Enzymes and The Digestive System

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Digestion;Chemical digestion, Physical digestion – teeth, churned by stomach muscles.Chemical Digestion; Is carried out by enzymes. All digestive enzymes function by hydrolysis. Hydrolysis is the splitting up of molecules by adding water to the chemical bonds that hold them together. The general term for such enzymes is hydrolases.Usually one enzymes splits a large molecule into sections and these sections are then hydrolysed into smaller molecules by one or more additional enzymes.Three different types of enzymes: Carbohydrases break down carbohydrates.Lipases break down lipids (fats and oils). Proteases break down proteins, into amino acids. Once the large food molecules have been hydrolysed into monosaccharides, fatty acids and amino acids, they are absorbed by various means.Some molecules are incorporated into body tissues and/or used in process within the body, in a process called assimilation. Proteins, Enzymes are proteins; Structure of an amino acid:Amino acids are basic monomer units which combine to make a polymer called a polypeptide.Polypeptides combine to form proteins. Every amino acid has a central carbon atom to which four different chemical groups are attached;Amino Group (-NH2), Carboxyl Group (-COOH), Hydrogen atom (-H) R group, each amino acid has a different R group.Amino acids can combine to form a dipeptide in a condensation reaction.The two amino acids become linked by a peptide bond between the carbon atom of one amino acid and the nitrogen atom of the other. The peptide bond can be broken by hydrolysis.Primary Structure:As polypeptides have many of the 20 naturally occurring amino acids joined in any sequence, it follows that there is almost a limitless number of possible combinations, and therefore types of primary protein structure. It is the primary structure of a protein that determines its ultimate shape and its function.A change in an amino acid in this primary sequence can lead to a change in the shape of the protein and may stop it from carrying out its function. Protein’s shape is specific to its function. A protein is made up of a number of polypeptide chains. Secondary Structure:The –NH group and the –C=O group form weak hydrogen bonds.This causes the polypeptide chain to be twisted into a 3-D shape, such as an α-helix or a β-sheet. Tertiary Structure: The α-helices of the secondary protein structure can be twisted and folded to give an even more complex and often unique 3-D structure of each protein. This structure is maintained by a number of different bonds, including:Disulfide bonds – fairly strong, not easily broken down Ionic bonds – formed between any carboxyl and amino groups that are not involved in forming peptide bonds. Weaker than disulfide and easily broken by pH changes. Hydrogen bonds – numerous but easily broken. It is the 3-D shape of a protein that is important when it comes to how it functions.It makes each protein distinctive and allows it to recognise and be recognised and it can also interact with them in a specific way.Quaternary Structure: Large molecules



Reall good resource- so full of information but impossibly clear and too the point. I have one suggestion however, try seperatng the notes in to paragraphs so that its not as taxing on the eyes.

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