Nature’s Efficiency Experts Enzymes Nature’s Efficiency Experts

What are Enzymes? Enzymes are a special group of PROTEINS Remember proteins are responsible for structure and function They are referred to as CHEMICAL CATALYSTS because they control chemical reactions without becoming a part of them. The enzyme itself is not changed in the REACTION and can be used again and again.

Examples of Enzymes Most enzymes names end with –ase. Usually they are named for the material they are acting upon… Lactose is digested by lactase Sucrose is digested by sucrase Cellulose is digested by cellulase and so on… What exactly does “digestion” mean? To break bonds between monomers in a large polymer through enzyme activity!

OH, GEEZE,Not this…again! C o n d e s a t i HYDROLYSIS = DIGESTION BREAKING DOWN CONDENSATION = SYNTHESIS BUILDING BOTH REQUIRE ENZYMES!

Enzyme Control: Digestion There are over 4000 biochemical reactions that are controlled by enzymes… Digestion: Amylase digests carbohydrates into monosaccharides. Amylase is in saliva. There are 7 digestive enzymes.

Enzyme Control: toxic by-products Toxic By-products: Biochemical reactions often produce substances that can be toxic to cells. Enzymes digest them into substances that are not harmful. The enzyme catalase digests hydrogen peroxide(H2O2) into H2O and O2. BTW: Not a good idea to use peroxide on boo boo’s. The enzyme reaction kills bacteria, but, it also kills healthy cells too which means healing slows!

Enzyme Control: poisons/products Poisons: Act as enzyme inhibitors; they prevent enzymes from working. Examples like Raid(animals) and Round-Up(plants). They kill certain kinds of organisms without harming others because they act on enzymes that are specific to them. Many animal toxins like snake venom do the same thing. Products ‘Biological’ stain or spill cleaners Meat tenderizers(think about it!)

How enzymes work Enzymes are chemically and structurally matched to the biomolecule they digest(or build)… In much the same way that a key fits a lock, in fact this “lock and key” analogy is often used to describe enzyme activity. Let’s see why…

“Lock and Key” Model It is important to note that this reaction can run in the opposite direction…to build polymers. However, a different enzyme is used and are called polymerases. Sucrose Glucose Fructose Lock and Key Enzyme changes Shape and by heat and friction the bond is broken Once bond is broken products are released enzyme continues to work as long as substrate is present Sucrase

Why are enzymes so important? Because Nature Loves Efficiency! In order for all of the activities of life to occur; all the chemical reactions, building and breaking down of macromolecules, repair and maintenance of structures…If cells had to wait around for these materials and reactions to occur spontaneously…life would not be possible! Also, needless to say all of those activities require a great deal of energy to get started, or keep going, or stop!…so much so that those little mitochondria would not be able to produce enough ATP fast enough to fuel everything a cell has to do…again life would not be possible! Enzymes get the job done without the cell having to expend the energy to do it! In other words they lower the activation energy of chemical reactions so they go faster and result in more product!!!!

How can we visualize an enzyme reaction? NO Enzyme: High activation energy Longer time Less Product With Enzyme: Less activation energy Less Time More Product MORE EFFICIENT! SUNSCREEN

How can we visualize an enzyme reaction? NO Enzyme: High activation energy Longer time Less Product With Enzyme: Less activation energy Less Time More Product MORE EFFICIENT!

Concentration of Substrate So…What happens if I eat this huge pizza? You might think a lot more enzyme will be produced to take care of this “extra large” digestion issue…and you’d be right, to a point… Enzyme-substrate reaction rate depends upon open activation sites; enzyme production takes time…so, once all available enzymes are in use, digestion can actually slow and reach a plateau. So, eating a lot-all at once-can actually slow digestion down…mom is right, slow down and chew your food smaller pieces means enzymes can digest their substrates faster!

Enzymes can be altered … Enzymes are very sensitive to their environment Any change can result in an enzyme that will not work effectively, or, not at all…at that point the enzyme is said to be denatured.

temperature Any increase or decrease in the temperature at which the enzyme functions changes the shape of the activation site. Just like when heating wax causes it to fold and bend. If the activation site changes shape then the “key” no longer fits the “lock” and the reaction stops. This is why food doesn’t ‘digest’ well when you have a high fever, and …..well, you better be real close to a toilet!

pH changes Any increase or decrease in pH can denature an enzyme. pH is the measure of how acidic or basic a substance is Intestinal enzymes work best in neutral-basic environments Stomach enzymes, like pepsin, are designed to work best at a low pH(high acid) When you have an invasion of nasty food borne bacteria, their metabolism neutralizes your stomach pH, your enzymes denature, and, again… where’s that toilet!

Genetic mutation Since enzymes are proteins; their manufacture depends upon a correct amino acid sequence, and since that is determined by DNA, mutation can change the “nature” of a protein. Lactose intolerance is caused by a mutation. Folks with this mutation produce ineffective lactase, i.e. the shape of the “lock” is changed because the amino acids are incorrect; as a result they cannot properly digest milk sugar. If they eat dairy, the sugar is fermented by intestinal bacteria doing their anaerobic thing and, oh gosh… Where’s that toilet again! Lactase in a box!

COLOR PIECES USING ANY 3 COLORS DO NOT COLOR THE ENZYME