Kahoot

• How does an enzyme affect a reaction?

  It reduces the activation energy
• Purpose of enzyme

  Speed up chemical reactions in a cell
• Least likely to denature an enzyme

  • Low temperature
• Regulators of enzymatic reactions

  • Inhibitors
  • Activators
• Enzymes are very specific, generally catalyzing only one chemical reaction
• Enzymes are not lipids that act as biological catalysts
• Conditions for enzymes to work best

  Temperature, pH value
• Lock and Key Model

  Developed by Emil Fisher to describe enzyme-substrate specificity
• The Lock and Key Model is not an absolute description of enzyme-substrate specificity because enzymes are flexible
• Lyases


  Enzymes that catalyze the addition of groups to double bonds or formation of double bonds by removal of groups

  
• Holoenzyme


  Enzyme + cofactor
• To increase rate of catalytic activity when competitive inhibitors are present


  Increase concentration of substrate
• Competitive and non-competitive inhibition cause Km to increase
• Catalysts decrease the free energy of the transition state in order to reduce the activation energy of the reaction
• How an enzyme increases the rate of reaction

  By stabilizing the transition state
• Competitive inhibition


  Type of enzyme inhibition

  
• Enzymes are not permanently changed in the process
• Catalase


  Breaks down hydrogen peroxide, a waste product of cell metabolism, into water and oxygen
• Isomerase


  Enzymes that catalyze the transfer of groups within molecules to yield isometric forms
• Ligases


  Enzymes that catalyze the joining of two molecules, often with the concomitant hydrolysis of a pyrophosphate bond in ATP or a similar triphosphate
• Types of cofactors


  • Inorganic cofactors (minerals)
  • Organic carrier molecules (coenzymes)
• Cofactors


  Alter the shape of enzymes slightly to make the active sites functional or to complete the reactive site
• Structure of lipids


  All have a large hydrophobic region
• Formation of triacylglycerol


  A fatty acid is esterified to each hydroxyl group of glycerol
• Main function of triacylglycerol in animal cells

  Store energy for the long term
• Functions of dietary fat

  • Provides energy
  • Forms part of cellular membranes
  • Cell signaling
• Lipids do not exhibit increased catalytic activity
• Lipids are less soluble in water
• 20:2 (Δ4,9) fatty acid


  • CH3(CH2)9CH = CH(CH2)3CH = CH(CH2)2COOH

  
• Triacylglycerol and glycerophospholipids


  Both contain fatty acids and are saponifiable

  
• Sphingolipids


  They all contain ceramide joined to a polar group
• Property of lipids in a membrane

  They would have polar heads and nonpolar tails
• Micelles of fatty acids in water

  Hydrophilic heads face the solvent, hydrophobic tails are directed to the interior

  
• Difference between saturated and unsaturated fatty acids

  The presence of double bonds

  
• Fats with unsaturated fatty acids


  Liquid at room temperature

  
• Greater the number of carbon atoms in chain of fatty acid


  The melting point will be higher
• Why butter is solid and vegetable oil is liquid at room temperature

  Butter is saturated and vegetable is unsaturated fat
• Monounsaturated fatty acid


  Oleic acid
• Linoleic acid is an essential fatty acid

  
• Naturally occurring long chain fatty acids are not all in trans configuration