How do proteins in a persons food end up as a protein in that person?

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How do proteins in a persons food end up as a protein in that person?

Emma Cole

Proteins are made up of amino acid subunits.  There are about 20 different amino acids which behave in very different ways because the have different side groups.  Hence, proteins are very varied.  Each amino acid has an amino group and carboxylic acid group.

When 2 amino acids are joined together the reaction is a condensation reaction.  The amino group from one and the acid group from another form a bond producing 1 molecule of water. The bond formed is a peptide bond.  When proteins are broken down, it is a hydrolysis reaction and is the breaking of a peptide bond using a molecule of water.  

Due to the bonding and the shape and chemical nature of different amino acids, the shape of a whole chain of amino acids (a polypeptide or protein) is specific.  The primary structure of a protein is the arrangement of the long chain of amino acids in its molecule.  The secondary structure of a protein develops when parts of the polypeptide chain take up a particular shape, immediately after formation at the ribosome.  Parts of the chain become folded or twisted in various ways.  The most common shapes are formed either by coiling to produce an α-helix or folding into β-pleated sheet.  These are permanent held together by hydrogen bonds.  The tertiary structure is the precise, compact structure, unique to that protein, which arises when the molecule is further folded and held in a particular complex shape.  This shape is made permanent by 4 different bonds, between adjacent parts of the chain.

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When food is chewed and swallowed it travels down the oesophogus   by a muscular action called peristalsis and through the cardiac sphincter into the stomach.  In the stomach any bacteria in the food are killed by hydrochloric acid and protein digestion starts here.  Proteins are hydrolysed by breaking the peptide bonds between amino acids.  The enzymes that carry this out are proteases.  There are 2 types of proteases; exoprotidases and endoproteases.  Exoprotidases start at the end of the polypeptide chain breaking bonds at the end producing a mix of amino acids and di peptides.  Endoprotidases breaks bonds in the ...

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