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Enzymes Biology, Sumner HS Created by Mr. Woodbury, Modified by Mrs. Slater Enzymes Overview • Enzymes build and break bonds • Enzymes mediate anabolism (making of bonds) • Enzymes mediate digestion / catabolism (breaking of bonds) • Enzymes have specific jobs that never change • Different organisms have different enzymes that allow different functioning Tell me how... ...you would start a camp fire? Would the fire start without a “spark?” ...you would build a house? Does the lumber cut itself or nail itself together? You need energy and tools. Remind me... What happens to glucose molecules that don’t get used right away? Does it do building or breaking reactions? What happens in digestion? Does it do building or breaking reactions? Essential to life Enzymes A group of proteins that make chemical reactions (rearranging molecules) happen more easily Take less energy to start reaction Bring pieces together to be worked on Aren’t changed in the reaction Enzymes Are specific for what they do Are reusable End in -ase Amylase Lactase DNA & RNA polymerase DNA helicase Enzymes in Action Enzyme animation: http://www.lpscience.fatcow.com/j wanamaker/animations/Enzyme% 20activity.html Enzyme Functions Can help with different reactions Break covalent bonds = catabolic Build covalent bonds = anabolic Enzymes & Macros Enzymes for carbs: Sucrase breaks down sucrose / table sugar Amylase in human saliva breaks down starch Glycogen synthase builds glycogen from glucose Enzymes & Macros Enzymes for lipids: lipase breaks down fats so they can be absorbed by small intestine Enzymes for proteins: protease breaks peptide bonds between amino acids Enzymes & Macros Enzymes for nucleic acids: DNA & RNA polymerase build DNA & RNA strands DNA helicase “unzips” DNA during replication Enzyme Features Have a specific shape that fits closely to one or more specific molecules “Lock and key” model Lock = enzyme Key = substrate (what the enzyme builds or breaks) Enzyme benefits Make some reactions possible that wouldn’t happen on their own Make reactions more efficient… Less energy Happen faster We don’t give off smoke Can be reused Enzymes in a Cell • Active sites: http://highered.mcgrawhill.com/sites/0072495855/student_view0 /chapter2/animation__how_enzymes_wo rk.html • Enzyme interactions (or lack thereof) with active sites: http://www.kscience.co.uk/animations/ani m_2.htm Draw Enzyme Action 1. Choose whether your enzyme will make or break bonds 2. Make a before, during & after part of your paper 3. Before: draw the enzyme with the active site and the substance that it is going to alter 4. During: draw the enzyme interacting with the substances it is altering 5. After: draw the products & what the enzyme would look like after the reaction 6. On each drawing, label the following parts (for all that are applicable): enzyme, monomer(s), polymer, active site 7. Write a brief description of what is happening in each part 8. Identify the type of reaction: anabolic or catabolic Enzyme Action Enzyme Action Before – Description During – Description After – Description Before – Labeled Drawing During – Labeled Drawing After – Labeled Drawing Important Monosaccharides Glucose: The basic carbohydrate monomer (C6H12O6) Instant / immediate energy source Main energy transport molecule & source for metabolism All digested carbohydrates broken down to this for absorption in the small intestine. Only fuel used by the brain/nervous tissue glucose 18 More Monosaccharides You don’t need to write these… Fructose: sugar produced by fruit plants (same formula, different arrangement) Ribose: building block of DNA/RNA and ATP the “energy currency” in a cell (5 carbons). Raffinose: sugar found in beans and other vegetables, turned to intestinal gas by bacteria. 19 Other Carbohydrates Sucrose = Glucose + Fructose (a disaccharide) 20 Polysaccharides Energy source once all monosaccharides are used (still short-term energy) IF it can be digested Three types: Glycogen Starch Cellulose 21 Polysaccharides Glycogen: storage form of glucose in muscle and liver Quickly broken down to produce blood glucose; used as an energy source once glucose is used up 22 Starch vs. Cellulose vs. Glycogen 23 Polysaccharides Starch: plant storage form Food energy for us because we have the enzymes that can break those bonds 24 Polysaccharides Cellulose: plant structural form Different bond between glucose units We don’t have the enzyme to break that particular bond, but cows do. This is “fiber” (aka “roughage”) in our food. Ruminants (cows, sheep) DO have the enzymes to break that bond, so they can turn it into usable energy 25 Starch vs. Cellulose 26 Polymerization Simulation • Take the H- from one glucose molecule and –OH from another • This creates a water molecule, thus the reaction is called dehydration • When we break these bonds (metabolize our food), it requires water and is called hydrolysis • Another reason to stay hydrated! • http://bioweb.wku.edu/courses/biol115/wyatt/bioche m/carbos.htm 27 Type of Carb Example Structure Use Explanation Glucose Glycogen Starch Cellulose 28
