1.Eunji Oh

2. 6.1.1 Explain why digestion of large food molecules is essential Many of the food we ingest (eat) have very large molecules that makes it had to cross any cell membrane Molecules must pass through the cell membranes of your intestines and through the membrane of a capillary 3. Molecule Type Molecular Form Ingested Molecular Form After Digestion Protein Protein Amino Acids Lipids Triglycerides, phospholipids Glycerol and fatty acids (phosphate) Carbohydrates Polysaccharides, disaccharides, monosaccharide Monosaccharide Nucleic acids DNA, RNA Nucleotides When we digest food molecules, we break them down (hydrolyze) into their smallest components, which can be reassembled into larger molecules (macromolecules) 6.1.1 Explain why digestion of large food molecules is essential 4. 6.1.1 Explain why digestion of large food molecules is essential 5. Example Ate an egg In the egg white (protein albumin) is an amino acid called serine Egg white albumin chemically digested, leaving serine float feely in fluid environment of small intestine Serine small enough to diffuse through small intestine small capillary blood vessel pacreas cell Build serine into protein (becomes a building block) Benefits of digesting protein albumin Serine can leave the intestine and diffuse into the bloodstream Serine availability dependent on digestion (since protein cannot be absorbed). Cell's DNA dictates final protein polymer [containing serine.] 6.1.1 Explain why digestion of large food molecules is essential 6. 6.1.2 Explain the need for enzymes in digestion Enzyme: protein molecules that act as catalysts for reactions Each digestive enzyme is specific for a specific food type Enzymes function is to lower the activation energy of the reactions o Reaction can occur with lower input of energy, which is typically in the form of heat 7. 6.1.2 Explain the need for enzymes in digestion Enzyme-catalysed reactions proceed at higher reaction rates at a lower temperature than the same reaction without an enzyme o Advantageous for living organisms o Many reactions of the digestive process would need far higher temperatures if enzymes were not involved o Humans body temperature = 37 degrees Celsius (stable) Warm enough to maintain good molecular movement With enzyme, provides enough activation energy for metabolic reactions (digestion) 8. 6.1.2 Explain the need for enzymes in digestion Digestive enzymes all help to catalyze hydrolysis reactions Amylase holds the starch in its active site Put stress on covalent bonds that bind the glucose molecule together When bonds are stressed, surrounding thermal energy provide enough molecular motion to break bonds Enzyme does not cause reaction, but just makes the reaction more likely to occur at normal temperature 9. 6.1.3 State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase. Salivary amylase Pepsin (a protease)Pancreatic lipase Source Salivary glands Stomach cells Pancreas cells Substrate Amylose (starch) Proteins (polypetptides) Lipids Products Maltose and glucoseAmino acids Glycerol and fatty acids Optimum pH Neutral (pH 7) Acidic (pH 3) Neutral (pH 7) 10. 6.1.4 Draw and label a diagram of the digestive system Mouth Esophagus Stomach Small intestine Large intestine Rectum 11. 6.1.5 Outline the function of the stomach, small intestine and large intestine Stomach o Food brought by a muscular tube called oesophagus o Food forced down to stomach by sequential series of smooth muscle contractions called peristalsis o Food held for a period of time and muscular walls of stomach churns in order to mix it with gastric juice Pepsin: a protease enzyme most active in acidic pH Hydrochloric acid (HCl): helps degrade and break down foods/ creates acidic pH necessary for pepsin to be active Mucus: lines inside of stomach wall to prevent stomach damage from HCl o Valve at lower end of stomach opens and food enters small intestine 12. http://www.youtube.com/watch? v=Uzl6M1YlU3w&feature=related 13. 6.1.5 Outline the function of the stomach, small intestine and large intestine 14. 6.1.5 Outline the function of the stomach, small intestine and large intestine Small Intestine o Duodenum: first portion of small intestine Bile from liver and gall bladder Trypsin (a protease), lipase, amylase, and bicarbonate from pancrease Inner wall made up of villi o Function is to greatly increase the surface area for absorption of molecules, such as glucose, amino acids, and fatty acids 15. 6.1.5 Outline the function of the stomach, small intestine and large intestine Each contains a capillary bed and a lacteal o Lacteal: small vessel of your lymphatic system (transport lymph fluid and immune cells) o Capillary bed: absorbs most of molecules (except fatty acids) that are taken to a wide variety of body cells by circulatory systems o Within body cell, nutrient molecule used for energy or to help build larger molecules 16. http://www.youtube.com/watch?v=yB86O2giBu8 17. 6.1.5 Outline the function of the stomach, small intestine and large intestine Large Intestine o Majority of useful nutrients are absorbed inside small intestine o Remains of original food that is undigested (much of water is still present in the remain) Leaving water in alimentary canal for a long time is beneficial because it keeps moving the food o Primary function of large intestine is water absorption o Contains a lot of naturally occurring bacteria (E.coli) Mutualistic organisms Humans provide nutrients, water, and warm environment Bacteria synthesize vitamin K and maintain healthy overall environment 18. 6.1.6 Distinguish between absorption and assimilation Assimilation is the process of bringing the nutrient to a body cell and using it as a component to help build larger molecule inside the cell (ex. Amino acids) o Food becomes part of the bodys tissue Absorption is when food molecules pass through a layer of cells such as passing through the villi 19. 6.1.7 Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion Undigested nutrients cannot pass through the villus epithelium Digested nutrients in the lumen of small intestine pass through single- cell thickness of villus epithelium to get to capillary bed or lacteal Blood from an arteriole enters the capillary bed Blood rich in nutrients leaves via a venule Entire structure creates a tremendous surface area for absorption 20. http://www.youtube.com/watch? v=UTaPUdWAEnE&feature=related 21. Citations http://en.wikivisual.com/images/3/35/Raw_egg.jpg http://image.wistatutor.com/content/nutrition/villi-in- interstine.jpeg http://www.pycomall.com/images/P/stomach.jpg http://ibhow.files.wordpress.com/2010/06/6-1-41.jpg http://2.bp.blogspot.com/_GsPuGchS5Fg/So7giHvB KCI/AAAAAAAAAIY/7gWtmgiNQ4s/s320/c8.8x13.hy drolysis.sucrose.jpg