TOPIC 2.5 - ENZYMES

2.5 – A - Enzymes

IB BIO – 2.5 Enzymes are proteins that speed up specific chemical reactions (anabolic or catabolic). Each enzyme has an active site that allows it to bind to a specific substrate. 3 Understandings U1: Enzymes have an active site to which specific substrates bind. Key Terms Enzyme Active Site https://upload.wikimedia.org/wikipedia/commons/9/9f/Lock_and_key.png

IB BIO – 2.5 The structure and chemical properties of an enzyme’s active site is complementary to the substrate molecule it binds to. In order to catalyze the reaction, the substrate must collide with the enzyme’s active site. When this happens, they form the enzyme- substrate complex. 4 Understandings U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site. Key Terms Enzyme Active Site https://o.quizlet.com/ra0rUyR3-tPrn4JUZnHT8w_m.jpg

IB BIO – 2.5 After it binds to the active site, the substrate is broken down by the enzyme. The products are then released into the environment. The enzyme is unchanged and can then bind to another substrate. 5 Understandings U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site. Key Terms Enzyme Active Site https://o.quizlet.com/ra0rUyR3-tPrn4JUZnHT8w_m.jpg

https://d2gne97vdumgn3.cloudfront.net/api/file/jRZnIYYT8uZZaNQQZnww IB BIO – 2.5 The specificity of enzymes is often called the lock-and-key model, since only one specific substrate can bind to each active site. 6 Understandings U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site. Key Terms Enzyme Active Site https://d2gne97vdumgn3.cloudfront.net/api/file/jRZnIYYT8uZZaNQQZnww

https://d2gne97vdumgn3.cloudfront.net/api/file/jRZnIYYT8uZZaNQQZnww IB BIO – 2.5 Immobilized enzymes are those that are attached to a material so that it stays in place. To fix them in place, they can be: Bound to solid or porous materials Mixed in with a matrix Embedded in a soluble membrane These enzymes are not changed in reactions and so can be used many times when substrates pass over them 7 Understandings U5: Immobilized enzymes are widely used in industry. Key Terms Immobilized Enzymes https://d2gne97vdumgn3.cloudfront.net/api/file/jRZnIYYT8uZZaNQQZnww

IB BIO – 2.5 Immobilized enzyme have been used in carbon capturing. Polluted air is passed over enzymes, which traps CO2 for storage. This technology is being used to reduce emissions from factories. 8 Understandings U5: Immobilized enzymes are widely used in industry. Key Terms Immobilized Enzymes https://www.sciencenews.org/sites/default/files/main/articles/CO2_full.jpg

IB BIO – 2.5 Immobilized enzymes are also used in producing lactose-free milk. Lactase is immobilized in alginate beads and then milk is passed 9 Applications A1: Methods of production of lactose-free milk and its advantages. over. This breaks lactase into glucose and galactose monomers. Since the enzymes are bound, they do not wash away and can be used many times. Key Terms Lactase Lactose-Free Milk http://www.abpischools.org.uk/cnt/txt/177/1/milk.gif

IB BIO – 2.5 Because lactose-free milk has more sugar monomers, it tastes sweeter. Manufacturers use this to sweeten dairy products without adding extra sugars. 10 Applications A1: Methods of production of lactose-free milk and its advantages. Key Terms Lactase Lactose-Free Milk https://edc2.healthtap.com/ht-staging/user_answer/avatars/512032/large/open-uri20121120-14183-15pvkal.jpeg

REVIEW IB BIO – 2.5 Define enzyme. Outline enzyme-substrate specificity. Define immobilized enzymes Descibe the use of enzymes in production of lactose-free milk. 11 REVIEW

2.5 – B – Enzyme Rates

IB BIO – 2.5 The function of enzyme is to increase the rate of reactions. However, their ability to to do can be affected by the environment. Relevant factors include: - Temperature - pH - Substrate Concentration 13 Understandings U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes. Key Terms https://upload.wikimedia.org/wikipedia/commons/thumb/2/24/Induced_fit_diagram.svg

IB BIO – 2.5 Like other proteins, enzymes can be denatured when exposed to conditions that interfere with internal amino acid interactions. Each enzyme has optimum conditions in which it most effectively catalyzes reactions. This is usually related to the habitat of an organism or a cell’s location within the body. 14 Understandings U4: Enzymes can be denatured. Key Terms Denaturation http://www.che.caltech.edu/groups/fha/media/Fuels_figs/Fuels_fig3.jpg

IB BIO – 2.5 Enzymes catalyze reactions at an optimum temperature, which is typically related to environment. High temperatures cause the enyme to denature, which quickly decreases activity. As temperature falls below the optimimum, molecular collisons decrease. This causes the reaction rate to fall. 15 Understandings U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes. Key Terms http://biology4isc.weebly.com/uploads/9/0/8/0/9080078/6069215_orig.jpg

IB BIO – 2.5 For example, the bacteria shown below each have a different optimal temperatures for catalyzing the same reaction. 16 Understandings U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes. Key Terms http://www.che.caltech.edu/groups/fha/media/Fuels_figs/Fuels_fig3.jpg

IB BIO – 2.5 Enzyme also have an optimal pH. When conditions deviate from it and become too basic or acidic, the enzyme can denature. Optimum pH varies widely among enzymes. For example, the optimum pH of stomach protease can be as low as 1.6. 17 Understandings U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes. Key Terms pH http://schoolbag.info/chemistry/mcat_biochemistry/mcat_biochemistry.files/image041.jpg

Substrate Concentration IB BIO – 2.5 Substrate concentration refers to the amount of substrate available to the enzyme’s active site As concentration decreases, reaction rate decreases. As concentration increases, reaction rate increases. When all enzyme active sites are filled, the reaction is saturated and the reaction rate plateaus. 18 Understandings U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes. Key Terms Substrate Concentration https://upload.wikimedia.org/wikipedia/commons/thumb/0/09/KinEnzymo(en).svg

IB BIO – 2.5 Draw a graph showing the effects of the following factors on enzyme reaction rates: - Temperature - pH - Substrate Concentration On the graphs you drew, add a dotted line showing the effects of decrease/increasing each factor. Be sure to label your lines. 19 REVIEW