Explain how nutrients are obtained from our diet and the contribution of each nutrient to the
- This is a preview of the essay.
To view the full text you must login!
1. Digestion, Nutrition & Bonds
Foodstuffs mainly consist of biopolymers (complex carbohydrates, proteins and lipids); large molecules made of monomers (sugars, amino acids and fatty acids/glycerol) linked together by chemical bonds. Bonds are of vital importance in living systems, as they are broken in digestion, to provide energy they are exergonic reactions - and constructed in repair and growth endergonic reactions - where the energy previously generated is harnessed.
Carbohydrates Monosaccharides 4 kcals g-1
Proteins Amino Acids (AAs) 4 kcals g-1
Lipids Fatty Acids (FAs) and Glycerol 9 kcals g-1
Whilst several bond classification systems exist the most important in physiology is the covalent bond; where two atoms 'share' outer shell electrons, making both more stable. This forms the basis of peptide; proteins, ester; fats and saccharide: carbohydrate, biopolymer backbones. The ionic bond; electrons are transferred between atoms comes a close second, they are key to the oxidation/reduction (redox) reactions, figure 1, of cellular energy generating systems whose activity is harnessed and then stored within adenosine triphosphate (ATP), (Houston, 2001).
They are also vital to the formation of ions within body fluids, e.g. Na+, Ca2+, Mg2+, Cl-, H+; all play a direct or indirect role in the energy generating pathways and in other vital areas, e.g...