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The Digestive System

EnzymeActivity

+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:1. Collision in a precise orientation2. 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:1. Collision in a precise orientation2. 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/CatalystsMacromolecul

eProducts Enzyme Location

Carbohydrates

- Monosaccharides (Simple Sugars)

- Di/Tri-saccharides

Salivary amylase

Mouth

Pancreatic α-amylase

Small Intestine

Lipids - Monoglycerides

- Fatty Acids

Lingual lipase

Mouth

Bile salts Small IntestinePancreatic

lipaseProteins - Short Peptides

- Amino Acids

Pepsin StomachTrypsin Small

IntestineChymotrypsi

nElastaseCarboxy-peptidase

+Disaccharide (Carbs) EnzymesEnzyme Substrate Product(s) Location

Maltase Maltose Glucose

Intestinal Epithelial Cells

Sucrase Sucrose GlucoseFructose

Lactase Lactose GlucoseGalactose

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):

1. WHAT IS YOUR ES COMPLEX?

2. GIVE ONE EXAMPLE OF AN ENZYME AND SUBSTRATE THAT CAN REPRESENT YOUR ES COMPLEX.

3. WHAT PRODUCTS ARE MADE?

4. WHERE CAN YOUR COMPLEX BE FOUND? BE SPECIFIC:- WHERE IS THE ENZYME CREATED? - WHERE IS IT SECRETED? - WHAT ARE ITS FAVOURABLE ENVIRONMETAL

CONDITIONS?

5. WHY ARE THE PRODUCTS NECESSARY FOR YOUR BODY?

6. 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!

+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.

+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!