Bakhrom

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Bakhrom
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13683
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Bakhrom
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2010-04-09 15:00:26
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Metabolism and nutrition
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Metabolism and nutrition
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  1. Glycogenesis
    Glucose storage. If glucose is not needed immediately for ATP production, it combines with many other molecules of glucose to form glycogen, a polysaccharide that is the only stored form of carbohydrates in our bodies. Insulin stimulates hepatocytes and skeletal muscle cells to synthesize glycogen
  2. gluconeogenesis
    The process by which glucose is formed from noncarbohydrates sources is called gluconeogenesis. Noncarbohydrates sources such as glycerol, lactic acid, and certain amino acids can be converted in the liver to glucose. Gluconeogenesis is stimulated by cortisol, the main glucocorticoid hormone of the adrenal cortex, and by glucagon from the pancreas
  3. Glycogenolysis
    The process of splitting glycogen into its glucose subunits is called glycogenolysis. When body activities require ATP, glycogen stored in hepatocytes is broken down into glucose and released into the blood to be transported to cells, where it will be catabolized by the process of cellular respiration. Stimulated by hormone Glucagon from alpha cells of pancreatic islets that breaks glycogen. The body can store about 500g of glycogen, roughly 75% in skeletal muscle fibers and rest in the liver
  4. Amino acid synthesis
    Cells throughout the body can use glucose to form several amino acids, which then can be incorporated into proteins
  5. Triglyceride synthesis
    When the glycogen storage areas are filled up, hepatocytes can transform the glucose to glycerol and fatty acids that can be used for lipogenesis, the synthesis of triglycerides.
  6. Lipolysis
    • Lipolysis is lipid catabolism.In order for muscle, liver, and adipose tissue to oxidize the fatty acids from triglycerides to produce ATP, the triglycerides must first be split into glycerol and fatty acids, a process called lipolysis. lipolysis is catalyzed by enzymes called lipases.Epinephrine and norepinephrine enhance triglyceride breakdown into fatty acids and glycerol.
    • These hormones are released when sympathetic tone increase, as occurs, for example during exercise.Other lipolytic hormones include cortisol, thyroid hormones and insulin growth factor.
  7. Lipogenesis
    Lipid anabolism.Liver cells and adipose cells can synthesize lipids from glucose or amino acids through lipogenesis, which is stimulated by insulin.lipogenesis occurs when individuals consume more calories that are needed to satisfy their ATP needs
  8. Fate of Lipids
    Oxidized to produce ATP, excess stored in adipose tissue or liver. Uses of lipids in the body:phospholipids of plasma membranes,thromboplastin for blood clotting,myelin sheaths to speed up nerve conduction,cholesterol used to synthesize bile salts and steroid hormones.lipoproteins that transport cholesterol
  9. ketone bodies
    The high rate of breakdown of fatty acids by the liver produces the ketone bodies, acetoacetate and b-hydroxybutyrate, which are released into the blood. Some of the acetoacetate is converted to acetone — another ‘ketone body’ — mainly in the lungs and this becomes noticeable on the breath
  10. Protein Metabolism
    During digestion, proteins are broken down into amino acids. After digestion, amino acids are reassembled into proteins.Proteins are not warehoused for future use.Instead, amino acids are either oxidized to produce ATP or used to synthesize new proteins for body growth and repair.Excess dietary amino acids are not excreted in the urine or feces but instead are converted into glucose(gluconeogenesis) or triglycerides (lipogenesis)
  11. The fate of proteins
    Transport of amino acids into body cells is stimulated by insulin growth factors(IGFs) and insulin. After digestion, amino acids are reassembled into proteins. Many protein function as enzymes, others are involved in transportation (hemoglobin) or serve as antibodies,clotting chemicals,hormones,contractile elements in muscle fibers,several proteins serve as structural components of the body.
  12. Protein catabolism
    A certain amount of protein catabolism occurs in the body each day, stimulated mainly by cortisol from the adrenal cortex.Proteins from worn-out cells (such as red blood cells) are broken down into amino acids.Some amino acids are converted into other amino acids.Hepatocytes convert some amino acids to fatty acids, ketone bodies or glucose.Cells throughout the body oxidize a small amount of amino acids to generate ATP via the Krebs cycle and the electron transport chain. However, before amino acids can be oxidized, they must first be converted to molecules that are part of the Krebs cycle or can enter the Krebs cycle, such as acetyl CoA.Before amino acids can enter the Krebs cycle, their amino group (NH2) must first removed-a process called deamination.Deamination occurs in hepatocytes and produces ammonia (NH3).The liver cells then convert the highly toxic ammonia to urea.
  13. Protein anabolism
    Production of new proteins by formation of peptide bonds between amino acids. Occurs on ribosomes in almost every cell.Stimulated by insulinlike growth factor (T3 and T4), thyroid hormone, insulin, estrogen & testosterone.
  14. Nonessential amino acids
    Nonessential amino acids can be synthesized by body cells. They are formed by transamination, the transfer of an amino group from an amino acid to pyruvic acid in the Krebs cycle
  15. essential amino acids
    10 are essential amino acids: they must be present in the diet because they cannot be synthesized in the body in sufficient amounts
  16. A complete protein
    A complete protein contains sufficient amount of all essential amino acids. (beef, fish, eggs).
  17. incomplete protein
    An incomplete protein does not contain all essential amino acids. Ex. of incomplete proteins are green vegetables, beans, and grains
  18. lipoproteins
    The lipid and protein combination are lipoproteins, spherical particles with an outer shell of proteins
  19. apoproteins
    The proteins in the outer shell are called apoproteins (apo).Apoproteins categorized and named according to density (ratio of lipids to proteins).
  20. Chylomicrons
    Form in small intestine mucosal epithelial cells.Transport dietary (ingested)lipids to adipose tissue for storage
  21. Very low-density lipoproteins (VLDLs)
    Made in the liver and form in hepatocytes.Transport endogenous lipids to adipocytes for storage.
  22. Low-density lipoproteins (LDLs) – “bad” cholesterol
    Carry 75% of total cholesterol in blood and deliver it to body cells for repair of cell membrane and synthesis of steroid hormones and bile salt.When present in excessive numbers, LDLs also deposit cholesterol in and around smooth muscle in arteries, forming fatty plaques that increase the risk of coronary artery disease, for this reason, the cholesterol in LDLs,is known as bad cholesterol
  23. High-density lipoproteins (HDLs) – “good” cholesterol
    Remove excess cholesterol from body cells and blood and deliver it to the liver for elimination.Because HDLs prevent accumulation of cholesterol in the blood, a high HDL level is associated with decreased risk of coronary artery disease. For this reason, HDL-cholesterol is known as Good cholesterol
  24. two sources of cholesterol in the body
    1)Present in foods (eggs, beef, pork). 2)Synthesized by hepatocytes, genetically how much your body makes the cholesterol or hepatocytes
  25. Major function of adipose tissue
    Major function of adipose tissue to remove triglycerides from chylomicrons and VLDLs and store it until needed for ATP production in other part of the body
  26. Adipose tissue
    Adipose tissue is specialized connective tissue that functions as the major storage site for fat in the form of triglycerides.Triglycerides stored in adipose tissue constitute 98% of all body energy reserves.Adipose tissue also insulates and protects various parts of the body
  27. Adipocytes
    Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat.
  28. Heat
    Heat is a form of energy that can be measured as temperature and expressed in units called calories
  29. calories (cal)
    Calories (cal)is the amount of heat required to raise the temperature of 1 gram of water 1oC. A kilocalorie equals 1000 calories
  30. metabolic rate
    metabolic rate is rate at which metabolic reactions use energy
  31. Basal metabolic rate(BMR)
    Because many factors affect metabolic rate, it is measured under standard condition, with the body in a quiet, resting, and fasting condition called the basal sate. The measurement obtained under these condition is the basal metabolic rate(BMR).
  32. core temperature
    core temperature is the temperature in the body structures deep to the skin and subcutaneous layer. The body maintains a constant core temperature near 37.0C (98.60F)
  33. Shell temperature
    Shell temperature is the temperatures near the body surface-in the skin and subcutaneous layer.Shell temperature is usually 1 to 6 degrees lower
  34. Hypothermia
    Lowering of core body temperature to 35°C (95°F)
  35. Phenylketonuria (PKU)
    Phenylketonuria (PKU) is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. Genetic error of protein metabolism that produces elevated blood levels of amino acid phenylalanine
  36. Fat-soluble vitamins
    Fat-soluble A, D, E, K; fat soluble vitamins can be stored in cells, particularly hepatocytes
  37. Water-soluble vitamins
    Water-soluble – several B vitamins and vitamin C; are not stored in cells, but instead are excreted in the urine
  38. Metabolism
    Metabolism is all the chemical reactions that occur in the body
  39. Catabolism
    Breaking down complex molecules into simple ones,generates energy (ATP),exergonic (release more energy),hydrolysis
  40. Anabolism
    Building complex molecules from simple ones,requires energy (ATP),endergonic (consume more energy than they produce),dehydration synthesis.
  41. Hydrolysis
    Hydrolysis. Catabolic reactions that break down substrates into small molecules, requires the input of water.
  42. heterotrophy
    heterotrophy is an organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition
  43. ATP
    • Adenosine triposphate.Energy transfer molecule.The Energy in an ATP molecule is stored in the bond between the phosphate groups.ATP is a nucleic acid. it include three parts:
    • 1.Sugar (ribose)2.Nitrogenous base (adenine)3.Phosphate (three of them)
  44. glycogen
    Long-term energy storage is accomplished by glycogen and fat
  45. Monosaccharides
    • – simple sugars that contains from 3 to 7 carbon atoms
    • – glucose (the main blood sugar)
    • – fructose ( found in fruits)
    • – galactose ( in milk sugar)
    • – deoxyribose (in DNA)
    • – ribose (in RNA)
  46. Disaccharides
    Disaccharides are a molecule formed from the combination of two monosaccharides by dehydration synthesis.EX: sucrose (table sugar)=glucose+fructose,lactose (milk sugar)=glucose+ galactose, maltosemaltose=glucose+glucose
  47. Polysaccharides
    Each group molecule contains tens or hundreds of monosaccaharides joined through dehydration synthesis reaction. The main polysaccharide in the human body is glycogen
  48. Glucose
    Glucose is a high energy molecule. Glucose (C6H12O6) contains six carbon atoms
  49. Oxidation
    The loss of electron(s) to another molecule which results in an overall decrease in energy content of that molecule
  50. Reduction
    The gain of electron(s) from another molecule which results in an overall increase in energy of that molecule
  51. Two coenzymes are commonly used by animal cells to carry hydrogen ion atoms
    1)NAD+ nicotinamide adenine dinucleotide 2)FAD flavin adenine dinucleotide
  52. Phosphorylation
    Phosphorylation is bond attaching 3rd phosphate group contains stored energy
  53. Three basic mechanisms an organism may use to generate ATP
    • 1.Substrate-level phosphorylation.Generates ATP by transferring a high-energy phosphate group from an intermediate phosphorylated metabolic compound(substrate) directly to ATP(process occurs in the cytosol)
    • 2.Oxidative phosphorylation removes electron from organic compounds and passes them through a series of electron acceptors, called the electron transport chain, to molecules of oxygen (O2). (this occurs in the inner mitochondrial membrane of cells)
    • 3.Photophosphorylation – electrons are raised to a higher energy level by light, passed down an electron transport chain to a final electron acceptor, and energy released during electron transfer is harnessed tomake ATP by chemiosmosis
  54. Glucose movement into cells
    Glucose absorption in the gastrointestinal tract ( and kidney tubeles) is accomplished via secondary active transport (Na+ glucose symporters). Glucose entry into most other body cells via GLuT molecules, a transporter that brings glucose into cells via facilitated diffusion.Insulin increases number of GluT, called GLuT4 transporters in the membrane of most cells.In liver & brain, always lots of GluT transporters
  55. Glucose Catabolism
    The oxidation of glucose to produce ATP is also known as cellular respiration. C6H12O6+O6----6CO2+6H2O+E
  56. four steps in cellular respiration
    • – Glycolysis
    • – Formation of Acetyl Coenzyme A - Transition Step
    • – Krebs cycle
    • – Electron transport chain
  57. Glycolysis
    Glycolysis takes place in the cytosol.It is a fundamental reaction performed by all organisms where glucose is turned into pyruvate. During glycolysis, each molecule is converted into 2 molecule of pyruvic acid. 4 ATP are produced,2 ATP need to be invested in the beginning of gylycolysis,2 NADH are produced, no need O2
  58. Transition step
    The enzyme pyruvic acid, whci is located in the mitochondrial matrix, converts pyruvic acid to a two-carbon fragment called an acetyl group by removing a molecula of carbon dioxide. The loss of molecule of CO2 by a substance is called decarboxylation. Coenzyme A (CoA) is used in transition step. Transtion step occurs only in matrix of Mitochondria, creates 2 CO2,2 NADH+H+, no ATP!!!
  59. Krebs cycle
    Acetyl group attaches to CoA, the resulting compound acetyl CoA enters the Krebs cycle. The chemical bond that attaches the acetyl group to coenzyme A (Co A) breaks, and the two-carbon acetyl group attaches to a four-carbon molecule of oxaloacetic acid to form a 6-carbon molecule called citric acid.Krebs cycle occurs in matrix of mitochondria, 4 CO2 is produced, 2 ATP is generated, 6 NADH-H+ is formed, FDAH2 is also produced.
  60. How many ATP per glucose
    38 ATP per glucose
  61. electron trasport chain
    The electron trasport chain is a series of electron carriers, integral membrane proteins in the inner mitochondrial membrane. This membrane is folded into cristae that increase surface area

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