enzymes

• Enzymes are biological catalysts that speed up reactions that breakdown macromolecules into their smaller products, by lowering the activation energy needed for a reaction to proceed.
• The active site is the region of an enzyme that has a complementary shape to its specific substrate group allowing them to bind.
• The substrate are the molecules an enzyme binds to and acts on the site.
• Products are molecules made in a chemical reaction.
• Substrate


  A molecule that binds to an enzyme in order for the substrate to react faster and form product/s.
• amylase 


  Is an enzyme that breaks down starches into maltose via a catabolic reaction, it is produced by the salivary glands and the pancreas and active in the mouth and small intestine (duodenum).
• Maltase


  Maltase converts maltose into glucose via a catabolic reaction, it is produced by the small intestine and is active in the small intestine.
• Pepsin 


  pepsin breaks down proteins into peptides, pepsin is produced in the stomach and is active in the stomach. Pepsin has an optimal pH of approx 1.5
• peptidase 


  peptidase helps convert peptides into amino acids. Peptidase is secreted by the small intestine and active in the small intestine.
• lipase


  lipase helps break down lipids to fatty acids and glycerol, it is produced by the pancreas and is active in the small intestine
• Mucous

  Mucous helps with the lubrication of food masses in order to facilitate movement within the stomach and the formation of a protective layer over the lining epithelium of the stomach cavity.
• Hydrochloric acid 


  Helps to kill pathogens (e.g bacteria) on food and provides the optimal pH environment for pepsin to function.
• Bile

  Bile emulsifies fat by breaking large fat droplets into smaller fat droplets, and increases the Surface area for lipase to react.
• Alkaline pancreatic juices (bicarbonate Ions) $HCO_3^-$


  Alkaline pancreatic juices help neutralise the stomach acid (hydrochloric acid) that inters the small intestine along with the chyme. This is to ensure that the intestinal lining is not damages and do that the optimal pH is reached for the intestinal enzymes to maximise enzyme activity. Pancreatic juices also denature pepsin.
• enzymes must remain inactive in the cells that produce them so that they dont start catalysing the breakdown of macromolecule within that cell, this would result in cellular damage
• if an enzyme is outside of its optimal pH, the chemical bonds holding an enzyme’s unique 3D shape together will break, denaturing the enzyme so it loses its active site & cannot bind to its substrate.
• if an enzyme is outside of its optimal temperature, At lower than optimal temp. there is less energy available for molecule movement so enzymes collide with their substrates less often and reaction rates slow down, at temperatures above optimal, the enzyme will denature
• denature


  When the bonds holding a protein’s 3D shape together are broken, this changes the 3D shape of the protein and it is said to be denatured. When an enzyme is denatured, its active site also changes shape so that it can not bind to its substrate & thus cannot catalyse a reaction