IGCSE Biology - Enzymes

• inhibitor


  A substance that slows down or stops a chemical reaction
• lock and key


  Model of enzyme activity that explains how a particular enzyme will only fit with one particular type of substrate.
• active site


  The part of an enzyme or antibody where the chemical reaction occurs.
• pepsin


  An enzyme present in gastric juice that begins the hydrolysis of proteins
• pectinase


  Any enzyme that breaks down pectin, a polysaccharide substrate found in the cell wall of plants, into simple sugars and galacturonic acid.
• denatured


  An uncoiled, or unraveled protein, the protein has lost its shape due to high temperatures or strong chemicals, its weak bonds have broken and the protein cannot perform its job, since it no longer "fits" with other molecules
• product

  A substance produced in a chemical reaction.
• substrate

  A substance on which an enzyme acts during a chemical reaction.
• lipase


  An enzyme secreted in the digestive tract that catalyzes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream
• catalase


  A common enzyme found in nearly all living organisms exposed to oxygen. It catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in reproductive reactions.
• protease


  An enzyme capable of digesting proteins.
• amylase


  An enzyme that is secreted by the salivary glands and by the pancreas to break carbohydrates down into sugars
• enzyme


  A type of protein that speeds up a chemical reaction in a living thing
• catalyst


  (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected
• Fruit Juice Production

  • Fruit juice is produced by squeezing fruits
  • Adding pectinase to chopped fruit helps release more juice by breaking down pectin in plant cell walls
• Everyday products made with biotechnology

  • Biofuels
  • Bread
  • Fruit Juice Production
• In countries such as Brazil, biofuel is partly replacing petrol as the fuel for cars and other vehicles
• Concerns about less land being available for local people to grow food crops due to the use of crops for ethanol production
• Bread making


  • Yeast respires anaerobically when mixed with flour and water, producing carbon dioxide which makes the bread rise
• Biofuels


  • Yeast is a single-celled fungus that uses sugar as its food source
  • Ethanol and carbon dioxide are produced when yeast respires
  • Ethanol produced by fermentation of glucose can be used as biofuel
• Producing ethanol from plant material

  1. Plant material is chopped up into small pieces and mixed with yeast for anaerobic respiration

  2. Ethanol is separated from the remaining solids and any water, leaving a concentrated solution
• Using pectinase on chopped up fruit


  More juice is released
• Many stains on clothes are organic molecules such as oil from skin, protein from blood, fat, and protein from food
• Making milk lactose-free

  Adding the enzyme lactase to milk and allowing it to stand to break down lactose
• Penicillin was the first antibiotic, discovered in 1928 by Alexander Fleming
• In certain areas, many people lose the ability to produce lactase as they age, leading to lactose intolerance
• Lactose is the sugar found in milk
• Biological washing powders contain enzymes similar to digestive enzymes in the alimentary canal to break down large food molecules
• Breaking down pectin

  Cell walls break more easily and more juice can be squeezed out of the fruit
• Penicillin is produced on a large scale using an industrial fermenter
• Symptoms of lactose intolerance include nausea, flatulence, and diarrhea
• Adding pectinase to fruits


  Produces clearer juice as larger polysaccharides like pectin can make the juice seem cloudy - once broken down, the juice becomes clearer
• Detergents containing only soap can remove some stains when mixed with hot water, but it requires a lot of time, effort, and high temperatures to remove stains entirely
• Human babies are born with the ability to produce lactase, the enzyme that breaks down lactose
• Advantages of using biological washing powders

  • Quickly break down large, insoluble molecules into smaller, soluble ones
  • Effective at lower temperatures, saving energy and money
  • Suitable for delicate fabrics not suitable for high-temperature washing
• Pectinase


  An enzyme that breaks down pectin found inside plant cell walls
• Lactose-free milk is produced by adding the enzyme lactase to dairy milk to break down sugars
• Fermenters are containers used to grow microorganisms like bacteria and fungi in large amounts for various biotechnological processes
• Penicillin produced by the fungus Penicillium inhibits bacterial growth
• Oxygenation


  Required for aerobic respiration