DIGESTION 6.1

DIGESTION & ABSORPTION6.1The ProcessThe problem to solveMost food molecules (macromolecules) are too large to pass through your cell membrane

MacromoleculesMonomers = the smallest building blocks of the moleculePolymer = a large molecule made up of many monomers

MacromoleculesMacromolecule: Too big for absorptionMonomer: Good size for absorptionCarbohydrates polysaccharides, disaccharides, monosaccharidesmonosaccharidesLipids triglyceridesglycerol and fatty acidsProteinsamino acidsNucleic Acids DNA, RNAnucleotidesDigestion is likePlaying LEGOS

EnzymesCatalysts: A substance that speeds up the rate of a chemical reaction.How? By lowering the activation energyEnzymes: Proteins that act as biological catalysts.

Essential EnzymesRemember, enzymes dont MAKE the reaction happen, they just hold the macromolecule in its active site to help the reaction move more quickly.Enzymes1. Substratesbind to enzyme2. Substrates areconverted intoproducts3. Products arereleased

EnzymeActive Site

Enzyme -substratecomplex

2Enzymes 1st level of breakdownSourceSubstrateProductsOptimum pHAmylaseex. Salivary amylaseSalivary glandsStarch (amylose)Maltose7 (neutral)Proteaseex. PepsinStomach cellsProteins (polypeptides)Amino acids,shorter peptides3 (acidic)Lipaseex. Pancreatic lipasePancreas cellsLipidsGlycerol & fatty acids7 (neutral)PhospholipaseMany diff tissuesPhospholipidsFatty acids,glycerol,phosphatevariableEnzymesSubstrateProductsNucleaseDNA &RNAnucleotidesMaltaseMaltoseGlucoseLactaseLactoseGlucose &galactoseSucraseSucroseGlucose &FructoseExopeptidase & DipeptidasePeptides & dipeptidesAmino acidsFurther breakdownDigestive TractFood has two options: 1. Get digested and used by the body2. Be eliminated as feces

6.1.4 Diagram

Science Museum Proposal ~40 minYou have been asked to create a new exhibit for the Seoul Science Museum.

The exhibit should be a walk-through giant digestive tract with interactive features along the way.

Your exhibit will be permanently built in the science museum and has a generous budget from an anonymous donor.

Overview of the Functions of Stomach, SI, LIFunctionStomachFood is churned with the gastric juices for a period of time.Small Intestine1. In the duodenum, the food mixes with new secretions from the liver, gall bladder, and pancreas.2. Digested nutrients (monomers) pass through the villi into the circulatory system.Large Intestine1. Reabsorb the water from the food, concentrating the undigested (& unabsorbed) food into feces.2. Home to mutualistic bacteria (eg. E. coli )that keep us healthy and produce Vitamin K.

Villus: Designed for absorption & transport Digested nutrients pass through the 1-cell thick epithelium tissue to get to the circulatory system.Most molecules go to the capillary bed and then are transported through the blood.Fatty acids are absorbed into the lacteal and then are transported through the lymph.

Digested Nutrients INBlood InBlood + Nutrients OUTStarch digestion in the small intestineIllustrates many processes that we have learned aboutCatalysisEnzyme specificityMembrane permeabilityWithout a catalyst the reactions to digest starch would happen at very slow ratesStarch digestion in the small intestineIllustrates many processes that we have learned aboutCatalysisEnzyme specificityMembrane permeabilitySalivary amylase begins the digestion.Most starch digestion happens in the small intestine with enzyme secretions from the pancreas.

1,4 bonds broken by pancreatic amylaseThese small sections are now broken down into maltose and maltotrioseThree enzymes in villi membranes break the 1,6 bonds and the 1,4 products; dextrinase, maltase, glucosidaseGlucose

Starch digestion in the small intestineIllustrates many processes that we have learned aboutCatalysisMembrane permeabilityGlucose is absorbed via:co-transport with sodium ionsinto the interstitial fluid via facilitated diffusionthrough large membrane pores into capillaries.Enzyme specificityFood not absorbedIs eliminated as feces.

WaterCola, left to go flat before being put in a tubeBags made of dialysis tubingCola drinks contain a mixture of substances with different particle sizes. This cola contains glucose, phosphoric acid, and caramel (a complex carbohydrate added to produce a brown color).Predict which substances will diffuse out of the bag, with reasons for your prediction.Predict whether the bag will gain or lose mass during the experiment.