Molecules and Energy Sysytems.

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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) when a monomer – that being a nutrient in its most simplest form e.g. monosaccharide in CHO, amino acid in protein and a fatty acid molecule in lipids, essentially a ‘building block’ forming a larger more complex dimer (two monomers) or a polymer (three or more monomers).

Fats (lipids) are another basic nutrient found in the body that performs many functions and plays several roles within. The two main functions of  lipids in the body are insulation and protection. Fat cells (adipocytes) deposit themselves in fat storage (adipose) tissue around certain parts of the body, these areas differ for men and women. Male adipose tissue is generally concentrated around the abdomen area whereas a female has larger deposits around the hips, and thighs. These deposits in females add protection to the reproductive organs in particular, cushioning and dispersing any shock away from the area. Lipids, to a slightly lesser extent are used to store vitamins in the body, “ fat-soluble vitamins dissolve and remain in the body’s fatty tissues, obviating the need to ingest them later” (Exercise Physiology fifth edition, McArdle, Katch and Katch.2001 Maryland, USA.Lippincott Williams & Wilkins).

Vitamins can be classified as fat soluble (A, D, E and K) or water soluble (C and the B-complex vitamins). The liver stores vitamins A and D, whereas vitamin E is distributed throughout the body’s fatty tissues. Vitamin K is stored only in small amounts, mainly in the liver. Toxic reactions may occur with excessive intake of fat soluble vitamins at a lower multiple of the recommended daily amount (RDA). e.g. excess vitamin A (retinol not in carotene form) and D produces serious toxic effects. Women who consume vitamin A in the early stages of pregnancy have a significant chance of increasing the risk of birth defects. In children, vitamin A accumulation causes irritability, weight loss and bone swelling. In adults, symptoms can be nausea, hair loss and calcium deficiency in the bones.

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Water soluble vitamins effectively act as coenzymes. These vitamins participate in chemical reactions after the initial reaction has finished, precipitating additional reactions. They consist largely of hydrogen, carbon and oxygen atoms, which are not stored in the body, but disperse in water and pass through in the form of urine. They have a particular importance in energy metabolism, providing links and regulating reactive factors. e.g. vitamin C’s main function is to provide connective tissue stability and to aid wound healing.

Structurally, proteins resemble carbohydrates and lipids because they contain carbon, oxygen and hydrogen atoms. In the same way that ...

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