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Carbohydrate Metabolsim

Learn about how carbohydrates are digested and absorbed, the steps involved in glycolysis, the comparison between aerobic respiration and fermentation, and the possible fates of pyruvate. Understand the importance of carbohydrates in supplying energy to the body and their structural role. Explore the process of carbohydrate digestion in the mouth and small intestine, and discover the absorption of sugars. Finally, delve into the stages of aerobic respiration and the enzymes involved in glycolysis.

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Carbohydrate Metabolsim

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  1. Carbohydrate Metabolsim

  2. You will be able to… • Explain how Carbs are digested & absorbed • Draw the steps involved in Glycolysis • Compare and contrast aerobic respiration • to two different types of fermentation • Discuss the 3 possible fates of Pyruvate

  3. Mass composition data for the human body Carbohydrates don’t make the man or woman

  4. Carbs do run the man or woman: Carbohydrate recommendation is 45 to 65 percent of total calories. Sugars and starches supply energy to the body as glucose. Only energy source for red blood cells. Preferred energy source for brain & CNS

  5. Energy sources Structural molecules

  6. Salivary glands secrete saliva which contains mucus, water, ions, and amylase enzyme. Food is only briefly in the mouth, so carbohydrate digestion just begins. Starch polymers are broken down into smaller chains and into some disaccharides: maltose, sucrose, lactose.

  7. Small intestine > 3 m long, 2 to 3 cm wide. Coils, folding, & villi give surface area of 500-600 m long tube. Upper part (duodenum) most active in digestion: villi cells produce enzymes which complete digestion of carbohydrates.

  8. Plasma membrane of microvilli • use these enzymes to complete digestion: • Disaccharidases: disaccharides converted • into monosaccharide subunits. • Maltase: hydrolyzes maltose into glucose. • Sucrase: hydrolyzes sucrose into • glucose & fructose. • Lactase: hydrolyzes lactose into • glucose & galactose.

  9. Common Disaccharides: Maltose: (14) of two D-Glucose molecules Lactose  (14) Milk sugar: galactose and glucose connected Sucrose: -Glucose and -Fructose ,  (12) glycosidic linkage

  10. Small intestine’s second job: AbsorptionUses increased S.A. with folds projecting into lumen (plicae circulares), villi and microvilli. Sugars into bloodstream: Fructose diffuses into villi, glucose & galactose absorbed by active transport.

  11. Summary of carbohydrate digestion in the human body.

  12. What to do with those sugars? Turn them into ATP = Cellular respiration • Aerobic respiration • Requires molecular oxygen • Includes series of redox reactions -Anaerobic respiration *Fermentation *Does not require oxygen All are exergonic (occur spontaneously) Use a lot of coupled reactions

  13. Reaction Types in Cellular Respiration • Dehydrogenation - Hydrogens transferred to a coenzyme (an energy carrier molecule). 2. Decarboxylations - Carboxyl groups (COO-) removed from substrates as carbon dioxide (CO2). 3. Preparation reactions - Molecules rearranged in preparation for dehydrogenation or decarboxylation. 4. Phosphorylation – phosphates added to provide energy or transform molecules.

  14. Four stages of aerobic respiration Note location of each stage & amount of ATP formed Product of one stage becomes reactant of next stage

  15. Glycolysis: • Glyco = sugar • Lysis = to split • One 6 C glucose split into • two 3 C pyruvates (eventually) • Substrate • (organic molecule) Phosphorylation • of glucose occurs to make the reactions exergonic • Also stops glucose from leaving the cell.

  16. An overview of glycolysis. 6 C stages & 3 C stages Energy absorbing Energy producing

  17. Glycolysis: • energy investment • Phase: • Phosphorylation ATP kick start: Glucose turned into Fructose 1,6 bisphosphate this turns eventually into 2 glyceraldehyde-3-phosphate molecules

  18. Structural relationships among glycerol and acetone and the four C3 intermediates in the process of glycolysis. This converts into That (isomers)

  19. The two glyceraldehyde-3-phosphates • eventually turn into • two pyruvates • (with what type of rxn?) • The endproducts of glycolysis include: • 2 molecules of pyruvate • 2 molecules of NADH • 2 ATP molecules • net gain • (4 made / 2 used) • Glycolysis:E capture phase

  20. Let’s go through the steps in detail: Glycolysis animation simplistic version Glycolysis animation more detailed steps Glycolysis animation details Enzymes involved in glycolysis

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