Enzyme Activity The Digestive System

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 catalysts necessary ? 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 enzymes necessary ? 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.

Main Enzymes/Catalysts Macromolecule Products Enzyme Location Carbohydrates - Monosaccharides (Simple Sugars) - Di/Tri-saccharides Salivary amylase Mouth Pancreatic α-amylase Small Intestine Lipids - Monoglycerides - Fatty Acids Lingual lipase Bile salts Pancreatic lipase Proteins - Short Peptides - Amino Acids Pepsin Stomach Trypsin Chymotrypsin Elastase Carboxy-peptidase

Disaccharide (Carbs) Enzymes Substrate Product(s) Location Maltase Maltose Glucose Intestinal Epithelial Cells Sucrase Sucrose Fructose Lactase Lactose Galactose Answers 1. Cellulose 2. Pectin (found in the cell walls of terrestrial plants; mostly citrus fruits; gelling agent in many jams, filling, medicines etc) 3. Protein (Protease is a general term for enzymes that break down proteins) 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 -Everyone is given a puzzle piece with a written identity: lipid, protein, carbohydrate, lipase, protease, amylase. The puzzle pieces should be paired so that each substrate fits only with its corresponding enzyme…a few pieces can be included that do not fit any of the enzymes. This will represent enzymatic deficiency (Ex/ have lactose but no lactase) -Students, without talking, have to match themselves with their corresponding enzyme/substrate…a few people will have pieces that don’t fit with anyone else’s piece -Follow-up questions: 1. Keeping in mind that we are representing the enzyme/substrate relationship in the body, what are some reasons why substrates may not have a match? (A: Enzymes are specific; Enzymes may have been taken already) 2. What dictates the rate at which your ES complex was formed (A: The number of enzymes/substrates; the chance of colliding with the appropriate reactant; temperature may affect the rate by increasing energy and the chance of “colliding”) This will provide an opportunity for students to be split up into small groups for the next activity

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 -Can split the groups from the previous activity into smaller groups for this activity -Next idea is enzyme deficiencies…some of these might be presented as a result of this activity

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? -Can split the groups from the previous activity into smaller groups for this activity -Next idea is enzyme deficiencies…some of these might be presented as a result of this activity

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! Finland is most affected by congenital lactase deficiency

Lactose Intolerance Varies Worldwide

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. Importance of - Calcium: builds and maintains strong, dense bones (99% in teeth); prevents osteoporosis, neurotransmitter release, muscle contractions. Vitamin B12: DNA synthesis, cell metabolism, Fatty acid synthesis, formation of blood, normal functioning of brain and nervous system. Vitamin A: Vision, bone development, epithelial integrity, immune system Vitamin D: promotes calcium absorption, bone growth, cell growth modulation, neuromuscular function, reduction of inflammation.

Haha!

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!