ENZYMES Digestive enzyme from a pitcher plant that could be used as an antibacterial agent. Picture: http://www.topnews.in/health/enzymes-carnivorous-plants-could-help-development-new-antibacterial-products-2880

What happens to the food we eat? This is going to be our driving question for the explain lesson. Since we explored lactase, the students already have an example of a digestive enzyme. Once they understand enzymes in terms of digestion, they can apply what they know to other enzymes. We think that students will probably answer these questions by saying things like it is digested or broken down. Hopefully this question will get the students to start thinking about what actually happens after they consume food. Picture: http://mcaldwellc.blogspot.com/

It breaks down into…. Carbohydrates Lipids Proteins Nucleic acids! The purpose of this slide is to get students to think about the fact that foods are made up of macromolecules and that these things react. Students should have already encountered macromolecules. In this slide you should discuss proteins, carbohydrates, and fats. Also it would be helpful if you revisited how they are made up of smaller things and those smaller things have to react with each other. This is a good chance for students to actively participate by raising their hands and recalling information about previous lessons. Picture: Carbohydrates http://biology.clc.uc.edu/courses/bio104/carbohydrates.htm http://www.medic.usm.my/~ssu/ARTICLES/article_16.htm Proteins http://www.biochem.umd.edu/biochem/kahn/bchm465-01/ribosome/proteins.html http://www.mdconsult.com/das/patient/body/130736460-2/0/10041/32858.html Fats http://hillarybio.blogspot.com/2008/09/53-lipids-incluede-fats-and-steroids.html http://money.cnn.com/galleries/2008/fsb/0804/gallery.forbidden_foods.fsb/index.html Nucleic acids!

What is lactose? Let’s look at… Lactose Lactose is a sugar found in dairy products

What do people who are lactose-intolerant lack? They lack an enzyme: LACTASE Vocab: Sugars end in “-ose” Enzymes end in “-ase” But…what is an enzyme? Get students to answer this question by drawing back on their common experience in the explore lesson. “Lactase is an enzyme that breaks lactose down into galactose and glucose. Lactase can be purchased in pill form by people who are lactose intolerant.” The explore lesson mentions that lactase is an enzyme, so they should kind of understand that. Picture: http://www.made-in-china.com/showroom/licis1/product-detailpMKQwHtdZfRN/China-Lactase.html

An enzyme is… A protein that helps molecules react with one another. It is a CATALYST! (it participates in the reaction but doesn’t change itself) This is just an informational slide. It starts out by simply defining what an enzyme does… it helps reactions occur. The question at the end of this slide is an introduction to the concept of a catalyst, which an enzyme is. This question leads the student into the next slide. The next slide will reveal that the enzyme does not change in the reaction and go on to define enzymes as catalysts. Picture: A picture we took of the box of lactaid pills when we were doing the explore lesson.

how do catalysts work? Catalysts lower the amount of energy that it takes to get a reaction started. This energy is called activation energy. In this slide, we explain in more detail what a catalyst actually does. The students know from the previous slide that an enzyme is a catalyst and that catalysts help reactions occur more efficiently. This slide just tells them more specifically how the catalysts and enzymes do achieve this. The term activation energy is introduced and an energy diagram is shown so that hopefully more visual students can see a representation of activation energy. Picture: http://www.columbia.edu/cu/biology/courses/c200507/purves6/figure06-14.jpg The picture is of an energy diagram. The top (blue) line is a reaction that is not assisted by a catalyst. The bottom (red) line is a reaction that is assisted by a catalyst. The one that is assisted by a catalyst requires less energy for the reaction to occur. YouTube

Enzymes lower the activation energy by holding molecules together. Picture: This slide is meant to get students visualizing an enzyme with its substrate(s). By thinking of the enzyme as holding the molecules in place so they can undergo the appropriate reactions, they may be able to associate enzymes with machines or objects in everyday life. A T-ball stand is a good example because it holds the ball (molecule) in place so that the bat can hit it (a reaction!). http://slanchreport.com/2009/03/03/ GOOD VIDEO that shows how the enzyme helps the reaction by holding a molecule in place. http://www.indiana.edu/~oso/animations/SN2%2BE.html

Reactions can occur without the help of catalysts, but not at the speed our body requires. Mention that enzymes bring the molecules together so they are more likely to react and that without enzymes they are just bouncing around and don’t have a good chance of reacting. DEMONSTRATION!!!! Without enzyme  Have 2 students come up front and blindfold them. Have the 2 students go to either side of the room. The students have to find one another without making noise or gestures. (No help from audience!!!) See how long it takes for them to “react”. With enzyme  Do this again, but then have one student un-blindfolded be in the middle of the room. This student has to connect the other 2 students by leading them together These students should “react” more quickly. Observe and discuss.

Each enzyme has a special place where the reaction occurs called the active site. YouTube: Enzyme Emphasize that a reaction can only take place in the active site. The molecules have to go there for the reaction to take place. Students should be getting the idea that enzymes and substrates have specific shapes. Try to get students to start thinking that way. This is a picture that we want to burn into their heads. The idea that the enzyme has an active site and the active site is where the substrate binds and when the substrate(s) bind, the reaction can take place. Use chair analogy… Picture: http://regentsprep.org/Regents/biology/units/homeostasis/lockkey.gif When a molecule needs the help of an enzyme, it goes to the active site and then the reaction takes place.

Each enzyme has a specific shape and structure that matches certain molecules. That is why we say enzymes are “specific”. Bring up “lock and key” example. Ask the students if they have a key to their house or their car. Then ask them if they can get into their neighbor’s house with their key. They will of course say no and then you can relate that to enzymes and substrates. Picture: http://www.chem4kids.com/files/bio_enzymes.html

digestive enzymes names match the foods they help react Lactase helps break down lactose. Each enzyme is specially designed to react a certain molecule Can give other examples such as maltase breaks down maltose and sucrase breaks down sucrose. Picture: http://www.eufic.org/upl/1/default/img/34.sugarcane.jpg

Each enzyme works best at a certain temperature and pH. The students may have not been exposed to pH yet. Should explain that pH is just a measure of how acidic or basic a substance is. Draw attention to the pH scale. Explain that water’s pH is neutral at about 7.0. Picture: http://trc.ucdavis.edu/biosci10v/bis10v/week1/ph.gif

What Keeps enzymes from doing their jobs? Temperature can affect an enzyme by changing its shape Talk about heat and what it can do to thing, example some things melt when they are heated. This changes the shape. Examples can be candles, plastic next to the stove, candy bar out in the sun, and ice. (Things that change shape when they are heated up.) Picture: http://4.bp.blogspot.com/_7PO1H5DLGxg/R8_26KXSdgI/AAAAAAAAADU/R4ngHh0sNeA/s320/Melting_Candle2.jpg

Changes in pH can also change an enzyme’s shape Picture: http://www.naturalhandyman.com/iip/infxtra/infmur.html In this slide, we introduce the idea that temperature is not the only thing that can change the shape of enzymes. In the next slide we elaborate on pH and the fact that enzymes work best at certain pH and temperature.

When an enzyme changes its shape it can’t do its job When an enzyme changes its shape it can’t do its job. We say it is denatured! May be helpful to break down the work “denatured”. NATURE = natural DE = not No longer has its natural shape so it can’t do what it’s supposed to do. Picture: Drawn in paint ACTIVITY: Modeling clay to show extreme environments (use modeling clay to show that extreme environments denature enzymes by moving the clay around) Have a certain shape be the enzyme and a sphere be the substrate. Then make the active site be shaped like an oval. The sphere won’t fit.

So, if changing the shape of the active site keeps the enzyme from working, what else might keep it from working? Hopefully the students will start to realize that the substrates must fit into the active site. If something is blocking the active site then the substrate can’t bind. Picture: From PowerPoint Clip Art

Lactase is just one enzyme that breaks down lactose but there are many different enzymes at work in your body. This is the point where we can begin to use the example of lactase and their new knowledge about enzymes to make them understand that enzymes are used for many things in our bodies. Picture: http://www.vhealthstore.net/oasis/images/index.2.gif http://wpcontent.answers.com/wikipedia/commons/a/ae/GLO1_Homo_sapiens_small_fast.gif

More enzymes that break things down… Sucrose = Glucose + Fructose Sucrose is table sugar! Sucrase breaks down the sugar sucrose into glucose and fructose. This picture compares sucrase to a “sugar-clipper”. Good example. Picture of Sucrase: http://www.sugars4kids.com/Horn/Sugars%204%20Kids/introd4.gif

AMYLASE: breaks down starch in your mouth and stomach LIPASE: breaks down fats Other digestive enzymes that should be discussed: Maltase breaks down maltose Amylase  breaks down starches into maltose and glucose Lipase  breaks down fats into fatty acids and monoglycerides Pepsin  MAIN GASTRIC ENZYME breaks down proteins Picture of starch http://www.partynrv.com/images/corn___taters-blue_border.jpg Picture of fat http://2.bp.blogspot.com/_M2cobFMPcGo/SYtHB-l1aII/AAAAAAAAS0M/pYc26ubVL6w/s320/fat+man+cartoon.gif Picture of protein http://www.fotosearch.com/bthumb/UNC/UNC106/u11081101.jpg PEPSIN: breaks down proteins

Every reaction in your body is helped by an enzyme Every reaction in your body is helped by an enzyme. Enzymes are the “workers” of your body. Picture: http://www.bradfitzpatrick.com/store/images/products/preview/pc015-construction-worker.jpg