Biology Enzymes. Slide 1 / 64. Slide 2 / 64. Slide 3 / 64. Vocabulary Click on each word below to go to the definition

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1 Slide 1 / 64 Slide 2 / 64 iology Enzymes Vocabulary lick on each word below to go to the definition. Slide 3 / 64 activation energy active site allosteric regulation catalyst coenzyme cofactor competitive inhibitor enzyme feedback inhibition induced fit noncompetitive inhibitor optimal ph optimal temperature substrate

2 Enzymes Unit Topics Slide 4 / 64 lick on the topic to go to that section Enzymes, atalytic ycle Temperature, ph, Inhibition llosteric Regulation, Feedback Inhibition Enzymes, atalytic ycle Slide 5 / 64 Return to Table of ontents atalysts Slide 6 / 64 catalyst is a substance which speeds up chemical reactions without being changed by the reaction. When a catalyst is present, less energy is needed to start a chemical reaction. When a catalyst is present, the speed of a chemical reaction is faster. The catalyst remains unchanged at the end of the reaction.

3 Enzymes Slide 7 / 64 Enzymes are catalysts in biological systems. In early cells, enzymes were made of. In modern cells, enzymes are a type of. ommon Enzymes Slide 8 / 64 Lactase is an enzyme that helps us to digest dairy products. People with lactose intolerance have trouble digesting dairy because they lack this enzyme, but they are able to take a lactaid pill that contains the enzyme lactase. ommon Enzymes Slide 9 / 64 mylase is an enzyme found in human saliva. It begins the chemical process of digestion. Typically, you can identify an enzyme by its -ase ending.

4 Enzyme Substrate omplex Slide 10 / 64 Enzymes help chemical reactions occur by providing a space called an active site for the substrates (reactants), to bind. substrate ctive site Substrate entering active site of enzyme Enzyme/substrate complex Enzyme/products complex Products leaving active site of enzyme lick here to see a video on Enzymes Induced Fit Slide 11 / 64 Just as a key can only open a specific lock, each enzyme has its own unique shape, so each enzyme is specific to certain substrates. s the substrates enter the active site, the enzyme's shape changes just a little in order to create a better fit, called an induced fit. atalytic ycle of an Enzyme Slide 12 / 64 n enzyme is capable of being used again and again to allow more of the same reactions to occur.

5 1 Which of the following acts as a catalyst in the body? Slide 13 / 64 E arbohydrates Nucleic cids Lipids Enzymes Water 2 nother name for protein reactants is. Slide 14 / 64 products substrates active sites enzymes 3 Enzymes bind only to certain substrates. Slide 15 / 64 True False

6 4 n enzyme can only be used for one reaction and then it will not work again. Slide 16 / 64 True False ctivation Energy Slide 17 / 64 Enzymes work by decreasing the minimum amount of energy required for reaction. This is called the activation energy, Ea. Just as a ball cannot get over a hill if it does not roll up the hill with enough energy, a reaction cannot occur unless the molecules possess sufficient energy to get over the activation energy barrier. Potential Energy iagrams Slide 18 / 64 This activation energy is usually needed to break bonds in the substrate. final energy initial energy

7 atalysts Slide 19 / 64 Enzymes increase the rate of a reaction by decreasing the activation energy of the reaction. This graph shows the decomposition of a sugar both with and without a catalyst. Notice that the initial energy of reactants and the final energy of the products are unchanged by the catalyst. 5 ctivation energy is. the heat released in a reaction Slide 20 / 64 the energy given off when reactants collide generally very high for a reaction that takes place rapidly an energy barrier between reactants and products 6 What happens to a catalyst in a reaction? Slide 21 / 64 It is unchanged. It is incorporated into the products. It is incorporated into the reactants. It evaporates away.

8 7 Why does a catalyst cause a reaction to proceed faster? Slide 22 / 64 Only because there are more collisions per second. Only because collision occur with greater energy. Only because the activation energy is lowered. There are more frequent collisions and they are of greater energy. 8 If a catalyst is used in a reaction. Slide 23 / 64 the energy of activation increases different reaction products are obtained the reaction rate increases it evaporates away Temperature, ph, Inhibition Slide 24 / 64 Return to Table of ontents

9 Enzymes Have Optimal Environments Slide 25 / 64 Since enzymes are proteins and proteins are sensitive to their environments, enzymes are also sensitive to their environments. Factors ffecting Enzyme ctivity Temperature ph Effect of Temperature on Enzymes In general, increasing the temperature of a system increases the reaction rate because the substrates are able to move faster and have more collisions with the active sites of the enzymes. Slide 26 / 64 This is true only up to certain temperatures for each type of enzyme! We call this temperature the optimal temperature. The optimal temperature is different for each type of enzyme. Effect of Temperature on Enzymes Slide 27 / 64 Past the optimal temperature, the enzyme begins to denature or lose its shape, which changes the shape of the active site.

10 Optimal Temperature and Fever Slide 28 / 64 Fever is the elevation of body temperature above normal (In humans 98.6 o F). Typically, fevers develop in response to bacterial or viral infection. The optimal temperature for most bacterial enzymes is less than 98 o F, so by raising body temperature above that, the immune system attempts to denature the bacteria's enzymes and stop the infection. ommon Enzymes Slide 29 / 64 Laundry detergents contain enzymes that help break up and remove stains from your clothing. Why might you want to use a different laundry detergent when you wash clothes in hot water instead of in cold water? Effect of ph on Enzymes Slide 30 / 64 Increasingly cidic [H+] > [OH ] ph level can also cause a denaturing of the enzyme. Most biological solutions have ph values between 6-8.

11 Effect of ph on Enzymes Slide 31 / 64 The optimal ph for most enzymes is between 6-8, but again the optimal ph is different for each type of enzyme. (optimal ph = 4.2) 9 What is the optimal temperature for this enzyme? Slide 32 / What is the optimal ph of this enzyme? Slide 33 / 64

12 11 Which enzyme has a lower optimal temperature? Slide 34 / t which temperature do both enzymes have an equal rate of reaction? Slide 35 / Which description best explains the temperature effects shown in the graph? Slide 36 / 64 Each enzyme will function at room temperature. oth enzymes are inactive at the freezing point. Each enzyme has its own optimal temperature range. oth enzymes have the same optimal temperature range.

13 14 ased on this information which environment can you conclude as being more acidic? Slide 37 / 64 Stomach Liver Stomach Enzyme Liver Enzyme 15 Which enzyme would you choose to use in a basic environment? Slide 38 / The active site of an enzyme I. is the part where a substrate can fit II. can be used again and again III. is not affected by environmental factors Slide 39 / 64 E I only II only III only I and II I and III

14 ofactors Sometimes enzymes need a helper to bind at the active site to make the enzyme active. These helpers are called cofactors. Slide 40 / 64 If the cofactors are organic molecules, then they are called coenzymes. Vitamins are a type of coenzyme. coenzyme substrate Enzyme Enzyme Inhibitors Slide 41 / 64 ertain chemicals work to stop or inhibit the enzymes. These chemicals are called enzyme inhibitors. Types of Inhibitors ompetitive Inhibitors Noncompetitive Inhibitors click here for an animation about inhibition ompetitive Inhibitors Slide 42 / 64 ompetitive inhibitors are similar in shape to the substrates. ompetitive inhibitor They are able to block the substrates from binding to the active site by binding to the active site themselves.

15 ompetitive Inhibitors: How They re Stopped Slide 43 / 64 To stop competitive inhibition, the concentration of the substrates needs to be increased so that they outnumber the inhibitors. This way, the substrates are more likely to bind to the active site before an inhibitor does. Noncompetitive Inhibitors: How they work Slide 44 / 64 Noncompetitive inhibitors bind to a separate part of the enzyme and cause the enzyme to change shape. When the enzyme changes shape, the substrate is no longer able to bind to the active site because the active site also changes shape. This type of inhibition is sometimes irreversible. 17 Organic molecules that aid in the action of the enzyme are called. products coenzymes substrates helpers Slide 45 / 64

16 18 Which type of inhibitor binds at the active site? Slide 46 / 64 ompetitive Inhibitor Noncompetitive Inhibitor 19 Noncompetitive inhibitors are similar in shape to the substrates that bind at the active site of an enzyme. Slide 47 / 64 True False 20 If an enzyme has been inhibited noncompetitively,. the enzyme is able to increase its activity increasing substrate concentration will increase inhibition Slide 48 / 64 the active site will be occupied by the inhibitor molecule the active site will change shape

17 21 Noncompetitive inhibition is sometimes irreversible. Slide 49 / 64 True False llosteric Regulation, Feedback Inhibition Slide 50 / 64 Return to Table of ontents llosteric Regulation Slide 51 / 64 In most natural processes it is necessary to regulate enzyme activity. This regulation can either be to inhibit or to stimulate activity. llosteric regulation is a type of noncompetitive inhibition that is reversible.

18 llosteric ctivation and Inhibition Slide 52 / 64 Enzymes that undergo allosteric regulation are usually made of multiple subunits or polypeptide chains. ll of the subunits together form a complex that can be in an active or inactive position. Where the subunits connect, there is an allosteric site, or a site that allows an activator or inhibitor molecule to bind. llosteric Inhibitors Slide 53 / 64 llosteric ctivators Slide 54 / 64 If an inhibitor binds to the enzyme, the subunits are stabilized in an inactive form. This means the enzymes changes shape and the active sites are not open for substrates to bind to. llosteric ctivators bind to the enzyme, stabilizing the subunits in an active form. This means the enzymes change shape and the active sites are available for substrates to bind to.

19 Slide 55 / 64 Feedback Inhibition Slide 56 / 64 In certain processes the products from one enzyme act as the substrates for a second enzyme and and the second enzyme's products are a substrate for a third enzyme etc. When this happens, the products from the last enzyme in the path can allosterically inhibit the first enzyme in the path until it is necessary for more of the products to be made again and then the inhibitor leaves. This is called feedback inhibition. lick here to see a video of Feedback Inhibition Feedback Inhibition Slide 57 / 64 Initial Substrate End Product enzyme 1 + X Intermediate enzyme 2 Intermediate enzyme 3 End Product

20 22 n allosteric site on an enzyme is Slide 58 / 64 not made of protein involved in feedback inhibition the same as the active site where the products leave the enzyme 23 Which of the following is not part of allosteric regulation? other substrate molecules compete for the active site regulatory molecules bind to a site separate from the active site Slide 59 / 64 inhibitors and activators may compete with one another a naturally occuring molecule stabilizes an active conformation 24 llosteric regulation is similar to noncompetitive inhibition except that it is. Slide 60 / 64 always reversible sometimes irreversible

21 25 In allosteric regulation the sites where the inhibitors and activators are able to bind are called. Slide 61 / 64 ctive Site Substrates llosteric Site ofactors 26 In allosteric regulation both an inhibitor and an activator can bind to one substrate complex at the same time. Slide 62 / 64 True False 27 Feedback inhibition is a type of. Slide 63 / 64 competitive inhibition product allosteric regulation enzyme

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