Enzyme Structure and Functions:

ENZYME STRUCTURE AND FUNCTIONS: Enzymes are biological catalysts. They increase the rate of reactions by a factor of between 106 to 1012 times, allowing the chemical reactions that make life possible to take place at normal temperatures Definition of enzyme: A protein with catalytic properties due to its power of specific activation is defined as an enzyme. STRUCTURE Enzymes are proteins their function depends on its complexity. The reaction takes place in a small part of the enzyme called the active site, while the rest of the protein acts as â€Å"scaffolding†.The shape and the chemical environment inside the active site permits a chemical reaction to proceed more easily Many enzymes need cofactors (or coenzymes) to work properly. Tightly bound cofactors are called prosthetic groups Cofactors that are bound and released easily are called coenzymes These can be metal ions (such as Fe2+, Mg2+, Cu2+) or organic molecules (such as haem, biotin, FAD, NAD or coenzyme A). Many of t hese are derived from dietary vitamins, which is why they are so important. The complete active enzyme with its cofactor is called a holoenzyme, while just the protein part without its cofactor is called the apoenzyme.HW DOES AN ENZYME WORK? 1) REACTION MECHANISM 2) MOLECULAR GEOMETRY REACTION MECHANISM: In any chemical reaction, a substrate (S) is converted into a product (P) In an enzyme-catalysed reaction, the substrate first binds to the active site of the enzyme to form an enzyme-substrate (ES) complex, then the substrate is converted into product whilst attached to the enzyme, and finally the product is released, thus allowing the enzyme to start all over again An example is the action of the enzyme sucrase hydrolysing sucrose into glucose and fructose.MOLECULAR GEOMETRY The substrate molecule is complementary in shape to that of the active site. It was thought that the substrate exactly fitted into the active site of the enzyme molecule like a key fitting into a lock (the now discredited ‘lock and key’ theory). This explains enzyme specificity This explains the loss of activity when enzymes denature The Induced Fit Hypothesis  : * Some proteins can change their shape (conformation) When a substrate combines with an enzyme, it induces a change in the enzyme’s conformation * The active site is then moulded into a precise conformation * Making the chemical environment suitable for the reaction * The bonds of the substrate are stretched to make the reaction easier (lowers activation energy) ENERGY CHANGES  : Energy needed for initial reaction is known as ACTIVATION ENERGY. The larger the activation energy is, the slower the reaction will be.This is because only a few substrate molecules will have sufficient energy to overcome the activation energy barrier. Enzymes reduce the activation energy of a reaction so that the kinetic energy of most molecules exceeds the activation energy required and so they can react. Factors affecting Enzy mes substrate concentration pH temperature enzyme concentration inhibitors SUBSTARTE CONCENTRATION The rate of an enzyme-catalysed reaction is also affected by substrate concentration.As the substrate concentration increases, the rate increases because more substrate molecules can collide with active sites, so more enzyme-substrate complexes form. At higher concentrations the enzyme molecules become saturated with substrate, and there are few free active sites, so adding more substrate doesn't make much difference The maximum rate at infinite substrate concentration is called vmax, and the substrate concentration that gives a rate of half vmax is called KM.These quantities are useful for characterising an enzyme. A good enzyme has a high vmax and a low KM. pH Enzymes have an optimum pH at which they work fastest. For most enzymes this is about pH 7-8 (normal body pH), but a few enzymes can work at extreme pH. The pH affects the charge of the amino acids at the active site, so the pr operties of the active site change and the substrate can no longer bind. TEMPERATURE: Enzymes have an optimum temperature at which they work fastest.For mammalian enzymes this is about 40 °C. Up to the optimum temperature the rate increases geometrically with temperature. Above the optimum temperature the rate decreases as more of the enzyme molecules denature. The thermal energy breaks the hydrogen bonds holding the secondary and tertiary structure of the enzyme together, so the enzyme loses its shape Q10 (the temperature coefficient) = the increase in reaction rate with a 10 °C rise in temperature. ENZYME CONCENTRATIONAs the enzyme concentration increases the rate of the reaction also increases, because there are more enzyme molecules (and so more active sites), available to catalyse the reaction therefore more enzyme-substrate complexes form INHIBITORS Inhibitors inhibit the activity of enzymes, reducing the rate of their reactions. 2 TYPES: Competitive and non competitive CO MPETITIVE: A competitive inhibitor molecule has a similar structure to the substrate molecule, and so it can fit into the active site of the enzyme. It therefore competes with the substrate for the active site, so the reaction is slower.Increasing the concentration of substrate restores the reaction rate and the inhibition is usually temporary and reversible. NON COMPETITIVE: A non-competitive inhibitor molecule is quite different in structure from the substrate and does not fit into the active site. It binds to another part of the enzyme molecule, changing the shape of the whole enzyme, including the active site, so that it can no longer bind substrate molecules. Non-competitive inhibitors therefore simply reduce the amount of active enzyme.

Final EXAM Essay Example | Topics and Well Written Essays - 1000 words

Final EXAM - Essay Example According to some individuals, the belief in the existence of human rights is just the same as believing in unicorns and witches. Despite some people questioning the existence of human rights, there is no doubt that human rights does indeed exist (Alexy 15). The answer to the burning issue of the existence of human rights is pegged on what human rights are, and as a way of definition, human rights are rights. What proves the existence of human rights is its universality? Ideally, every human being is eligible for human rights. In most cases, human right is used to put a claim on the right to life for every individual. Apart from this, this is used to denote the right for every individual to take part in the process of political-will formation, especially on the area of voting. While the right to life is universal, the political will formation is applied to only some parts since what might be acceptable in one location might not necessarily be acceptable in another place (Rivers 178). Ideally, human rights are as old as the existence of man and their value remains cornerstone to the human race. However, the usage of this term was heightened in the mid-20th century during the struggle for the recognition of civil rights for blacks led by Martin Luther king Jr. However, for many years, individuals in the United States have been fighting for their rights especially the rights of women and children. This means that the existence of human rights is something that has been around for a long time. In most cases, the question of law and order is used to define human rights. While some people claim that the society is only guided by morality, the truth is that the presumed moral standards are nothing but an observance of the rules set down so that human rights are not violated (Rivers 179). Human rights are theoretical rights, and as abstract rights, human rights in many ways clash with without countless other civil rights. In order to ensure

Web Server Application Attacks Research Paper Example | Topics and Well Written Essays - 1250 words

Web Server Application Attacks - Research Paper Example A command injection attack refers to an attack aimed at compromising the sensitive information featured in the back end database that supports the interactive aspects of a web application. Included under this category are issues like cross-site scripting (XSS) and Structured Query Language (SQL) injection. To curb this attack, organizations need to plan and address the security matters that pertain to their web solutions during web development or planning stages. Examples of such approaches would be to hire web application developers with proper knowledge on use of more sophisticated database capabilities like stored procedures to reside in the back end database system or the concept of data objects when writing APIs to access the database system that supports the web utilities. Equally, XSS issues can be handled by employing Model Viewer Controller (MVC) frameworks like Codeignitor while developing web applications. Such frameworks have in-built capabilities to suppress the efforts of clients who try to launch XSS attacks. A precaution taken during the development or planning of a web application is worthwhile for the reason that security issues are harder to handle once a system is deployed or implemented. The third type of attack that targets web servers is interception of unencrypted information that is channeled in communication sessions that take place between the client browsers and the servers. One way to combat this problem is to use Secure Socket Layer (SSL) in web-centered communication. SSL helps in creating an encrypted link between client-server communications. In particular, the concept uses SSL certificates (typically methods like symmetric and asymmetric encryption) to transfer sensitive information like social security numbers and credit card numbers. In the diagram, the server first sends a copy that bears its asymmetric

Assignemt 4 ,investing Essay Example | Topics and Well Written Essays - 1000 words

Assignemt 4 ,investing - Essay Example The company places significant importance on innovation. This gives the company a cutting edge in comparison to its competitors. M.A.C cosmetics also defined as Makeup-Art and Cosmetics. The company was initiated by Frank Toskan and Frank Angelo in the year 1984. The concept of M.A.C was perceived initially by Frank Angelo. Toskan was a celebrated makeup artist and Angelo was the proprietor of chain of hair salon. The common interest in fashion shared by both brought the two together in creating the brand M.A.C. Angelo and Toskan realized the need of a reliable make up brand in the market. Both recognized the need of a makeup brand that was durable, creative and versatile. The makeup was mostly aimed for the makeup requirement at photo shoots. Està ©e Lauder in 1994 gained the controlling interest in MAC and the acquisition was settled in 1998. M.A.C is now one of the celebrated brands of Està ©e Lauder. In 1994 the MAC AIDS was introduced. The year before MAC was acquired by Estee Lauder Frank Angelo due to health complications passed away and Toskan also chose to exit from the company. MAC religiously don ates 100% of their selling profit from their brand Viva Glam to the MAC AIDS fund. John Demsey was appointed at the post of Group President in the year 2006. He is currently responsible for the brands M.A.C, Sean, John, La Mer, and Jo Malone, Bobbi Brown, Prescriptives under the Estee Lauder group. In the year 2005 Mr. John Demsey was appointed as Global Brand President of Estee Lauder after his appointment as the President and Managing Director of M.A.C from the year 1998. From the year 1991 till 1998 Mr. Demsey has held several positions with Estee Lauder, including the post of Senior Vice president of Sales and Education (Estee Lauder, USA & Canada). Before joining Estee Lauder Mr. Demsey worked for Revlon, Alexandra de Markoff , Lancaster cosmetics and Borghese Mr. Demsey currently also holds several executive retail positions

The Definition and Criticism of an Insanity Defense Essay - 1

The Definition and Criticism of an Insanity Defense - Essay Example Very few people plead insanity though and among those who plead it, a very minor part wins the plea. An important point here is people acquitted under insanity defense are seldom allowed to walk free. In almost all cases, the acquitted people are allowed to go to treatment centers and kept there until mental health officials determine they do not pose a danger to anyone. Criticism to insanity defense is a common phenomenon. Critics argue that some defendants misuse insanity defense, effectively faking insanity to win acquittals or less severe convictions. And often the trials involving an insanity defense get the most attention because they involve crimes that are peculiar within themselves. Nevertheless, studies suggest the overwhelming majority of defendants acquitted by reason of insanity suffer from schizophrenia or some other mental illness (Fersch, 2005). There could be several reasons for criticizing the insanity defense, including political, legal as well as humanistic. In USA, for instance, the insanity defense received harsh public criticism when, after the 1981 assassination attempt on Ronald Reagan by John Hinckley Jr., Hinckley was found not guilty by reason of insanity. Lot of people argues argued that his premeditation of the crime was undeniable proof of his sanity. Public criticism of the insanity defense has continued to grow with each high profile case. In conclusion, insanity plea is a poor excuse for serious lawbreaking, and should not ideally influence or ease the punishment. In a majority of criminal cases, especially murder trials, an insanity plea is used as a defense strategy aimed at saving guilty defendants from death penalty or serving time in prison. The accused usually pretend to be mentally ill and their lawyers use this as a way to confuse jury and influence their judgment. And then most of the accused, by reason of insanity,

Financial Research Essay Example | Topics and Well Written Essays - 3000 words

Financial Research - Essay Example Charitable fundraising is becoming more difficult and competitive. At the same time, society's need for charitable services is growing. In such a challenging environment, how can charities keep up with ever-changing legal requirements -- and still have time to raise money and carry out their charitable missions A new series of Law and Tax Guides for Charities helps show the way. The first title in the series, The Charity's Guide to Charitable Contributions, is a practical, plain-English guide to what charities need to know about the federal income tax deduction for charitable contributions. It's an essential tool for every charity. Veteran tax lawyer Pamela McAllister guides readers through the maze of federal tax laws with topics ranging from membership premiums to special event, auctions to thrift shops. Readers discover clear, step-by-step instructions for determining how much of a contribution is deductible and what to tell their donors in a wide range of everyday situations, plus valuable practical advice on maintaining positive donor relations." This article by Pamela McAllister shows the charitable ... amela McAllister shows the charitable organizations like Q note how to follow the technical requirements of the donation law by giving them important checklists, guidelines, and sample forms that surely will help charities be professional and knowledgeable, assist their donors, and avoid tax penalties it also has countless real-word examples. So this financial research on charities is shows us that our Q note school will thrive because the United Kingdom government encourages companies to give to charitable institutions like Q note. In return the donating companies will report the donations as deductions from the total gross income. This donation will then lower the total amount of business income that the company will use as basis for computing the amount of taxes the company will pay the United Kingdom government. If the donations are bigger, then the gross income deduction will also be bigger. But the United Kingdom tax law also states that there is a limit to the amount of donations that a company will give to charitable institutions like Q note. Although, this will lessen the charitable contribution amount that each charitable organization will receive from one company, the charitable organizations can spend more time looking for other companies that will be philanthropic enough to give excess funds to the Q note Sch ool. Therefore the charitable organizations and also the donor company or companies.benefits from this taxation law pertaining to charitable contributions. SOUND ENGINEERING. Since there is a big market for songs and recordings of meetings, conferences and the like, the student graduates will have a bright future in the chosen field of work as compared to the alternative of joining the inner city street gangs and live a dangerous life of

Introduction to Astronomy Essay Example for Free

Introduction to Astronomy Essay The life cycle of a star is a process that is not only beautiful but, fascinating to those fortunate ones who have the chance to study the subject. To the uneducated soul, gazing upon the night sky wondering what is out there is not a common thing. But being able to learn about what is really out there and how it became, that my friends, is truly an amazing task. One has to wonder just how we know what type of star we are looking at or at what point in the star’s life cycle the star dwells. Since the dawn of man, we have studied the stars, and until the last century, astronomers have found ways to measure four properties of stars: their luminosities, temperatures, radii, and masses. With this knowledge, they now have classified thousands of stars by plotting these stars on diagrams and charts characterized by any pair of these specific properties. A Star is Born Stellar Nursery – Nebula The proverbial birth of a star starts within a huge cloud of gas and dust known as a nebula. A nebula is approximately 21 light-years in width. When the gases and elements of the nebula start to contract due to the pull of its own gravity, it will create a protostar, which can startingly grow to roughly 60 million miles across. This is where the star begins to take shape. In order for a star to grow, it will need nuclear fusion to take place, and that requires tremendous amounts of pressure and heat. Main Sequence Stars The enormous pressure that is created compresses together elements to form more elements and to create energy. With hydrogen being the least dense and easiest to fuse, stars begin fusing hydrogen first. The side effect of this fusing of nuclei, or nuclear fusion, is the production of two positrons, two neutrinos, and the release of energy. Stars that are in the hydrogen burning process are known to be in the main sequence. Stars will spend the majority of their lifespan in the main sequence. Using the standardized classification system, astronomers find that about 90% of all stars cluster in thin bands on each the noted diagrams. Red Giant Eventually in the star’s life, the hydrogen supply in the core will begin to expire, when this happens, the sun’s core becomes unstable and will begin to contract. Consequently, the outer shell of the star, which consists mainly of hydrogen, will start to expand. During the expansion, it cools and will begin to glow red. The star now resides a red giant phase of its life cycle (Cain, 2009). Practically all stars will evolve identically up to the red giant phase, yet depending on the amount of mass a star, the next phase in the life cycle can be greatly different. Supergiants One possible evolution of extremely massive stars, although rare, is to become a supergiant. But what is a supergiant? When the radiation released by the fusion of helium into carbon it causes the red giant to expand even larger, perhaps into a star roughly 400 times the Sun’s size. The End of Days – Death of a Star White Dwarf A white dwarf, or a remnant of a star that has collapsed, are the destiny of stars like our sun. This phase in the life cycle is attained when the nuclear fuel supply is exhausted. Typically, a white dwarf can have the mass of about six-tenths the mass of our sun, but obtains size considerably smaller than that of the Earth. A white dwarf is formed when the shroud of a red giant is ejected as the core burns the last bits and pieces of its nuclear fuel. A white dwarf slowly fades into oblivion as it cools down. Supernova Possibly, exceedingly massive stars can continue to fuse heavy elements in order to produce more energy. Nevertheless, once iron is formed, it cannot be fused to make more energy. This is because iron has such a high binding energy and is thus very stable. Due to the immense gravity, the core will collapse and huge amounts of gas on the surface will blast out into space. This phase in the star’s life cycle has now become a supernova. Neutron Star Following a supernova explosion, the iron core of the star may be enormously massive, and may have an immense force of gravity. It has now become a neutron star, where the negative force, or pushing effect, between neutrons stops the contraction caused by gravity. Pulsar It is possible for a neutron star to spin rapidly following a supernova explosion. A result of this spinning, the neutron star may send out two beams of radio waves, light, and X-rays. These beams radiate in a circle as the star is spinning, and thus appears that the light from the star is pulsing intermittently. This is why it is called a Pulsar. Blackhole Yet some extremely massive supergiants, many with a mass more than four times that of our own Sun, may continue contracting until their nuclei are compacted into even more dense matter. The compacting matter forms a body so dense that it forms a black hole. A black hole is an extremely massive and dense, spectral body with a gravitational pull powerful enough to prevent the escape of light (Newman, 2002). Life as We Know It Astronomers believe Earth and all its living organisms are composed of elements formed in the interiors of stars, especially supergiants that exploded as supernovas. As astronomers across the globe scour planetary systems, both within and beyond our galaxy, in the quest to find life, they are centering their attention on each systems habitable zone. The habitable zone is where heat radiated from the star is just right to keep a planets water in liquid form (Williams Pollard, 2000), the sweet spot of the solar system.