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Protein

Protein. 1 of the 3 macronutrients. Elemental Composition. Proteins are made up of atoms of: Carbon C Hydrogen H Oxygen O Nitrogen N and sometimes small amounts of Phosphorus (P), Sulphur (S) and Iron (Fe) Nitrogen is needed for growth.

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Protein

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  1. Protein 1 of the 3 macronutrients

  2. Elemental Composition Proteins are made up of atoms of: Carbon C Hydrogen H Oxygen O Nitrogen N and sometimes small amounts of Phosphorus (P), Sulphur (S) and Iron (Fe) Nitrogen is needed for growth. Proteins are the only nutrients that contain the element nitrogen. These elements are bonded together in small molecules called amino acids. Amino acids are bonded together into long chains called proteins

  3. Basic Structure of protein – Amino Acids • There are 20 different amino acids but each has the same basic structure. C = carbon atom H= Hydrogen atom NH2 = Amino group COOH = Carboxyl group R = Variable group e.g. in the amino acid Glycine the R = H (one Hydrogen Atom)

  4. Formation of a Peptide Bond CONH H2O

  5. Biological Value of Protein The Biological Value of a protein is a measure of the quality of the protein and is expressed as a %.

  6. Sources of protein

  7. Essential Amino Acids • There are over 20 different amino acids. • 8 are Essential Amino Acids that cannot be made by the body and must be eaten e.g. Lysine, Leucine, Isoleucine. • There are 2 extra essential amino acids for children- Arginine and Histidine • The rest are Non-Essential Amino Acids these can be made by the body e.g. Glycine, Cystine, Cysteine.

  8. Supplementary Value of Protein • When low biological value foods, that lack essential amino acids, are eaten together they can provide all the essential amino acids. • The essential amino acids missing in one food can be made up for by being present in the other food and visa versa. • This complementary value of protein means that vegans can get all the essential amino acids without eating animal food • Example; Bread is lacking Lysine but is high in Methionine. Beans are lacking Methionine but high in Lysine. By eating beans on toast both essential amino acids are included in the meal.

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