The Digestive System Enzyme Activity
Quick Review • Can you fill in the blanks?
Outline • Review of the digestive system • What are enzymes? • Why are catalysts necessary? • Why are enzymes necessary? • Types of enzymes • Main Enzymes • Other Enzymes • Pairing and Sharing • Case Study: A Common Enzyme Deficiency
What is an enzyme? • Enzyme: A protein catalyst used by living organisms to speed up and control biological reactions • What is a catalyst? • Any substance that increases the rate of a chemical reaction due to a decrease in the free energy of the transition state, called the activation energy.
Why are catalystsnecessary ? • Most chemical reactions in cells don’t occur fast enough to support life unless a catalyst is present. • Reaction rates depend on two factors: • Collision in a precise orientation • Adequate kinetic energy to overcome electron repulsion between the atoms where the bond forms • Catalysts bring reactant molecules together. Reactant 1 + Reactant 2 Product(s)
Why are enzymesnecessary ? • Recall: Reaction rates depend on two factors: • Collision in a precise orientation • Adequate kinetic energy to overcome electron repulsion between the atoms where the bond forms (also known as the ‘Transition State’) • Enzymes bring reactants together in a precise orientation. • Enzymes lower the activation energy of a chemical reaction.
Disaccharide (Carbs) Enzymes NOTE THE WORD SIMILARITY BETWEEN ENZYME AND SUBSTRATE! What would this enzyme’s substrate be?i. Cellulase? ii. Pectinase? iii. Protease?
“Enzyme Activity” Activity • BIG IDEA: Match the substrate with its appropriate enzyme • Your Goal: You must find your matching puzzle piece. • The Rules: • Only you are to know what substrate/enzyme you are • No talking or looking at the words written on your peers’ puzzle pieces • Find your corresponding enzyme/substrate and confirm your ES complex (do your pieces fit together?) • If no, continue to look for your matching pair • If yes, go as a pair to the corner of the room which describes your ES complex
Working in Groups… • In small groups (4-5), use the available resources to research the enzyme/substrate combination you are in • Record your findings using the chart paper and markers provided…you can use words/pictures/graphical representations etc. • You will have 10 minutes to collect your ideas and then as a group will present your findings to the rest of the class
GUIDING THOUGHTS: YOU MAY INCLUDE (BUT ARE NOT LIMITED TO): • WHAT IS YOUR ES COMPLEX? • GIVE ONE EXAMPLE OF AN ENZYME AND SUBSTRATE THAT CAN REPRESENT YOUR ES COMPLEX. • WHAT PRODUCTS ARE MADE? • WHERE CAN YOUR COMPLEX BE FOUND? BE SPECIFIC: • WHERE IS THE ENZYME CREATED? • WHERE IS IT SECRETED? • WHAT ARE ITS FAVOURABLE ENVIRONMETAL CONDITIONS? • WHY ARE THE PRODUCTS NECESSARY FOR YOUR BODY? • WHAT HEALTH PROBLEMS MIGHT BE ASSOCIATED WITH A DEFICIENCY OF THIS ENZYME?
Case Study: Lactose Intolerance(aka Lactase Deficiency) • Inability to digest and metabolize lactase • Lactase • Galactose & Glucose • Found in milk and other dairy products • Symptoms: • Abdominal pain • Bloating • Irregular bowel movements • Nausea • Acid Reflux
Case Study: Lactose Intolerance(aka Lactase Deficiency) • Causes: • Primary Lactase Deficiency • Genetic • Affects adults only • Absence of a lactase persistence allele • Most common in global population • Secondary Lactase Deficiency • Injury to small intestine • Possible result from gastroenteritis, diarrhea, chemotherapy, intestinal parasites, other environmental causes • Congenital Lactase Deficiency • Autosomal Recessive genetic disorder • Lactase expression from birth prevented • Very rare • Poor Finns!
Why the symptoms? • There is an insufficient amount of lactase in the lining of the duodenum • Lactose (disaccharide) cannot be directly absorbed through the wall of the small intestine and into the blood steam • Lactose passes into the colon where bacteria can undergo metabolism • Fermentation produces copious amounts of gas (Hydrogen carbon dioxide, methane) which causes abdominal symptoms • Unabsorbed sugars and fermentation products raise osmotic pressure of the colon; there is an increased flow of water into the bowels.
Implications • Avoiding dairy products (rich in protein, calcium and carbohydrates) may decrease a person’s nutrient intake if not replaced by other products. • May experience Vitamin B12 and calcium deficiency. • Many countries fortify milk with Vit A and Vit D; Individuals must find them in other products. • Dangerous in a society that relies on feeding infants with breast milk. Soybean-derived infant formulae and lactase-free dairy products may be used as substitutes.
Ticket Out The Door On the piece of toilet paper you were given, write down 2 things you learned or found interesting in today’s lesson. Be sure to hand it in and not throw it down the toilet!