12. Nutrients and Metabolism

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  • 12. Nutrients and Metabolism

    1. 1. Nutrients and Metabolism
    2. 2. Learning Objectives <ul><li>List the six categories of nutrients. </li></ul><ul><li>List and describe the three categories of carbohydrates. </li></ul><ul><li>List and describe the four categories of lipids. </li></ul><ul><li>Give the general structure of proteins. </li></ul><ul><li>Differentiate between the water-soluble vitamins and fat-soluble vitamins and list their dietary sources and functions. </li></ul><ul><li>List the common macrominerals, microminerals and trace elements found in the body. </li></ul><ul><li>Describe the processes of catabolism and anabolism. </li></ul><ul><li>List the events that occur in each stage of cellular metabolism. </li></ul><ul><li>Describe the processes of glycolysis, the Krebs cycle, and the electron transport system. </li></ul><ul><li>Describe the general structure of enzymes and explain the role of enzymes in initiation and control of metabolic reactions. </li></ul>
    3. 3. Nutrients <ul><li>Substances derived from food; necessary for carrying out normal body functions </li></ul><ul><li>Six categories: </li></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Carbohydrates </li></ul></ul><ul><ul><li>Lipids </li></ul></ul><ul><ul><li>Proteins </li></ul></ul><ul><ul><li>Vitamins </li></ul></ul><ul><ul><li>Minerals </li></ul></ul>
    4. 4. <ul><li>Nutrients </li></ul><ul><li>Energy-producing nutrients </li></ul><ul><ul><li>Carbohydrates, fats, and proteins </li></ul></ul><ul><li>Non-energy producing nutrients </li></ul><ul><ul><li>Water, vitamins, and minerals </li></ul></ul><ul><li>Essential nutrients - ones that an animal cannot manufacture </li></ul><ul><ul><li>Must be in diet </li></ul></ul>
    5. 5. Oxygen and Water <ul><li>Oxygen - most vital requirement </li></ul><ul><li>Water - obtained by ingesting food and drink and by oxidizing protein, fat, and carbohydrates </li></ul><ul><li>Mammals consist of about 70% water </li></ul><ul><ul><li>Amount of water that is needed daily by an animal is equal to the amount of its daily energy requirement </li></ul></ul>
    6. 6. Oxygen and Water <ul><li>Almost all metabolic processes of the body involve water </li></ul><ul><li>Water serves as a lubricant for body tissues, a circulatory and transport medium, and a chemical reactant in digestion </li></ul><ul><li>Water is excreted as sweat and evaporated during panting to assist in temperature regulation </li></ul>
    7. 7. Carbohydrates <ul><li>Sugars - monosaccharides and disaccharides that come from fruits, sugar cane, honey, milk, and sugar beets </li></ul><ul><li>Starches - polysaccharides that come from grains, root vegetables, and legumes </li></ul><ul><li>Cellulose - polysaccharides that are found in most vegetables </li></ul>
    8. 8. Glucose <ul><li>Monosaccharide </li></ul><ul><li>Simplest, smallest dietary carbohydrate </li></ul><ul><li>Used to make ATP through glycolysis </li></ul><ul><li>Excess glucose is converted to glycogen (stored in liver) or converted to fat (stored in adipose tissue) </li></ul>
    9. 9. Lipids <ul><li>Insoluble in water </li></ul><ul><li>Soluble in other lipids and organic solvents </li></ul><ul><li>Four major categories: </li></ul><ul><ul><li>Neutral fats </li></ul></ul><ul><ul><li>Phospholipids </li></ul></ul><ul><ul><li>Steroids </li></ul></ul><ul><ul><li>Other lipoid substances </li></ul></ul>
    10. 10. Neutral Fats <ul><li>Composed of fatty acids and glycerol </li></ul><ul><li>Fatty acids - classified depending upon number of carbon atoms in backbone of molecule </li></ul><ul><ul><li>Long chain, medium chain, short chain </li></ul></ul><ul><li>Glycerol is a modified simple sugar </li></ul>
    11. 11. Neutral Fats <ul><li>Triglycerides - three chains of fatty acid molecules attached to a single molecule of glycerol </li></ul><ul><li>Saturated fats - fatty acids with single bonds between carbon atoms; full complement of hydrogen </li></ul>
    12. 12. Neutral Fats <ul><li>Unsaturated fats - one or more double bonds between the carbon atoms; not a full complement of hydrogen atoms </li></ul><ul><ul><li>Monounsaturated and polyunsaturated </li></ul></ul>
    13. 13. Neutral Fats <ul><li>Liver can convert one fatty acid to another </li></ul><ul><ul><li>Essential fatty acids - cannot be synthesized </li></ul></ul><ul><ul><li>Linoleic acid, lino leni c acid, and arachidonic acids </li></ul></ul><ul><li>Neutral fats contain over twice as much potential energy by weight as protein or carbohydrates </li></ul>
    14. 14. Neutral Fats <ul><li>Aid absorption of the fat-soluble vitamins A, D, E, and K </li></ul><ul><li>Stored subcutaneous fat is an important insulator </li></ul><ul><li>Fat surrounds and cushions vital organs such as the heart, kidneys, and eyes </li></ul>
    15. 15. Phospholipids <ul><li>Modified triglycerides derived primarily from cell membranes of plant and animal cells </li></ul><ul><li>Glycerol core and two fatty acid chains </li></ul><ul><li>Phosphorous group attached to the glycerol molecule; “polar head” </li></ul>
    16. 16. Steroids <ul><li>Composed of four flat interlocking rings of hydrocarbons </li></ul><ul><li>Include cholesterol, bile salts, sex hormones and hormones released from the cortex of the adrenal gland </li></ul><ul><li>All of the other steroid molecules can be made from cholesterol </li></ul><ul><li>Cholesterol is found in the plasma membrane </li></ul><ul><li>Liver is able to manufacture cholesterol </li></ul>
    17. 17. Other Lipoid Substances <ul><li>Fat soluble vitamins </li></ul><ul><li>Eicosanoids - regulatory molecules derived from arachadonic acid </li></ul><ul><ul><li>Prostaglandins, leukotrienes and thromboxanes </li></ul></ul><ul><li>Lipoproteins </li></ul>
    18. 18. Protein Functions <ul><li>Primary structural material of the animal body </li></ul><ul><li>Regulate body functions - enzymes and hormones </li></ul><ul><li>Transport oxygen - hemoglobin </li></ul><ul><li>Aid in body movement - contractile proteins in muscle cells </li></ul>
    19. 19. Protein Structure <ul><li>Composed of amino acids </li></ul><ul><ul><li>Amine group (-NH2) </li></ul></ul><ul><ul><li>Organic acid group (-COOH) </li></ul></ul><ul><ul><li>“ R” group - variable </li></ul></ul><ul><li>22 different types of amino acids </li></ul>
    20. 20. Protein Structure <ul><li>Peptide bond - forms between acid group from one amino acid and basic group on the next </li></ul><ul><li>Polypeptide - more then ten amino acids bonded together </li></ul><ul><li>Protein - 50 or more amino acids </li></ul>
    21. 21. Protein Structure <ul><li>Proteins can be composed of 100 to 10,000 amino acids </li></ul><ul><li>Type and order of amino acids determines structure and function of the protein </li></ul>
    22. 22. Essential Amino Acids <ul><li>Must be present in the diet </li></ul><ul><li>Animal either cannot make them at all or cannot make them fast enough to meet the body’s needs for tissue maintenance and growth </li></ul>
    23. 23. Nitrogen Balance <ul><li>Amino acids not used to make protein are used by the cell to make energy or converted to carbohydrates or fats. </li></ul><ul><li>Positive nitrogen balance - body is incorporating more protein into tissues than it is using to make energy (ATP) </li></ul><ul><li>Negative nitrogen balance - occurs when protein breakdown exceeds the amount of protein being incorporated into tissues </li></ul>
    24. 24. Vitamins <ul><li>Function as co-enzymes or parts of co-enzymes or regulatory molecules </li></ul><ul><li>Most vitamins are not made in the body and must be consumed in the diet </li></ul><ul><ul><li>Exceptions: Vitamin D, made in the skin; vitamin K and biotin, made in the intestine by bacteria; beta carotene can be converted into vitamin A </li></ul></ul>
    25. 25. Water-Soluble Vitamins <ul><li>Absorbed through the GI tract wall when water is absorbed </li></ul><ul><li>Excesses excreted in urine; toxicities are rare </li></ul><ul><ul><li>Vit B1 (thiamine) </li></ul></ul><ul><ul><li>Vit B2 (riboflavin) </li></ul></ul><ul><ul><li>Vit B3 (niacin or nicotinamide) </li></ul></ul><ul><ul><li>Vit B5 (pantothenic acid) </li></ul></ul><ul><ul><li>Vit B9 (folacin or folic Acid) </li></ul></ul><ul><ul><li>Vit B12 (cyanocobalamin) </li></ul></ul><ul><ul><li>Vit C (ascorbic Acid) </li></ul></ul>
    26. 26. Fat-Soluble Vitamins <ul><li>Bind to ingested lipids before they are absorbed with ingesta </li></ul><ul><li>Stored for long periods of time in tissues; toxicity a possibility if high levels are consumed </li></ul><ul><ul><li>Vit A (retinol) </li></ul></ul><ul><ul><li>Vit D (antirachitic factor or calciferol) </li></ul></ul><ul><ul><li>Vit E (antisterility factor or tocopherols) </li></ul></ul><ul><ul><li>Vit. K (coagulation factor or quinones) </li></ul></ul>
    27. 27. Minerals <ul><li>Inorganic substances; non energy-producing </li></ul><ul><li>Macrominerals - calcium, chlorine, magnesium, phosphorus, potassium, and sodium </li></ul><ul><li>Microminerals - copper, iodine, iron, manganese, selenium and zinc </li></ul><ul><li>Trace elements - chromium, cobalt, fluorine, molybdenum, nickel, silicon, sulphur and vanadium </li></ul>
    28. 28. Cell Metabolism <ul><li>Catabolism - involves breakdown of nutrients into smaller molecules to produce energy </li></ul><ul><li>Anabolism - use of stored energy to assemble new molecules from the small components that are produced from catabolism </li></ul>
    29. 29. Catabolism <ul><li>Three stages: </li></ul><ul><li>Stage 1 - digestion in lumen of the gastrointestinal tract </li></ul><ul><li>Stage 2 - anaerobic respiration in cytoplasm of cells </li></ul><ul><li>Stage 3 - aerobic respiration in mitochondria of cells </li></ul>
    30. 30. Catabolism - Stage 1 <ul><li>Hydrolysis: </li></ul><ul><li>Carbohydrates broken down to monosaccharides </li></ul><ul><li>Proteins broken down to amino acids </li></ul><ul><li>Nucleic acids broken down to nucleotides </li></ul><ul><li>Fat broken down to fatty acids and glycerol </li></ul>
    31. 31. Catabolism - Stage 1 <ul><li>Once hydrolysis is complete, nutrient molecules are absorbed by cells that line the small intestine. </li></ul>
    32. 32. Catabolism - Stage 1 <ul><li>Transferred to capillaries and extracellular spaces deeper in the wall of the intestine </li></ul>
    33. 33. Catabolism - Stage 2 <ul><li>Anaerobic respiration: </li></ul><ul><li>Nutrients catabolized to produce acetyl-CoA </li></ul><ul><li>Transported through the cytoplasm to the mitochondria, where it is used in stage 3 of catabolism </li></ul>
    34. 34. Catabolism - Stage 3 <ul><li>Aerobic respiration: </li></ul><ul><li>Involves attachment of an inorganic phosphate group (PO 4 ) to a molecule of adenosine diphosphate (ADP) to a form of adenosine triphosphate (ATP) </li></ul>
    35. 35. Anabolism <ul><li>Biosynthetic processes </li></ul><ul><li>Cells use ATP to manufacture substances and perform vital functions </li></ul><ul><li>Dehydration synthesis - opposite of hydrolysis </li></ul>
    36. 36. Summary: Catabolism and Anabolism
    37. 37. Control of Metabolic Reactions <ul><li>Metabolism is a multienzyme sequence of events </li></ul><ul><ul><li>Product of one step is the substrate of the next </li></ul></ul><ul><li>Activity depends on molecular shape of enzyme </li></ul><ul><li>Active site - region of the enzyme that binds to the substrate </li></ul><ul><li>Catalysts - speed up reactions by lowering the activation energy </li></ul>
    38. 38. Control of Metabolic Reactions <ul><li>Cofactors: nonprotein substances </li></ul><ul><li>Examples: iron, zinc, copper </li></ul><ul><li>Function with enzymes to complete the shape of a binding site </li></ul>
    39. 39. Control of Metabolic Reactions <ul><li>Coenzymes: nonprotein organic substances </li></ul><ul><li>Vitamins or derived from vitamins </li></ul><ul><li>May be bound temporarily or permanently to the enzyme </li></ul>
    40. 40. Energy for Metabolic Reactions <ul><li>Storage forms of energy: ATP, NADH, and FADH 2 </li></ul><ul><li>Energy released when molecular bonds are broken </li></ul>
    41. 41. Carbohydrate Metabolism <ul><li>Glycolysis </li></ul><ul><li>Occurs in cytoplasm </li></ul><ul><li>Anaerobic </li></ul><ul><li>Glucose broken down to form pyruvate (pyruvic acid) </li></ul><ul><li>Pyruvate transported to mitochondria </li></ul>
    42. 42. Carbohydrate Metabolism
    43. 43. Carbohydrate Metabolism <ul><li>Cellular Respiraton </li></ul><ul><li>Krebs Cycle & Electron Transport Chain </li></ul><ul><li>Aerobic </li></ul><ul><li>Occurs in mitochondria </li></ul>
    44. 44. Krebs Cycle
    45. 45. Electron Transport Chain
    46. 46. Summary of Energy Production From One Glucose Molecule
    47. 47. Lipid Metabolism <ul><li>Triglycerides hydrolyzed into glycerol and three fatty acid chains </li></ul><ul><ul><li>Glycerol further catabolized to acetyl-CoA </li></ul></ul><ul><ul><li>Fatty acid chains fragmented (beta-oxidation) </li></ul></ul><ul><ul><li>Some are then converted into ketones </li></ul></ul>
    48. 48. Protein Metabolism <ul><li>Amino acid catabolism occurs in most tissues </li></ul><ul><li>In intestinal mucosa, kidney, brain, liver, and skeletal muscle, amino acid molecules may undergo deamination or transamination . </li></ul>
    49. 49. Transamination <ul><li>Amine group (--NH 2 ) is transferred to another carbon chain to form a different amino acid </li></ul><ul><li>Newly constructed amino acids then diffuse into the surrounding cytosol </li></ul>
    50. 50. Deamination <ul><li>Amine is removed from the carbon chain and becomes an ammonia molecule. </li></ul><ul><ul><li>Liver enzymes convert ammonia to urea (excreted in urine) </li></ul></ul><ul><li>The carbon chain is metabolized further to yield ATP </li></ul>

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