an arm- chair, reading magazines or watching a free film on television. The process of making arrangements to fly can be quite convenient. A plane ticket can be purchased by telephone or on the Internet. We don’s have to cope with crowed at air port as other stations for buying tickets. Disadvantages of traveling by air plane. Apart from these advantages, however, traveling by air has its disadvantages, too. First of all, Flying is often the most expensive form of transportation, especially if reservations are not made well in advance. Some people might not be able to afford to fly on the budget airline. Then air travels have the reputation of being dangerous and even hardened travelers are intimidated by them. There are plane crashes in which the crew and passengers have died to a man. Finally, traveling by air, we can’t stop wherever we want to enjoy beautiful landscapes on our way as we do in a trip by car or boat. Sceneries seen from plane are merely vague sights. Topic 40: Forest preservation

The Practice Of Affirmative Action - Free Essay Example

Sample details Pages: 3 Words: 915 Downloads: 4 Date added: 2019/10/30 Category Society Essay Level High school Tags: Affirmative Action Essay Did you like this example? For the past 40 years, the practice of Affirmative Action and the numerous programs linked to it have been continually under scrutiny.   By definition, Affirmative Action is an action or policy favoring those who tend to suffer from discrimination, especially in relation to employment or education; in other words it is an act of positive discrimination. As an outcome of the 1960s Civil Rights Movement, these policies were put into place to even the playing field and to promote social equality for those who have been historically disadvantaged. Specifically it is aimed at minority groups and women that have been excluded from employment and the workplace. Don’t waste time! Our writers will create an original "The Practice Of Affirmative Action" essay for you Create order Today, most job and school applications ask a persons race, ethnic background, gender and veteran status and that can be directly linked to the process of Affirmative Action.   Looking back to 1965, 5% of undergraduate students, 1% of law students and 2% of medical students were African American. According to the National Center on Education Statistics, in 2007, 70% of white high school students graduated and immediately enrolled in college whereas 56% of African American graduates and 61% of hispanics. There is continuous controversy over whether this policy is inconsistent with the principle of merit and in turn is reverse discrimination. The disagreement comes from both sides of the classes. The members of the protected classes, which Affirmative Action is aimed at, argue that they are believed to be less qualified and make society look down on them for being prefrientally treated. While those non-protected members feel they are passed over in favor of less qualified, more diverse candidates. The landmark case in 1978, Regents of the University of California v. Bakke, upheld certain aspects of affirmative action while also rejecting other aspects. Specifically, the Equal Protection Clause of the 14th Amendment was violated however, using race as an admissions decision was constitutional when viewed in combination with several other admission criteria. Since that case we have continued to see more and more lawsuits against college admissions.   A more recent court case that is sure to make an impact on the view of affirmative action is SFFA vs. Harvard University. In November 2014, Students for Fair Admissions, also known as SFFA, filed a lawsuit against Harvard University, claiming that the University discriminates against Asian Americans. The aim of SFFA vs. Harvard University, is to validate that white applicants are given preferential treatment over Asian Americans. While this case isnt Affirmative Action in itself, it is focusing on whether the Civil Rights Act has been violated due to discrimination. With both parties stating they will appeal to the Supreme Court, the outcome has the potential to change affirmative action and college admissions everywhere.     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   The two parties in this case are Harvard University as the defendant and Students for Fair Admissions as the plaintiff. The defendants will include various school administrators, with the plan of calling witnesses of Harvard alumni and students from different backgrounds. The SFFA represents a group of anonymous Asian Americans previously rejected from the university. Edward Blum, leader of the Project on Fair Representation, has taken the face of this trial to protect those who wish to stay anonymous. The plaintiff is arguing that University officials have been aware of the penalty placed on Asian Americans with their personal rating and in turn is discrimination against Asian Americans. The defendant has argued that all claims are unsupported and the admissions process has been previously upheld by the Supreme Court. When applicants apply to Harvard they are assigned a personal rating based allegedly on information collected from various sources such as teacher and guidance-counselors. The four-point scale is 1. Outstanding 2. Very Strong 3. Generally positive 4. Bland or somewhat negative or immature. The evidence entered into court showed that Asian Americans in fact were scoring much lower on the personal rating and higher on academics and extracurriculars   compared to white applicants. Adam Mortara, an attorney for SFFA, argued that University officials were aware of the penalty assigned to Asian American applicants based on Reports by Harvards Office of Institutional Research. Another smoking gun against Harvard University is their use of PSAT scores to recruit high-schoolers. Admissions documents revealed that white students received recruitment letters if they scored a 1310 or higher. Asian Americans received recruitment letters if they scored a 1350 for women, or 1380 for men. Harvard argued that their goal was to reach students where Harvard was not on their radar and they were looking for students from any background from sparse country. A study of enrollment trends for three selective schools, MIT, Harvard, and Caltech has been released by the Center for Equal Opportunity. MIT and Harvard both use racial reference during the admissions process while Caltech does not. At Caltech Asian Americans make up more than 40% of seats in a class, in comparison they make up 26% at MIT and 17% at Harvard. Applicants are no less qualified at these schools than those in California and this can be directly connected with the color blind admissions process at Caltech. To continue research on preferential admissions two sociologists from Princeton, Thomas J. Espenshade and Alexandria Radford, studied eight elite schools to determine how much better Asian Americans have to perform to be competitive. The conclusion was that Asian American applicants would need to score 140 points greater than white applicants on the SAT, 270 points higher than Hispanics, and 450 points higher than black applicants.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   With all information taken into consideration SFFA has accused Harvard of racial balancing, with evidence proving that the same percentage of blacks, Hispanics, whites and Asian Americans are enrolled in each class.