Cellular Reproduction Essay -- Biology

Cellular Reproduction Cellular Reproduction is the process by which all living things produce new organisms similar or identical to themselves. This is essential in that if a species were not able to reproduce, that species would quickly become extinct. Always, reproduction consists of a basic pattern: the conversion by a parent organism of raw materials into offspring or cells that will later develop into offspring. (Encarta, 2) In almost all animal organisms, reproduction occurs during or after the period of maximum growth. (Fichter, 16). But in Plants, which continue to grow through out their lifetime, therefore making the process more complex. Plants' reproduction is usually caused by a stimulant, mostly environmental or growth factors. The reproductive process, whether asexual or sexual always involves an exchange in hereditary material from the parent(s) so that the new organism may also be able to reproduce. Reproductive processes can be categorized in many diffrent ways although the most common is to put them into either asexual reproduction or sexual reproduction. Asexual reproduction is the process by which a single organism gives rise to two or more daughter cells. Most single celled organisms reproduce by the asexual process known as fission, which is commonly called mitosis. Fission (or Mitosis) is the division of one cell into two identical daughter cells. Interphase, the first phase of the cell cycle and also the phase before mitosis, starts as soon as the cell is born. Interphase is broken up into three phases, G1, S, and G2. During the G1 phase, the cell increases in mass except for the chromosomes, which stay the same, uncoiled. Protein synthesis is also occurring rapidly in this phase. If a cell doesn't divide further, it remains permanently in the G1 phase. Next is the S phase, in which the mass of the cell continues to increase, and DNA is duplicated, and then the chromosomes divide to form identical sister chromatids attached by a centromere. (Harold, 45). During the G2 phase of Interphase, the cell becomes double its mass at birth, the chromosomes begin to shorten and coil, and the centrioles appear, the cell is now ready to enter into mitosis. In the first and longest phase of mitosis, prophase, the chromosomes become visible and the centrioles split in half and then move to opposite sides of th... ...on’t seperate correctly. This is called nondisjunction. There are three types of nondisjunction, Trisomy- when a gamete with an extra chromosome is fertiized with a normal gamete. Monosomy- when a gamete with one chromosome is missing and is then fertilized by normal gamete. And Trioloidy- where both zygotes have an extra chromosome. Reproduction is as essential to a species as food, water, or shelter. If a species cannot reproduce anymore, that species will eventually become extinct. There are many means of reproduction but primarily only two: asexual and sexual. In asexual reproduction, One organism gives a part or its whole self, in order to give rise to two or more new organisms. During sexual reproduction, two parents each form sex cells, which unite, and eventually form a new individual. Works cited Biggs, Alton & others. Biology: The Dynamics of Life. Glencoe McGraw-Hill.: New York, NY, 2000 Encarta Encyclopedia. CD-ROM. 1998 Fichter, Sheila. Reproduction. Universal Press: Columbus, OH, 1994 Harold, Christopher. Cells: A Guided Tour. Simon and Schuster: New York, NY, 1987 O’Neil, Franklin. Cells. McMeel Publishing, Inc.: Atlanta, GA, 1990

Appearance of Pre-Hispanic Filipinos Essay

The natives of the Philippine islands already wore different types of clothing and ornaments before the arrival of Spanish colonizers. The men usually wore short-sleeved, collarless jackets that reached just below the waste. The jackets were also symbols of their status in the community. The chief usually wore red, for example. The bahag was worn for the lower part. It is a strip of cloth wrapped around the waist which passes between the things, leaving the thighs and legs exposed. A head gear or a putong is a piece of cloth wrapped around the head. This is also important like the color of the jacket. A red putong meant that the wearer has already gone to war and killed an enemy. An embroidered putong meant that the wearer has killed at least seven enemies. Adornments such as necklaces, armlets or kalombiga, anklets, earrings and rings were also worn. These were usually made of gold and other precious stones. Women also wore sleeved jackets called baro and skirts called saya or patadyong. Women fancied wearing ornaments as well such as gem-studded bracelets, necklaces, earrings, and rings. Tattoos Tattoos played an important part in the appearance of pre-Hispanic Filipinos both for the men and women. Tattoos were considered to be the equivalent of medals, one had to work for and earn it. The more tattoos a person had, the more impressive was his or her war record. The Visayas was known to be the Islas del Pintados or Islands of the Painted People because it was the there that the early Spanish colonizers observed very tattooed people and Spanish writers referred to them as the pintados, meaning â€Å"painted†.

The Responsibility of the BBC Free Essay Example, 4500 words

No matter what form it takes, government regulation, co-regulation or self-regulation, the central issue will remain the quality of the programmes which are created by various broadcast stations. There can be two viewpoints taken on the subject, the first suggests that high-quality programs like the ones which were on the BBC during the golden decade of the 60s will be instantly popular and be watched with high a high number of viewers tuning. On the other hand, the other side of the argument suggests that the most popular programs are high quality, to begin with, and the masses should be given what they want not what the government thinks they should view (Dawtrey, 2004). The numbers agree with the second viewpoint, viewers will always gravitate towards what entertains them and if the news and documentary shows produced by the BBC are not good enough to keep them on the same channel, the taste of the viewers or the quality of the program should not be blamed. The BBC can go on pro ducing program after program which leaves the television critics in awe, but until the public actually approves of the programs shown by the BBC, all they would be doing is crowding the broadcast spectrum since the masses are watching something else. We will write a custom essay sample on The Responsibility of the BBC or any topic specifically for you Only $17.96 $11.86/page Once that mindset was changed a key time slot was available to the ITV to show whatever it thought would be most entertaining and it launched the famous show, Who Wants To Be A Millionaire? (Economist, 1999). Even though critics have said that the show is intellectually challenged and is not really of the caliber of other British quiz shows like Mastermind and the like, the popularity of the show can not be denied and the figures speak for themselves.