Enzymes

• Pepsin

  A type of protease enzyme, it's best in acidic conditions (pH 2) like with hydrochloric acid in the stomach that breaks down proteins into amino acids.
• Enzymes

  A protein and BIOLOGICAL CATALYSTS that speed up reactions and are produced by living organisms to regulate chemical reactions.

  • They catalyse specific reactions to ensure precision in biological processes.

  
• Structure of Enzymes

  Enzymes are large PROTEINS composed of amino acid chains, which fold into UNIQUE SHAPES that are crucial for their function.

  
• How Enzymes Work

  Lock and Key Mechanism

  • Each enzyme has an ACTIVE SITE with a shape that fits substances known as SUBSTRATES.
  • Enzymes are SPECIFIC, so only one type of enzyme will fit one type of substrate

  
• How Enzymes Work

  The specificity of enzymes catalyse a particular reaction, ensuring precision in biological processes, but enzyme's active site changes slightly to secure the substrate.

  
• Factors Affecting Enzyme Activity

  Temperature

  • As you increase the temperature, the rate of enzyme-controlled reactions also increase up to a certain point, because the enzyme and substrates move around faster meaning there are MORE COLLISIONS per second with the rate is the fastest at the OPTIMUM TEMPERATURE.

  
• Factors Affecting Enzyme Activity

  pH

  • All enzymes have an OPTIMUM pH that they work the best in and As the pH increases or decreases from the optimum, the rate of reaction DECREASES, because enzymes DENATURE causing the active site to change shape.

  
• "Lock and key theory" of enzyme action

  enzyme joins to the substrate because the substrate fits the active site, so substrate is broken down into products and products are released.

  
• CARBOHYDRASES break down carbohydrates into simple sugars.

  
• Protease enzymes

  Produced by the stomach, pancreas, small intestine

  • PROTEASES convert proteins into amino acids.

  examples of protease enzymes:

  • pepsin produced in the stomach.
  • Trypsin produced in the small intestine

  
• LIPASES  is a digestive enzyme which breaks down lipids into glycerol and fatty acids.

  • produced by the pancreas and small intestine

  
• Factors that affect rate of enzymes reaction:

  • temperature
  • pH
  • enzyme concentration
  • substrate concentration
  • surface area
  • pressure
• Trypsin is a type of protease enzyme, which works in neutral conditions like the small intestine.

  
• denature


  when the active site of the enzyme changes, since enzymes are proteins connected by bonds, so high temperature would break those bonds.

  
• The rate of reaction increases, as the temperature increases, until the optimum temperature, because the temperature gives off energy to the particles, making it collide more.

  
• • enzymes work at certain pH's
  • If pH is too high / low, it will break the bonds holding the enzymes together; changes the active site; enzymes denature.
  • enzymes have an optimum pH (works best).

  
• Amylase

  • optimum pH is 7
  • optimum temperature is 32–37 °C
• Lock and Key model (original)

  Before, scientists thought that the substrate had to fit perfectly into the active site.

  
• Induced fit model (more realistic)

  Models how the enzyme actually changes shape slightly, to mould tightly to the substrate.

  
• In order for a living cell to function properly, it has to carry out lots of chemical reactions every second of every day.
• Most chemical reactions are quite slow, so to increase the rate of the reaction is to increase the temperature, but there's problems with that:

  • as it requires a lot of energy
  • it can damage cells
  • it can also speed up non-useful reactions

  
• How temperature affect the functioning of enzymes:

  • changing temperature changes the rate of reaction.
  • Enzymes work at an optimum temperature.
  • depending on the enzyme; high temperatures starts to break the bonds holding the enzyme together and the active site starts to change shape.
  • If the active site change shape enough, then the enzyme won't be able to bind to the substrate and there's no breakdown.

  The enzyme has been denatured.

  
• How the pH affect the functioning of enzymes:

  • The pH when it's too high or low would start to break the bonds holding the enzymes together, this means that the active site starts to change shape (substrate can still fit, but less well).
  • Active site changes so much that the substrate can't fit.

  
• pH (potential of hydrogen)


  a measure of acidity
• Starch is broken down by the enzyme amylase into maltose molecules. These are then broken down further by maltase into glucose.
• AMYLASE


  • A type of carbohydrase enzyme that breaks down carbohydrates / starch into maltose (a simple sugar).

  It's produced by the:

  • salivary glands
  • mouth
  • small intestine
• Maltase


  A type of carbohydrase enzyme that breaks down maltose (a simple sugar) into two glucose molecules. (even MORE simple sugar).

  It's produced by the:
• Maltase:

  • Optimum pH: 6.5
  • Optimum temperature: 48 - 50°C
• Monosaccharides


  The simplest carbohydrates; a single sugar molecule and can't be broken down any further.

  Examples:

  • Glucose
  • Fructose
  • Galactose
• Disaccharide


  Simpler carbohydrates that are made up of two monosaccharides, which are joined together by glyosidic bonds.

  Examples:

  • Sucrose
  • Lactose
  • Maltose
• Carbohydrase enzymes:

  • Amylase
  • Maltase
  • sucrase
  • lactase
• Sugar is monosaccharides or disaccharides while starch is polysaccharides.
• reducing sugars:

  • glucose
  • fructose
  • galactose

  non-reducing sugars:

  • sucrose
  • raffinose
• Isomerase an enzyme, which is used (INDUSTRIAL) to Change glucose syrup into fructose syrup.