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Molecules and Energy Sysytems.

Extracts from this document...

Introduction

Nick Bayford AVCE SPORTS SCIENCE Molecules and Energy Sysytems The human body is very complex and for it to work properly many different nutrients are needed. Some of the nutrients are very basic and are only needed to give the body energy, but there are also nutrients that are needed so that reactions can take place in our bodies allowing them to function properly. Carbo-hydrates The main job of carbo-hydrates is to provide energy for cellular work. CHO also helps to process other nutrients. The most common form of CHO is glucose and an example of a glucose molecule is a monosaccharide ( a simple molecule which is small and travels easily through the blood system.) Monosaccharides can evolved by joinin together this process is known as polymerisation they form a disaccharide. When two monosaccharides join together (polymerisation) they form a disaccharide, a larger molecule which unlike a monosaccharide cannot be transported as easily and cannot be broken down as readily. This provides a longer supply of energy compared to a monosaccharide as it takes longer to break down. When these two monosaccharides join together they lose two hydrogen atoms and one oxygen atom in the reaction, atoms become water (H2O), when a molecule loses water in its reaction it is called a condensation reaction and synthesises a more complex molecule e.g. maltose. Polysaccharides are most commonly found in the human body in the form of glycogen - the storage form of carbohydrate found in the muscles and the liver, a polysaccharide is three to thousands of monosaccharide molecules formed in condensation reactions. "The large polysaccharide polymer formed is the glycogen-synthesising process of glucogenesis. Irregularly shaped, glycogen ranges from a few hundred to 30,000 glucose molecules linked together." (Exercise Physiology fifth edition, McArdle, Katch and Katch.2001 Maryland, USA.Lippincott Williams & Wilkins). The whole process of monosaccharides joining together, ultimately to become polysaccharides is polymerisation, this process describes the reactions that take place (condensation reaction) ...read more.

Middle

The energy from sunlight degrades to heat energy when light strikes and is absorbed. Food is an example of a basic store of potential energy. As the food decomposes however, the stores of potential energy decrease to the unusable form of kinetic or heat energy. There are six main types of energy used and produced in various metabolic pathways: * chemical - energy trapped inside a cell usually within the mitochondria * heat - a reaction that produces heat is usually the result of a series of other reactions, i.e. potential ( kinetic ( heat * potential - the storage form of energy in cells that is ready to be used e.g. triglycerides in adipocytes * kinetic- movement produced through the transfer of one energy form to another e.g. muscles contracting and relaxing * light - usually the end to a chain of reactions that produces light, that is usually derived from chemical and/or kinetic energy * mechanical - the energy used in processes such as running, a by-product of chemical/potential energy. The movement of the muscle provides the runner's mechanical energy. It is, in this way, similar to kinetic energy e.g. chemical energy ( kinetic/mechanical energy in the process of glycolysis, the Krebs Cycle and the electron transport chain. Metabolism In very simple terms, your metabolism is the rate at which your individual body burns up energy. Metabolism varies from person to person. You may have a faster metabolism than normal, for a person of your size, or a slower one. Catabolism: Catabolism is the general name given to those steps in metabolism where complex organic compounds are broken down into simpler compounds, for example the taking glucose and breaking it down into carbon dioxide and water. Anabolism: Anabolism is the general name for those steps in metabolism in which simple compounds are used to make more complex compounds, for example taking amino acids and combining them together to make proteins. ...read more.

Conclusion

As the charge builds up, it provides an electrical potential that releases its energy by causing a flow of hydrogen ions across the inner membrane into the inner chamber. The energy causes an enzyme to be attached to ADP which catalyses the addition of a third phosphorus to form ATP. In the human body the energy comes from food which is converted to pyruvate and then to acetyl coenzyme A (acetyl CoA). Acetyl CoA then enters the Krebs cycle which releases energy that results in the conversion of ADP back into ATP. The more protons there are in an area, the more they repel each other. When the repulsion reaches a certain level, the hydrogen's ions are forced out of a revolving-door-like structure mounted on the inner mitochondria membrane called ATP synthase complexes. This enzyme functions to reattach the phosphates to the ADP molecules, again forming ATP. The ATP synthase revolving door resembles a molecular water wheel that harnesses the flow of hydrogen ions in order to build ATP molecules. Each revolution of the wheel requires the energy of about nine hydrogen ions returning into the mitochondrial inner chamber. Located on the ATP synthase are three active sites, each of which converts ADP to ATP with every turn of the wheel. Under maximum conditions, the ATP synthase wheel turns at a rate of up to 200 revolutions per second, producing 600 ATPs during that second. ATP is used in conjunction with enzymes to cause certain molecules to bond together. The correct molecule first arrives in the active site of the enzyme along with an ATP molecule. The enzyme then catalyses the transfer of one of the ATP phosphates to the molecule, transferring to that molecule the energy stored in the ATP molecule. Next a second molecule arrives nearby at a second active site on the enzyme. The phosphate is then transferred to it, providing the energy needed to bond the two molecules now attached to the enzyme. Once they are bonded, the new molecule is released. ...read more.

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