Bio 9 (Science) Week 5 Enzymes 2024 - PDF

PowerPoint Slides for Cambridge IGCSETM Biology Student's Book CHAPTER 5 ENZYMES © 2021 Marshall Cavendish Education Pte Ltd The following content has not been through the Cambridge Assessment In...

PowerPoint Slides for Cambridge IGCSETM Biology Student's Book CHAPTER 5 ENZYMES © 2021 Marshall Cavendish Education Pte Ltd The following content has not been through the Cambridge Assessment International Education endorsement process. ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book Today’s Agenda Look at our today’s agenda! © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book https://www.youtube.com/ watch?v=qgVFkRn8f10 https://www.youtube.com/ watch?v=Xtz-Ew9OkKA © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book Look at this map! Do you have any questions? © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book 5.1 Enzymes Are Biological Catalysts In this section, you will learn the following: Describe a catalyst as a substance that can increase the rate of a chemical reaction, without being chemically changed by the reaction. Describe enzymes as biological catalysts, which are made of proteins and are involved in all metabolic reactions. Describe why enzymes and reaction rate are important in sustaining life in living organisms. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book Step 1 https://www.youtube.com/ watch?v=qgVFkRn8f10 © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book What reactions do enzymes catalyse? Only small molecules such as glucose and amino acids can pass through the cell membrane. (Figure 5.2 of Student’s Book) © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book What reactions do enzymes catalyse? 1. Reactions that build up or break down complex substances: https://www.youtube.com/watch?v=gG7uCskUOrA Cells build up or synthesise Cells break down complex complex substances from substances to simple substances. simpler ones. Example: Example: Enzymes catalyse practically all the chemical reactions that occur in an organism, but they are produced only when needed. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book How are enzymes named? The name of each enzyme shows the substance on which the enzyme acts; ends in ase. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book 5.2 How Does an Enzyme Work? In this section, you will learn the following: Describe enzyme action in terms of the complementary shape of the active site to its substrate and product formation. Explain enzyme action in terms of the active site, enzyme-substrate complex, substrate and product formation. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book How does an enzyme work? The substance on which an enzyme acts is called a substrate. Each enzyme has a groove on its surface called the active site. Only a substrate with a complementary shape can fit into the active site (just like a key fitting into a lock). When the substrate binds to the active site of the enzyme, an enzyme-substrate complex is formed. Three-dimensional model of enzyme pepsin with its active site © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book How does an enzyme work? The mode of action of an enzyme (Figure 5.6 of Student’s Book) © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book 5.3 Characteristics of Enzymes In this section, you will learn the following: Investigate and describe the effect of temperature and pH on enzyme activity. Explain enzyme-substrate specificity. Explain the effect of temperature on enzyme activity. Explain the effect of pH on enzyme activity. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book What are the characteristics of enzymes? 1. Enzymes catalyse reversible reactions. 1. Every enzyme has an optimum pH at which it is most active. Some reactions in living cells can proceed Extreme changes in the acidity or alkalinity of the solutions in a forward or backward direction. denature the enzymes. Example: At pH 4 or above 9, the 1. Enzymes are catalysts. enzyme is completely Enzymes speed up the rates of chemical denatured. The active site reactions that occur in a cell. of the enzyme loses its original shape. Effect of pH on the rate of reaction catalysed by amylase © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book What are the characteristics of enzymes? 1. Enzymes are required in minute amounts. 1. Every enzyme has an optimum temperature at which it is A small amount of enzyme can catalyse a most active. large number of chemical reactions. Increasing the temperature from low to the optimum temperature increases the rate of enzyme reaction. Increasing the temperature above the optimum temperature 1. Enzymes are specific in action. causes a rapid decrease in the rate of reaction. Only a substrate with a shape complementary to that of the active site can fit into the enzyme to form the enzyme-substrate Increasing the complex. temperature increases the kinetic motion of molecules, resulting in an increased rate of effective collision between the enzyme and substrate molecules. This increases the proportion of effective collisions. Effect of temperature on the rate of enzyme reaction © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book What causes enzymes to denature? Denaturation is the change in the three-dimensional structure of an enzyme or any other soluble protein, caused by heat or chemicals. Denaturation results in the loss or alteration of the enzyme’s active site, such that the substrate can no longer fit into the enzyme. At temperatures above 45°C, some enzymes are denatured. Enzymes lose their active sites when they are denatured. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book At very low temperatures, amylase is inactive. The activity of amylase increases as the temperature increases. Beyond a certain temperature, the activity of amylase decreases. Amylase is denatured at very high temperatures. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book In test-tube A, the protein in egg white will be digested to a soluble product. There will be no change in test-tube C as the contents in the test-tube are alkaline. Test-tube B is the control. Test-tube D shows that pepsin is inactive in neutral conditions. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book 1. “Without digestive enzymes, some food molecules are useless to the body.” Is this statement valid? Why or why not? 2. The unripe fruit of the papaya tree contains a particular type of digestive enzyme that is often used to soften meat. (a) Infer the kind of organic molecule that this enzyme acts on. (b) Suggest how the enzyme may cause the softening of meat. © 2021 Marshall Cavendish Education Pte Ltd ‹#›  PowerPoint Slides for Cambridge IGCSETM Biology Student's Book Wrap-up Let’s play a quiz on your personal learning device to test your prior knowledge from the past lessons! Launch Quiz © 2021 Marshall Cavendish Education Pte Ltd ‹#›