Signal Transduction Essay Example

Signal Transduction Essay Cells are not only the â€Å"smallest units of life† but they also depict â€Å"the best machineries in the world†. Cells not only work exceptionally well within their own systems but coordinate efficiently with other cells in order to ensure their survival. Reactivity, which refers to the living thing’s ability to respond to signals from the environment; enables the organism to react to various stimuli, either behaviorally or physiologically (The Characteristics of Life). Signals come in various forms such as changes in temperature, illumination, pressure and even intercellular chemical concentration. Other signals which take subtler forms are those which signal either cell division or cell differentiation. Protective responses are also carried out by most cells whenever foreign substances intrude the organism’s body. Such feats are only possible through signaling systems which are either intracellular or intercellular (The Cell Signaling Test) and are ge nerally referred to as signal transduction pathways.Signal transduction figures in information metabolism. Information metabolism refers to the cell’s reception, processing and consequent response to information from the environment (Signal Transduction Pathways: An Introduction to Information Metabolism). At the cellular level, signal transduction refers to the movement of signals from the outside to the inside of the cell. The process through which signal transduction occurs varies depending upon the nature of chemicals and their associated receptors. Signal movement can be as simple as those which involve the receptor molecules of the acetylcholine class or can be as complex as those which involve combinations of ligand – receptor interactions and several intracellular events. In the case of simple signal transduction, signals pass in or out of the cell through receptors which are mainly composed of channels. The process is effected out by ligand interaction through the form of small ion movements. These ion movements in turn result to changes in the cell’s electrical potential and consequently, to the propagation of the said signal along the cell (Mechanisms of Signal Transduction). Complex signal transduction, as mentioned before, does not only involve ligand interactions but also several intracellular events. These events include phosphorylations induced by the enzymes tyrosine kinases and/or serine/threonine kinases. Protein phosphorylations are specifically helpful in understanding the process of gene expression since they influence, to a large extent, enzymatic activities and protein conformations (Mechanisms of Signal Transduction).Pathways of signal transduction could therefore be depicted as molecular circuits. A pathway typically begins with the transfer of information from the environment towards the cell’s internal system. Nonpolar molecules (steroid hormones such as estrogen) could easily penetrate the cell membrane and could therefore, enter the cell. Once inside the cell, these molecules bind to proteins and interact with the cell’s DNA. The consequence of this interaction is that the molecules’ directly influence gene transcription. Other molecules, such as those which are too large or too polar, are not able to pass through the cell’s membrane. The information that these molecules carry must then be transmitted to the cell’s interior through another means. Such means is accomplished through the action of a membrane – associated receptor protein. A receptor of such type has often two domains: an extracellular and an intracellular domain. The former contains a binding site to which a ligand or a signal molecule is recognized. The interaction between the receptor and ligand consequently alters the receptor’s tertiary or quaternary structure as well its intracellular domain. Though such structural changes have been effected, the small number of receptor molecules in the cell membrane limits, or to a certain extent, hinders the yielding of an appropriate response. Ligands or primary messengers therefore, carry information which is transduced into forms which can either modify or influence the cell’s biochemistry.Second messengers comprise the next step in the transduction pathway. These messengers relay information from the receptor – ligand complex through changes in their concentration. Changes in concentration amplify the signal’s effect and influence, to a large extent, intracellular signal and response.   Protein phosphorylation is another means of information transfer. Responses are elicited by the activation of enzymes such as protein kinases. These enzymes transfer phosphoryl groups from ATP to certain protein residues such as serine, tyrosine and threonine through the process of phosphorylation. cAMP-dependent protein kinase as well as other protein kinases are links that transduce changes in the fre e second messenger concentration into alterations in protein covalent structures. These changes are less transient compared to secondary – messenger concentrations but the results of such process are reversible (Signal Transduction Pathways: An Introduction to Information Metabolism).Once the signal has been initiated and has been transduced to affect other cellular processes, it is equally important that the signal is terminated effectively. Signal termination is mostly carried out by the action of protein phosphatases. Whereas protein kinases are responsible for phosphorylation (Signal Transduction Pathways: An Introduction to Information Metabolism), protein phosphatases are responsible for dephosphorylation (Protein Phosphatases).   Dephosphorylation refers to the removal of a phosphate group (Dephosphorylation). The importance of this phase in the signal transduction pathway is clearly manifested when the process goes awry. If the effects of a previous signal are sti ll in effect, the cell could not respond to new and incoming signals. Cancers and uncontrolled cell growth are often the offshoot of the failure in this phase of the pathway (Signal Transduction Pathways: An Introduction to Information Metabolism).

Real Gas Definition and Examples

Real Gas Definition and Examples A real gas is a gas that does not behave as an ideal gas due to interactions between gas molecules. A real gas is also known as a nonideal gas because the behavior of a real gas in only approximated by the ideal gas law. When Real Gases Differ From Ideal Gases Usually, its fine to use the ideal gas law to make calculations for gases. However, the approximation gives considerable error at very high pressure, near the critical point, or near the condensation point of a gas. Unlike ideal gases, a real gas is subject to: Van der Waals forcesCompressibility effectsNon-equilibrium thermodynamic effectsVariable specific heat capacityVariable composition, including molecular dissociation and other chemical reactions Real Gas Example While cool air at ordinary pressure behaves like an ideal gas, increasing its pressure or temperature increases the interactions between molecules, resulting in real gas behavior that cannot be predicted reliably using the ideal gas law. Sources Cengel, Yunus A. and Michael A. Boles (2010). Thermodynamics: An Engineering Approach (7th Ed.). McGraw-Hill. ISBN 007-352932-X.Xiang, H. W. (2005). The Corresponding-States Principle and its Practice: Thermodynamic, Transport and Surface Properties of Fluids. Elsevier. ISBN 978-0-08-045904-2.

The History of Black Women in the 1950s

The History of Black Women in the 1950s African-American women are an essential part of our collective history. The following is a chronology of events and birthdates for women involved in African-American history, from 1950-1959. 1950 Gwendolyn Brooks became the first African-American to win a Pulitzer Prize (for Annie Allen). Althea Gibson became the first African-American to play at Wimbledon. Juanita Hall became the first African-American to win a Tony Award, for playing Bloody Mary in South Pacific. January 16: Debbie Allen born (choreographer, actor, director, producer). February 2: Natalie Cole born (singer; daughter of Nat King Cole). 1951 July 15: Mary White Ovington died (social worker, reformer, NAACP founder).   Linda Browns father sued the Topeka, Kansas, school board because she had to travel by bus to a school for African-American children when she could walk to the segregated school for white children only.  This would become the  Brown v. Board of Education  landmark civil rights case. 1952 September:  Autherine Juanita Lucy and Pollie Myers applied to the University of Alabama and were accepted. Their acceptances were rescinded when the university discovered they were not white. They took the case to court, and it took three years to resolve the case. 1954 Norma Sklarek became the first African-American woman licensed as an architect. Dorothy Dandridge was the first African-Amerian woman nominated for a Best Actress Oscar, for playing the lead role in Carmen Jones. January 29: Oprah Winfrey born (first African-American woman billionaire, first African-American woman to host a nationally syndicated talk show). September 22: Shari Belafonte-Harper born (actress). May 17: In Brown v. Board of Education, Supreme Court ordered schools to desegregate with all deliberate speed - finds separate but equal public facilities to be unconstitutional. July 24: Mary Church Terrell died (activist, clubwoman). 1955 May 18: Mary McLeod Bethune died. July: Rosa Parks attended a workshop at the Highlander Folk School in Tennessee, learning effective tools for civil rights organizing. August 28: Emmett Till, 14 years old, was killed by a white mob in Mississippi after he was accused of whistling at a white woman. December 1: Rosa Parks was arrested when she refused to give up a seat and move to the rear of the bus, triggering the Montgomery bus boycott. Marian Anderson became the first African-American member of the Metropolitan Opera company. 1956 Mae Jemison born (astronaut, physician). Hundreds of women and men in Montgomery walked for miles to work rather than use the buses as part of the Montgomery Bus Boycott. A court ordered the University of Alabama to admit Autherine Juanita Lucy, who filed a lawsuit in 1952 (see above). She was admitted but was barred from dormitories and dining halls.  She enrolled on February 3 as a graduate student in library science, the first black student admitted to a white public school or university in Alabama. The university expelled her in March, claiming she had slandered the school, after riots broke out and the courts ordered the university to protect her. In 1988, the university annulled the expulsion and she returned to school, earning her M.A. degree in education in 1992. The school even named a clock tower for her, and featured her portrait in the student union honoring her initiative and courage. December 21: The Supreme Court ruled bus segregation in Montgomery, Alabama was unconstitutional. 1957 African-American students, advised by NAACP activist Daisy Bates, desegregated a Little Rock, Arkansas, school under the protection of military troops ordered in by the federal government. April 15: Evelyn Ashford was born (athlete, track and field; four Olympic gold medals, Track and Field Womens Hall of Fame). Althea Gibson became the first African-American tennis player to win at Wimbledon and the first African-American to win the U.S. Open. The Associated Press named Althea Gibson their Woman Athlete of the Year. 1958 August 16: Angela Bassett born (actress). 1959 March 11: Raisin in the Sun by Lorraine Hansberry became the first Broadway play written by an African-American woman - Sidney Poitier and Claudia McNeil starred. January 12: Motown Records founded in Detroit after Berry Gordy deferred working for Billy Davis and Gordys sisters Gwen and Anna at Anna Records; female stars from Motown included Diane Ross and the Supremes, Gladys Knight, Queen Latifah. December 21: Florence Griffith-Joyner born (athlete, track and field; first African-American to win four medals in one Olympics; sister-in-law of Jackie Joyner-Kersee).

Unit 2 Discussion Board Essay Example | Topics and Well Written Essays - 500 words - 1

Unit 2 Discussion Board - Essay Example The dynamic pricing strategy of Air Deccan is to use price as a function of demand and supply, wherein the earlier the booking is done the lesser is the price (About Us). To enable this pricing model made use of Information Technology to the full extent by setting up an Internet-based Centralized reservation system that centralized customers reservations through distribution channels through the Internet, call centers or travel agents. This enabled fares to be controlled by a group of computers using linear programming for revenue management. From the time a flight is opened for booking pricing is tracked and changed based on demand. The system uses a fare buckets for a given flight and fares change by the date, day of week and time of day (Sampler, 2006). The price of an air ticket booked early on Air Deccan compares favorably with an upper class rail ticket and is a boon to the more than 300 million middle class segment of society in India, which has happily accepted this means to affordable air travel. This advantage that Air Deccan offered with its dynamic pricing policy has caused a dramatic growth in the use of Air Deccan, whereby within three years since its starting, it has flown more than 5.8 million passengers and garnered a market share of 21.2 percent to become the second largest carrier in the country, pushing the national carrier Indian to third position (Air Deccan overtakes Indian in market share). Air Deccan faces two disadvantages as a result of its dynamic pricing strategy. It is facing threats to its market share from the full-service carriers in the country as well as new low-cost carriers. The full-service are lowering their airfares in the face of threat from Air Deccan and the other low-cost airlines, while the new entrant low-cost airlines are expected to use price as an entry strategy. There is no more flexibility available in pricing strategy of

The Forties World War II Essay Example | Topics and Well Written Essays - 500 words

The Forties World War II - Essay Example Churning process was going on in America that altered the political equations. The economic and social measures introduced by President Franklin D. Roosevelt brought about structural changes in the economy and the political scenario of America, with massive buildup of infrastructure and fillip to the art and cultural fronts. On the other hand, deep psychological fissures took concrete shape and administrative measures were taken to keep a watch on the ethnic groups belonging to the enemy country. Even though majority of them were citizens of America, the war situation rendered them suspect as a community. This created another area of dissention within the American society. Whether legally justified or not, American administration had no other option but to keep a close watch with some harsh measures, on the section of the population that was considered sympathetic to the enemy. The entire nation was in turmoil. Labor groups and student unions were taking up the path of communist ideology. Marxist study groups were formed at many universities for teaching that ideology to professors and students. American administration began to develop the infrastructure on a massive scale and cultural renaissance was afforded priority to keep the people engaged in arts and culture and the Federal Government took respon sibility to develop these areas. Unionization was recognized and regulated by law and this provided fillip to the worker’s movement. Most importantly, the Social Security Act was passed that ensured the welfare of the senior citizens on retirement. The Wealth Tax Act taxed the rich, brought new high revenues to the Government and a sense of relief amongst the poor that the Government is paying attention to their welfare. Japan was the enemy country and the people of Japanese origin were ordered to be interned by Executive Order No.9066 by the President Franklin D, Roosevelt issued

Shackled Women - Short Essay Essay Example for Free

Shackled Women Short Essay Essay In western cultures, women consider themselves equal to men while in some other parts of the world such as Africa and Asia, women are subjected to violence, sexual abuses, and exploitation by men that considered them as their legal or sexual property. Because tradition and religion play a crucial role in the life of the people of these regions, women are forced to live according to their culture in order for them to fit in the society. From murdered husbands in India, inhuman Islamic laws in Pakistan, to genital mutilation practice in Africa, these unjustifiable acts are virtually impossible to explain because they all go against the moral principles and values of a civilized society. When a parent deliberately killed his daughter without having remorse because of financial reasons, the first thing that comes into ordinary people’s mind is sorrow and grief. Because dowry is paid by the bride’s family in India, cruel and selfish husbands killed their second daughter in order to avoid paying a second expensive dowry. Dowry in India can account for more than 50% of a household income. (Journeyman Pictures LTD, January 2001). For that reason, fathers murdered their female child. Even if a second female child makes it trough childhood, she may still have a marriage on the rocks if her dowry is not enough to satisfy her in-laws. It is very shocking and disturbing to know that these fathers are still doing it without impunity. The most outrageous of all is that the government of India is aware of these killings and does not take drastic measures to stop it. Because it is culturally right in India to do so, women can not oppose it to the risk of being physic ally abuse by their husbands.

Business Analysis of IBM Essay -- Business Marketing IBM Companies Ess

Business Analysis of IBM 1. History of IBM: IBM is a multinational corporation that started its activities in 1911. But its origins can be traced back to 1890, during the height of the Industrial Revolution. It was first known as the Computing-Recording Company, and then in 1924, it took the name of International Business Machines. Nowadays, this multinational company is known as the  ¡Ã‚ §Big Blue ¡Ã‚ ¨ 2. Mission statement IBM main activity is to find solutions to its wide range of clients using advanced information technology. Its clients are individual users, specialized businesses, and institutions such as government, science, defense, and spatial and educational organizations. To meet and respond to its customers needs, IBM creates, develops and manufactures many of the worlds most advanced technologies, ranging from computer systems and software to networking systems, storage devices and microelectronics. Indeed, IBM has various product lines and services a few of which are: the Personal Computer that was first created in 1981, AS/400 business system, RS/6000 family of workstations and server systems, S/390 enterprise server, groundbreaking ThinkPad notebook computer; the award-winning IBM Netfinity and finally, PC Servers. It is an important supplier of hard disks, random access memories, and liquid crystal monitors. IBM has created the image  ¡Ã‚ §Solutions for a Little World ¡Ã‚ ¨. Its products and components in other firm products are so widespread that people around the world associate the name IBM with computing functions. 3. Organization IBM is a global information system and computing company. It is organized in 5 worldwide regions, and the following business units: 1.  Ã‚  Ã‚  Ã‚  Ã‚  Application Business Systems 2.  Ã‚  Ã‚  Ã‚  Ã‚  Application Solutions 3.  Ã‚  Ã‚  Ã‚  Ã‚  Enterprise Systems 4.  Ã‚  Ã‚  Ã‚  Ã‚  Networking Systems 5.  Ã‚  Ã‚  Ã‚  Ã‚  Pennant Systems Company 6.  Ã‚  Ã‚  Ã‚  Ã‚  Personal Systems 7.  Ã‚  Ã‚  Ã‚  Ã‚  Programming Systems 8.  Ã‚  Ã‚  Ã‚  Ã‚  Storage Products 9.  Ã‚  Ã‚  Ã‚  Ã‚  Technology Products 4. Past and current performance: For many years, IBM succeeded in holding a very good market position. In fact, the company achieved a very high market share and huge profits. However, this situation did not last forever. In 1990, IBM experienced its first quarterly loss of $2billion due to some unexpected accounting charges. However, revenues increased from $62.7 billion in the previous year to $96 billion. In 1991, the c... ...nies in the world were ranked: 1.IBM 2.Fujitsu 3.Hewlett-Packard 4.NEC, 5.Compaq. VI. IBM in Morocco: In 1939, IBM France launched in Morocco the first agency in Africa. Morocco was chosen because it represents an open door to Africa. IBM MAROC employs 85 employees and has almost 500 clients (ministries, banks, insurance companies, Al Akhawayn University, etc..). The main activities of IBM MAROC are to meet all customers' needs, to provide high quality tools, and to create a structure that will guarantee high quality maintenance services. IBM has two important strategies, which are: ïÆ'   direct marketing: it means selling directly to the consumer through the mail, by telephone, or door-to-door. By having direct contact with the customer, the company knows what are the needs, the preferences, and then can effectively choose the kind of products it will sell in the Moroccan market. ïÆ'   Commercial partnership: IBM has 22 commercial partners that sell its products in many different regions in Morocco. Thus, IBM MAROC is not obliged to create agencies in many cities, rather, its products are sold with other firms' articles, which increases the competition.