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o. ENERGY!!!!! WHERE DOES IT COME FROM? ? ?
What do you think of when you think of a chemical reaction? Name some chemical reactions. Do you think photosynthesis and respiration are chemical reactions?
o o o What do plants need to do photosynthesis? What do they produce? What do organisms need to make ATP? What do organisms produce as a waste product? THIS ALL INVOLVES CHEMICAL REACTIONS!!!
Answer the following questions: o o o Why do you think we are studying chemical reactions? Name the parts of a chemical reaction. Name 2 chemical reactions Contrast endothermic and exothermic reactions. Look at the graphs and explain if they are endothemic or exothermic
Where is the activation Energy On the Graph?
Explain why this is a graph of photosynthesis.
Chemical Reactions Change substances into different substances by breaking and forming chemical bonds. Can you name any reactions.
Na. HCO 3(s) +HC 2 H 3 O 2(aq) =>H 2 O + CO 2(g) + Na. C 2 H 3 O 2(aq)
Chemical Equations o Needs energy to start reactions!!! REACTANTS PRODUCTS
Parts of an Equation All chemical reactions… have two parts: 1. 2. o o Reactants = the substances you start with Products = the substances you end up with The reactants will turn into the products. Reactants ® Products
Bond Energy o o o 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.
Activation Energy needed to get the reaction started. Photosynthesis: sunlight Fuel: match
o TAKES ENERGY TO GET A REACTION GOING!! Most of the time!! o What gets photosynthesis going? Where does the energy come from? Where does energy exist in the equation? o o
Exothermic and Endothermic Reactions o A reaction in which heat or more energy is produced is given out is exothermic. o A reaction in which heat is taken in or more energy is used is endothermic.
Exothermic Reactions Energy is needed to break bonds apart. Energy is released when bonds are formed. So how do exothermic reactions give out energy to the surroundings?
Exothermic reactions o o Chemical reaction where more energy is released than it absorbs Difference in energy between reactant and products. Usually heat or light. EX: Cellular respiration
Energy Level Diagrams These are drawn as graphs. They are used to show exothermic and endothermic reactions. The x axis shows time, the y axis shows energy. Energy Time
Exothermic Reactions An exothermic energy diagram looks like this. Energy reactants products Time } Energy released
Exothermic Reactions Combustion and respiration are exothermic reactions. e. g. burning methane (natural gas). CH 4 + 2 O 2 2 H 2 O + CO 2 CH 4 + 2 O 2 Energy 2 H 2 O + CO 2 Time } Energy released
ENERGY AND CHEMICAL REACTIONS Endothermic reactions o These reactions take in heat energy from their surroundings. o These cause temperatures to fall. They get cold!!!
Endothermic Reactions In these reactions, the energy required for bond breaking IS GREATER than the energy released by bond making. This means that to make endothermic reactions take place, extra energy is needed from an external source.
Endothermic reactions o o o Chemical reaction where more energy is absorbed than released. Energy must be absorbed to make up difference between reactants and products EX: photosynthesis Traps energy in bonds of glucose
Endothermic Reactions Examples are photosynthesis and most electrolysis reactions. The energy level diagrams look like this. products Energy reactants Time } Energy needed to make the reaction work.
Why are we studying chemical reactions? o o What is the name of the molecule that carries energy in your body? How does it work?
ADP, ATP and Cellular Respiration Copyright Cmassengale
Making energy! ATP The point is to make ATP! Where is the energy located?
What Is ATP? Energy used by all Cells Adenosine Triphosphate Organic molecule containing highenergy Phosphate bonds Copyright Cmassengale
Cells spend a lot of time making ATP! The point is to make ATP! What’s the point?
What Does ATP Do for You? It supplies YOU with ENERGY! Where do your cells make ATP? Copyright Cmassengale
The energy needs of life o Organisms are endergonic systems n What do we need energy for? o synthesis n o o building biomolecules reproduction movement active transport temperature regulation
Chemical Structure of ATP Adenine Base 3 Phosphates Ribose Sugar Copyright Cmassengale
How Do We Get Energy From ATP? By breaking the high- energy bonds between the last two phosphates in ATP Copyright Cmassengale
What is the Process Called? HYDROLYSIS (Adding H 2 O) H 2 O Copyright Cmassengale
How Does That Happen? An Enzyme! Copyright Cmassengale
ATP o Adenosine Triphosphate n modified nucleotide o AMP + Pi ADP o ADP + Pi ATP How efficient! Build once, use many ways high energy bonds
How does ATP transfer energy? ADP ATP O– O– O– –O P –O– P O– O O O– –O P O – + O 7. 3 energy ADP BONDS ALWAYS CONTAIN ENERGY!!! WHEN YOU BREAK A BOND ENERGY IS RELEASED!! FORMING A BOND TAKES ENERGY!! o ATP
When is ATP Made in the Body? During a Process called Cellular Respiration that takes place in both Plants & Animals Copyright Cmassengale
How Does ATP Work? o The bonds between phosphate groups can be broken by hydrolysis which produces energy!!! o ATP has 3 phosphate groups The bond to the third bond is easily broken. When the third bond is broken, energy is released. Becomes ADP – no energy!!
How is ATP Re-Made? The reverse of the previous process occurs. Another Enzyme is used! ENERGY IS ATP Synthetase NEEDED Copyright Cmassengale
The ADP-ATP Cycle ATP Synthetase ATP-ase Copyright Cmassengale
Living economy o Fueling the body’s economy n eat high energy organic molecules o food = carbohydrates, lipids, proteins, nucleic acid ATP Whoa! Hot stuff!
Activation Energy o 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.
Increase of Temperature o o o 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.
ENZYMES *A type of protein that acts as a catalyst which lowers activation energy needed to start a reaction. *They speed up reactions by weaken bonds. *Always in in -ase © 2007 Paul Billiet ODWS
What Are Enzymes? o Most enzymes are Proteins) Proteins o Act as Catalyst to accelerates a reaction o Not permanently changed in the process 51
Nothing works without enzymes! o How n important are enzymes? all chemical reactions in living organisms enzyme require enzymes to work o building n synthesis enzymes o breaking We can’t live without enzymes! n n molecules down molecules digestive enzymes speed up reactions o “catalysts” + enzyme +
How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy 53
Enzymes Without Enzyme With Enzyme Free Energy Free energy of activation Reactants Products Progress of the reaction 58
Enzymes are proteins o Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job n enzymes are named for the reaction they help n o sucrase Oh, I get it! They end in -ase breaks down sucrose o proteases breakdown proteins o lipases breakdown lipids o DNA polymerase builds DNA
Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Substrate Joins Enzyme 60
Active Site o. A restricted region of an enzyme molecule which binds to the substrate Active Site Substrate Enzyme 61
It’s shape that matters! o Lock & Key model n shape of protein allows enzyme & substrate to fit n specific enzyme for each specific reaction
Enzyme Structure o o It fits like a lock and key with its subtrate. Will not fit any other substance. How Works 1. Enzyme brings molecules close together. 2. By bonding they have weaken the bonds of the substrate so they reaction can occur quicker.
Induced Fit o. A change in the shape of an enzyme’s active site o Induced by the substrate 64
Induced Fit o. A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved). o Induced by the substrate Active Site Enzyme induced fit 65
Induced Fit Model o Enzymes can form to the shape of its substrate. http: //en. wikipedia. org/wiki/File: Induced_fit_diagram. svg Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College
What Affects Enzyme Activity? You change the shape or block active site - enzyme will not function. 1. Temperature 2. p. H levels 3. Enzyme Inhibitors 4. Activators 67
Denaturing Enzymes o o o Denaturing =- factors that change the shape. Without the correct shape enzymes won’t function properly. HOW are enzymes denatured? Temperature Animation Menu n p. H n Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College
The effect of temperature o o 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 ODWS
Temperature o Effect on rates of enzyme activity n Optimum temperature o greatest number of collisions between enzyme & substrate o human enzymes n 35°- 40°C (body temp = 37°C) Raise temperature (boiling) o denature protein = unfold = lose shape n Lower temperature T° o molecules move slower o fewer collisions between enzyme & substrate n
The effect of p. H o o o Extreme p. H 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 p. H values slightly different from the enzyme’s optimum value, small changes in the charges of the enzyme and it’s substrate molecules will occur This change in ionisation will affect the binding of the substrate with the active site. © 2007 Paul Billiet ODWS
The effect of temperature Q 10 Enzyme activity 0 © 2007 Paul Billiet ODWS 10 20 30 40 Temperature / °C Denaturation 50
p. H o Effect on rates of enzyme activity n changes in p. H changes protein shape n most human enzymes = p. H 6 -8 o depends on where in body o pepsin (stomach) = p. H 3 o trypsin (small intestines) = p. H 8
Enzymes work in different p. H o All enzymes can work in different conditions Intestines would have a lower p. H than mouth. o Look at website for examples!!!!!! o
p. H intestines trypsin What’s happening here? ! reaction rate stomach pepsin 0 1 2 3 4 5 6 p. H 7 8 9 10 11 12 13 14
Analyze the graph at what ph does Chymotrypsin function best?
The effect of p. H Optimum p. H values Enzyme activity Trypsin Pepsin 1 © 2007 Paul Billiet ODWS 3 5 7 p. H 9 11
Inhibitors b. Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the site enzyme causing the enzyme to change its shape, which in turn alters the shape active site Substrate active site altered Enzyme Noncompetitive Inhibitor 79
Enzyme Inhibitors o Inhibitors - Chemicals that bind in the active site. o Inhibitors decrease the enzyme reaction rate. o Most poisons work by affecting enzyme activity http: //en. wikipedia. org/wiki/File: Competitive_inhibition. svg Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College
Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site Substrate Competitive inhibitor Enzyme 81
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.
Aspirin - Good inhibitor o o 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.
Carbon Monoxide Poisoning o o Inhibits the enzyme ATP synthase that makes ATP in the mitochondria. Video!!!!
Different Types of Enzymes o o Metabolic or digestive enzymes to digst food Detergent enzymes There are over 500 enzymes in just one cell!! Needed to speed up reactions or wold be too slow!!!
o Place cracker in mouth!! What happens!! WHY? ? ? Would this happen with a piece of meat? o Why or why not? o
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. •
• 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.
o Hydrogen peroxide (H 2 O 2) 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 (H 2 O) and oxygen gas (O 2). o 2 H 2 O 2 ----catalase-------> 2 H 2 O + O 2 o 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.
CATALASE!!! o o o Hydrogen peroxide (H 2 O 2) 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. When the catalase comes in contact with hydrogen peroxide, it turns the hydrogen peroxide (H 2 O 2) into water (H 2 O) and oxygen gas (O 2). 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.
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 H 2 O 2 to combat infection during the inflammatory process. BUT too much Hydrogen peroxide kills cells by destroying their cell membranes. In other words, H 2 O 2 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.