Animal Research essays

Animal Research essays Proprietary gene targeting and nuclear transfer technology, or cloning, combined with xenotransplantation technology have proven to be one of the greatest and most practical and beneficial discovery produced by animal testing in medical laboratories. All throughout history some of the most influential discoveries in the field of psychology have been derived from experiments done on animals. There are some disadvantages to scientific research performed on animals but the advantages far more outweigh the harmful ones. There is a vast shortage of human organs available for transplantation. Waiting lists for organs can take years to budge. In America alone, there are 80,000 people waiting for organs to become available, and 15 of those waiting die every day, as stated by Robert Hager, NBC News correspondent. 5,475 Americans die every year waiting for donors to yield matching organs. Xenotransplants from another species to humans is a worthy alternative for someone who is on life support and lacks a compatible human donor organ. Xenotransplantation is a very promising and near at hand future solution to this problem. Making an alternative species donor through genetic engineering is most closely achievable by a leading biopharmaceutical company, PPL Therapeutics (PPL). PPL Therapeutics has successfully cloned a set of five piglets lacking a gene that once made full organ transplants between people and pigs not possible. What we have done is knocked out a gene which codes for an enzyme, illustrates David Ayares, Vice President of PPL Therapeutics. PPL has eliminated a gene that is responsible for making an enzyme that adds sugar to a pigs cells. When an organ that has this sugar added to its cells is transplanted into a human, it triggers a response by the patients immune system, which then causes a reaction called hyperacute rejection of the organ or a cel ...

Examples of Physical Changes

Examples of Physical Changes Physical changes involve states of matter and energy. No new substance is created during a physical change, although the matter takes a different form. The size, shape, and color of matter may change. Physical changes occur when substances are mixed but dont chemically react. How to Identify a Physical Change One way to identify a physical change is that such a change may be reversible, especially a phase change. For example, if you freeze water into an ice cube, you can melt it into the water again. Ask yourself: Is the change reversible? Not all physical changes are easy to reverse.Was there a color change (with exceptions), bubble formation, or formation of a precipitate? These are all signs of a chemical change, not a physical change.Is the chemical identity of the end product the same as it was before the change? If the answer is yes, its a physical change. If the answer is no, its a chemical change. Examples of Physical Changes Crushing a canMelting an ice cubeBoiling waterMixing sand and waterBreaking a glassDissolving sugar and waterShredding paperChopping  woodMixing red and green marblesSublimation of  dry iceCrumpling a paper bagMelting solid sulfur into liquid sulfur. This is an interesting example since the state change does cause a color change, even though the chemical composition is the same before and after the change. Several nonmetals, such as oxygen and radon, change color as they change phase.Chopping an appleMixing salt and sandFilling a candy bowl with different candiesVaporizing liquid nitrogenMixing flour, salt, and sugarMixing water and oil Indications of a Chemical Change Sometimes the easiest way to identify a physical change is to rule out the possibility of a chemical change. There may be several indications that a chemical reaction has occurred. Note: Its possible for a substance to change color or temperature during a physical change. Evolving bubbles or releasing gasAbsorbing or releasing heatChanging colorReleasing an odorInability to reverse the changePrecipitation of a solid from a liquid solutionFormation of a new chemical species. This is the best and surest indicator. A change in the chemical properties of the sample may indicate a chemical change (e.g., flammability, oxidation state).