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You need to know all the Standard Grade knowledge about enzymes. Construct a mind map of all the key words, and enzymes, and the reaction they speed up. P.7+8 of textbook will help with some information


Intracellular enzyme – controls processes inside cells Extracellular enzyme – controls processes outside cells


Factors Affecting Enzyme Activity 1.Temperature (See Standard Grade notes, or p.7/8 textbook) 2.pH (See Standard Grade notes, or p.8 textbook) 3.Concentration of Enzyme 4.Supply of substrate 5.Inhibitors


3. Effect of Enzyme Concentration •As enzyme concentration increases, rate of reaction increases •Rate is dependent on availability of substrate •Make sketch of Fig. 2.5 p.9


4. Effect of Substrate Concentration •Increase in substrate concentration = increase in enzyme activity •Rate continues until all active sites are occupied •Sketch Fig. 2.8 p.10


5. Inhibitors Inhibitor – substance which slows down/stops rate of reaction 2 types: 1.Competitive 2.Non-competitive


1.Competitive Inhibitors • Molecules compete with substrate for enzyme’s active site • Due to inhibitor having similar molecular structure to substarte • Active site becomes blocked and cannot be occupied by substrate => reaction rate decreases • Fig. 2.10 p.10 • Sketch Fig. 2.11 p.11 and make own notes using p.10/11


2. Non-competitive Inhibitors Inhibitor attaches to region of enzyme other than active site The attachment causes shape of active site to be altered => Substrate cannot bind with enzyme Examples – cyanide, mercury, copper, lead Fig. 2.12 p.12 Sketch fig. 2.13 p.12, and make brief notes using p.11/12


Activation of Enzymes Carried out by co-factors and co-enzymes Enable substrate to fit into active site (Fig. 2.15 np.14) Many co-factors are mineral ions (zinc, copper, iron) Co-enzymes are made with vitamins as part of their structure


•Other enzymes can also activate enzymes •Number of digestive enzymes are inactive •They are converted to active form when released into gut cavity by enzyme activators •Fig. 2.16 p.14


Inborn Errors of Metabolism Metabolism – chemical processes of the body •Metabolic pathway made up of several stages, each of which are controlled by enzymes (Fig. 2.17 p.15) •Each enzyme made from protein, coded for by part of a gene •Fault occurs => enzyme not made •Absence of enzyme – essential step cannot proceed, metabolite builds up, and can lead to problems (Table 2.2 p.15)


Ch 2 Role of Enzymes