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1 Enzymes Place cracker in mouth!! What happens!! WHY????? Would this happen with a piece of meat? Why or why not?

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Presentation on theme: "1 Enzymes Place cracker in mouth!! What happens!! WHY????? Would this happen with a piece of meat? Why or why not?"— Presentation transcript:


2 1 Enzymes

3 Place cracker in mouth!! What happens!! WHY????? Would this happen with a piece of meat? Why or why not?

4 Enzyme Roles Anabolic - building molecules synthesis Catabolic -breaking down molecules digestion + +

5 Bond Energy BOND ENERGY :Amount of energy needed to break the bonds between molecules. Energy is needed to break bonds. The stronger the bond the more energy needed. The amount of energy is different for all bonds. Energy is released when bonds are formed like with H and O to make water.

6 Activation Energy Energy needed to get the reaction started. Photosynthesis: sunlight Fuel: match

7 Activation Energy Energy needed to get the reaction started. Some reaction takes more energy than others. Usually this is increasing the temperature but organisms cannot change the temperature so something else has to help decrease the amount of energy needed. We cannot use all our energy for reactions like photosynthesis and respiration.

8 Increase of Temperature Can organisms have a great increase in temperature? Need other ways to get increase or to decrease the amount of activation energy needed This is where catalysts come into play.

9 CATALYST A substance that decreases the activation energy needed to start a reaction. Usually temperature increase but organisms cannot have a great increase in temperature or die Increases the rate of reaction or speed of reactions. They break the bonds between the reactants to speed up the reaction.


11 Digestive enzymes are secreted by the body to digest the food eaten. There are three categories of digestive enzymes: Amylases (found in saliva, the pancreas, and intestinal juices) break down carbohydrates; Proteases (found in the stomach, pancreatic, and intestinal juices) help digest protein; Lipases (pancreatic juices, and in food fats) aid in fat digestion.

12 Amylase enzymes are found in the saliva and in the juices of the pancreas and intestinal tract and help the digestive process by breaking down carbohydrates. There are different kinds of amylase. For example, the enzyme sucrase breaks down the sugar sucrose found in cane and beet sugar. The enzyme lactase breaks down the lactose sugar in milk. The enzyme maltase breaks down the malt sugar maltose. Protease enzymes are found in the juices of the pancreas, the stomach and the intestinal tract and help with the breakdown and the digestion of proteins. Lipase enzymes are found in the juices of the stomach and pancreas and help to break down fats.

13 ENZYMES * A protein that acts as a catalyst which lowers activation energy needed to start a reaction. *They speed up reactions by weakening bonds. *Always in in -ase © 2007 Paul Billiet ODWSODWS

14 13 How do enzymes Work? weakening bonds which lowers activation energy. Enzymes work by weakening bonds which lowers activation energy. Easier to start reaction!!!

15 14Enzymes catalyze Are specific for what they will catalyze Reusable Are Reusable ase End in –ase-Sucrase-Lactase-Maltase

16 Enzymes have five important properties: 1. They are always proteins. 2. They are specific in their action. Each enzyme controls one particular reaction, or type of reaction. Thus sucrase degrades sucrose and only sucrose (table sugar). ONE SUBSTRATE!!! 3. They are not altered by the reaction. This means that an enzyme can be used repeatedly. It also means that enzymes appear neither in the reactants nor in the products of a chemical equation. 4. They are destroyed by heat. This is because enzymes are proteins, and all proteins are destroyed by heat. Destruction of protein by heat (or under any extreme conditions of pH or salt concentration) is called denaturation. 5. They are sensitive to pH. The term pH refers to the degree of acidity and alkalinity of a solution. Most intracellular enzymes work best in neutral conditions, i.e. conditions that are neither acidic nor alkaline.

17 The substrate The substrate of an enzyme are the reactants that are acted on by the enzyme. Enzymes are specific to their substrates The specificity is determined by the active site ENZYMES ARE SHAPED TO FIT ONLY THEIR SUBTRATE BECAUSE THEIR ACTIVE SITE IS SHAPED TO FIT ONLY ONE SUBSTRATE!!!! © 2007 Paul Billiet ODWSODWS


19 18 Active Site restricted region enzyme binds substrate A restricted region of an enzyme molecule which binds to the substrate. Enzyme Substrate Active Site

20 19 Enzyme-Substrate Complex This is the product of the substrate and the enzyme together. Enzyme Substrate Joins



23 The Lock and Key Hypothesis Fit between the substrate and the active site of the enzyme is exact Like a key fits into a lock very precisely The key is analogous to the enzyme and the substrate analogous to the lock. Temporary structure called the enzyme- substrate complex formed © 2007 Paul Billiet ODWSODWS

24 Enzyme Structure It fits like a lock and key with its substrate. Will not fit any other substance. How Enzymes Work: 1. Enzyme brings molecules close together. 2. By bonding they have weaken the bonds of the substrate so they reaction can occur quicker.

25 24 Induced Fit shape A change in the shape of an enzyme’s active site Induced Induced by the substrate

26 25 Induced Fit changeconfiguration enzyme’s active site A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). Inducedsubstrate. Induced by the substrate. Enzyme Active Site substrate induced fit

27 26 What Affects Enzyme Activity? Three factors: Three factors: 1.Temperature 2. pH 2. pH 3.Inhibitors

28 Denaturing Enzymes Denaturing =- factors that change the shape. Without the correct shape enzymes won’t function properly. HOW are enzymes denatured? Temperature *pH Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College

29 Temperature Optimum temperature greatest number of collisions between enzyme & substrate human enzymes 35°- 40°C (body temp = 37°C) F Raise temperature (boiling) denature protein = unfold = lose shape Lower temperature T° molecules move slower fewer collisions between enzyme & substrate

30 The effect of temperature For most enzymes the optimum temperature is about 30°C Many are a lot lower, cold water fish will die at 30°C because their enzymes denature A few bacteria have enzymes that can withstand very high temperatures up to 100°C Most enzymes however are fully denatured at 70°C © 2007 Paul Billiet ODWSODWS

31 37° Temperature temperature reaction rate What’s happening here?! human enzymes

32 The effect of temperature Temperature / °C Enzyme activity Q10 Denaturation © 2007 Paul Billiet ODWSODWS

33 How do cold-blooded creatures do it?

34 Enzymes work in different pH All enzymes can work in different conditions Intestines would have a lower pH than mouth.

35 The effect of pH Extreme pH levels will produce denaturation The structure of the enzyme is changed The active site is distorted and the substrate molecules will no longer fit in it At pH values slightly different from the enzyme’s optimum value, small changes in the charges of the enzyme and it’s substrate molecules will occur © 2007 Paul Billiet ODWSODWS

36 pH changes in pH changes protein shape most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

37 The effect of pH Optimum pH values Enzyme activity Trypsin Pepsin pH © 2007 Paul Billiet ODWSODWS

38 7 pH reaction rate stomach pepsin intestines trypsin What’s happening here?!

39 Analyze the graph at what ph does Chymotrypsin function best?


41 Inhibitors Inhibitors are chemicals that reduce the rate of enzymic reactions. The are usually specific and they work at low concentrations. They block the enzyme but they do not usually destroy it. Many drugs and poisons are inhibitors of enzymes in the nervous system. © 2007 Paul Billiet ODWSODWS

42 Enzyme Inhibitors Inhibitors - Chemicals that bind in the active site. Inhibitors decrease the enzyme reaction rate. Most poisons work by affecting enzyme activity Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College

43 42 Inhibitors Inhibitors: resembleenzyme’s normal substrate compete active site Inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Competitive inhibitor Substrate

44 Snake Venom Enzymes All snake venom contains enzymes. Some enzymes are protease that attack you muscles. Others are attack your hemoglobin in your blood so it will not clot. While some attack your nervous or inhibit the enzymes that make your nerves function. Every snake venom is different in how it attacks the body but all use enzymes to attack prey.

45 Aspirin- Good inhibitor When a cell is damaged, it can send pain messages along the nerves to the brain. Aspirin works by inhibiting the enzymes that carry the pain along.

46 Carbon Monoxide Poisoning Inhibits the enzyme ATP synthase that makes ATP in the mitochondria. Video!!!!

47 Different Types of Enzymes Metabolic or digestive enzymes to digest food Detergent enzymes There are over 500 enzymes in just one cell!! Needed to speed up reactions or wold be too slow!!!

48 Hydrogen peroxide (H2O2) is a poisonous byproduct of metabolism that can damage cells if it is not removed. Catalase is an enzyme that speeds up the breakdown of hydrogen peroxide into water (H2O) and oxygen gas (O2). 2H2O catalase > 2H2O + O2 REMEMBER: A CATALYST is a substance that lowers the activation energy required for a chemical reaction, and therefore increases the rate of the reaction without being used up in the process. CATALASE is an enzyme, a biological (organic) catalyst. Hydrogen peroxide is the substrate for catalase.

49 CATALASE!!! Hydrogen peroxide (H2O2) is something you can buy at the drug store. What you are buying is a 3-percent solution, meaning the bottle contains 97-percent water and 3-percent hydrogen peroxide. Most people use it as an antiseptic. It turns out that it is not very good as an antiseptic, but it is not bad for washing cuts and scrapes and the foaming looks cool. The reason why it foams is because blood and cells contain an enzyme called catalase. Since a cut or scrape contains both blood and damaged cells, there is lots of catalase floating around.bloodcells When the catalase comes in contact with hydrogen peroxide, it turns the hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2). Catalase does this extremely efficiently -- up to 200,000 reactions per second. The bubbles you see in the foam are pure oxygen bubbles being created by the catalase. Try putting a little hydrogen peroxide on a cut potato and it will do the same thing for the same reason -- catalase in the damaged potato cells reacts with the hydrogen peroxide. Hydrogen peroxide does not foam in the bottle or on your skin because there is no catalase to help the reaction to occur. Hydrogen peroxide is stable at room temperature.

50 Hydrogen peroxide is not only found at the drug store… it is also produced in the human body by cells of the immune system, for example. These cells make H2O2 to combat infection during the inflammatory process. BUT too much Hydrogen peroxide kills cells by destroying their cell membranes. In other words, H2O2 can, and does cause harm to the human body. The biochemistry of hydrogen peroxide is complex and widely researched. It is an essential molecule for our survival. However, our bodies are pretty smart; they use enzymes to keep levels under control.

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