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Flashcards

Nutritional Biochemistry NMDF221 Revision Final Exam Sessions 1-4

Eleni Cico Naturopathy Inglês 139 flashcards

Flashcards do conjunto (139)

  1. 1Name three major groups of carbohydrates?Monosaccharide’s, disaccharides or oligosaccharides and polysaccharides
  2. 2Give two examples of each of these groups of carbohydrates?. Fructose, galactose, glucose / lactose, maltose, sucrose / cellulose, glycogen,
    starch
  3. 3Which monosaccharide has a slower rate of uptake from the digestive tract?Fructose
  4. 4The digestion of disaccharides occurs mainly in which location?Upper small intestine
  5. 5The digestive enzymes which achieve this are collectively known as ………Disaccharidases
  6. 6What is the name of the key enzyme involved in the breakdown of polysaccharides?Alpha amylase (glycosidase)
  7. 7Which two places is this enzyme produced?Mouth and pancreas
  8. 8By which transport mechanism are monosaccharide’s taken over the basolateral border and into portal circulation?Facilitated diffusion
  9. 9Glucose is up taken into cells via ………Glucose transporters (GLUT)
  10. 10What is the name of the transporter which is regulated by insulin?GLUT 4
  11. 11In which locations are GLUT4 found?Muscles and adipose tissue
  12. 12Which three nutrients are required for the insulin receptor to function?Chromium, glutamine and B3
  13. 13What is the name of the transporter in the brain?GLUT 3
  14. 14Name two groups of simple lipids?.Fatty acids, glycerols (triacylglycerols, diacylglycerols and monoacylglycerols)
    and waxes such as sterols esters (cholesterol) and nonsterol esters (Vit A)
  15. 15Name two groups of compound lipids?Phospholipids (phosphatidic acids, plasmalogens and sphingomyelins),
    glycolipids (CHO containing) and lipoproteins
  16. 16.How are long-chained fatty acids assisted over the brush border and explain how this is accomplished?Dietary fats with the help of enzymes (lipases) are hydrolyzed and bile salts help
    in emulsification and form micelles which are stabilized to allow the hydrophobic
    fats to diffuse through the hydrophilic brush border of intestine.
  17. 17How are LC FAs transported through the enterocytes?via chylomicrons
  18. 18How do these larger lipids then travel through circulation and why are these necessary?via lipoproteins such as VLDL’s, LDL’s and HDL’s, as the protein component
    stabilize the lipoproteins as they travel through the blood and allow them to be
    recognized by specific cell receptors
  19. 19Which enzyme hydrolyses these particles, allowing the lipids to be released into tissues?Lipoprotein lipase
  20. 20How do short chained fatty acids travel through circulation?Bound to albumin
  21. 21What is the major storage site for triaclyglycerols?Adipose tissue
  22. 22What effect can insulin have on these stores?Insulin accelerates the entry of glucose into the adipose cells and increases the
    availability and uptake of fatty acids by stimulating lipoprotein lipase. It also
    inhibits intracellular lipase which hydrolyses stored triacylglycerols.
  23. 23Name four essential and four non-essential amino acids?ESSENTIAL - Isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
    tryptophan, valine; NON-ESSENTIAL – Alanine, aspartic acid, carnitine,
    cysteine, glutamic acid, glutathione, glycine, ornithine, praline, serine, taurine,
    tyrosine
  24. 24Which are absorbed faster – peptides or free amino acids?.Peptides
  25. 25What two mechanisms are utilised to transport free amino acids across the basolateral border? What reason may designate the use of one transport over the other?.Sodium dependent pathways are used when the amino acid concentrations in
    the gut are low, while diffusion is the mechanism at other times.
  26. 26Within intestinal cells, amino acids may be used for the synthesis of what four compounds?Apoproteins for lipoprotein formation, new digestive enzymes, hormones or
    nitrogen-containing compounds
  27. 27What group of enzymes hydrolyse protein?Proteases
  28. 28.Name three types of protein hydrolyzing enzymes that function in the small intestine?Trypsinogen/ trypsin, chymotrypsinogen/ chymotrypsin, procarboxypeptidases
    such as carboxypeptidase A & B, proelastase/ elastase, collagenase,
    ribonuclease and deoxyribonuclease
  29. 29What syndrome allows small oligopeptides to enter circulation via paracellular or intercellular routes, which can cause inflammatory reactions?Leaky gut
  30. 30Name two carrier systems which transport amino acids into the liver?.Diffusion; sodium dependent transport; hormones and cytokines or system A
    which induces glucagon and provides amino acid substrates for glyconeogenesis
  31. 31Name 3 types of plasma proteins?Albumin, transthyretin, retinol-binding protein, blood-clotting proteins or globulins
  32. 32Name three nitrogen-containing compounds which the liver synthesizes from amino acids?Glutathione, carnitine, creatine, carnosine and choline
  33. 33Name two forms of vitamin C, one acid and one alkaline?ACID – ascorbic acid; ALKALINE – calcium ascorbate or sodium ascorbate
  34. 34What substance is necessary to reform ascorbate from dehydroascorbate and is essential for vitamin C metabolism?Glutathione
  35. 35Is the absorption of vitamin C influenced by intake concentrations?Yes
  36. 36Name 2 antagonists of vitamin C?Pectin, zinc and high intakes of iron
  37. 37Which cells have the highest concentration of vitamin C?Adrenal and pituitary glands
  38. 38Vitamin C is necessary to activate which enzyme responsible for energy production and collagen synthesis?Hydroxylase
  39. 39Name two co-enzyme forms of thiamine?Thiamine diphosphate (TDP) and thiamin triphosphate (TTP)
  40. 40Name three foods which contain anti-thiamine factors?Raw fish and polyhdroxyphenols such as found in coffee, tea, betel nuts,
    blueberries, black currents, Brussels sprouts and red cabbage
  41. 41.Name two substances which prevent the destruction of vitamin B1?Vitamin C and citric acid
  42. 42What are the group of enzymes which break the phosphate bonds with thiamine prior to absorption?Phosphatases
  43. 43In high concentrations of B1 ingestion, by what mechanism does transport over the brush border occur?Passive diffusion
  44. 44.By what mechanism does the uptake of B1 occur into cells?Active transport (sodium dependent)
  45. 45What are the two co-enzyme forms of riboflavin?FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide)
  46. 46Name three antagonists of vitamin B2?Copper, zinc, iron, manganese and alcohol
  47. 47Which protein carrier transports majority of B2 through circulation?Albumin
  48. 48The highest concentrations of B2 exist in which organs?Liver, kidney and heart
  49. 49Name the two active coenzyme forms of niacin?NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine
    dinucleotide phosphate
  50. 50Vitamin B3 may also be synthesized in the liver from which amino acid?Tryptophan
  51. 51By which two mechanisms do B3 get absorbed from the intestine?Passive diffusion or sodium dependent active transport dependent on intakes
  52. 52Is the absorption of mechanism of B5 concentration dependent?Yes
  53. 53What is the coenzyme form of pantothenate?Coenzyme A
  54. 54How is B5 mainly transported in circulation?via red blood cells
  55. 55In cells what is B5 typically used for?To synthesize and re-synthesize CoA
  56. 56Name the three phosphorylated coenzyme forms of pyridoxine?PNP (pyridoxine phosphate), PLP (pyridoxal phosphate) and PMP (pyridoxamine
    phosphate)
  57. 57These phosphorylated forms require hydrolysis prior to absorption into the enterocytes, what is the name of the enzyme responsible for this and which nutrient is it dependent on?Alkaline phosphatase which is zinc dependent
  58. 58What is the active form of B6 known as?Pyridoxal-5-phosphate (PLP)
  59. 59Which vitamin is an agonist of B6?B2
  60. 60How is B6 absorbed across both the brush and basolateral border?Passive diffusion
  61. 61How is B12 released from peptide bonds in foods?Pepsin and hydrochloric acid
  62. 62What is the name of the substance which is found in saliva and gastric juice that can bind to B12 before it is released from food?R proteins
  63. 63What is the name of the glycoprotein synthesized by the gastric parietal cells, although functions in the small intestine to aid B12 absorption?IF (intrinsic factor)
  64. 64Describe the process by which these two substances aid B12 digestion?B12 in stomach binds with R-proteins and travel to intestine, once in the SI, the
    B12- R protein complex is hydrolysed by proteases to release the B12. After, it is
    released then binds to IF where this complex then travels to the ileum, where
    specific B12 receptor sites (ileal receptor) are located and calcium helps in
    absorption at ileal receptors.
  65. 65Which mineral is required for B12 absorption?Calcium
  66. 66Which 2 nutrients may antagonize B12 if supplemented at the same time?Vitamin C and iron
  67. 67What is the major storage form of B12 in the liver?Adenosylcobalamin
  68. 68B12 travels in circulation bound to what?Transcobalamins
  69. 69What are the three substances which make up folic acid?Pteridine, PABA (para-amino-benzoic acid) and glutamic acid
  70. 70Folate exists primarily in foods in polyglutamate forms which need to be hydrolysed into monoglutamate forms prior to absorption into enterocytes. Name the group of enzymes responsible for this and what nutrient are they dependent on?Conjugases are zinc dependent
  71. 71Name 3 factors which may inhibit the absorption of folate?Alcohol, zinc deficiency due to diminished conjugase activity or conjugase
    inhibitors such as lentils, legumes, cabbage and oranges
  72. 72.How does the majority of folate travel through circulation?Bound to folate binding proteins (FBP’s)
  73. 73Where is biotin endogenously produced?Colonic bacteria
  74. 74What substance can inhibit intestinal absorption of biotin?Raw egg white or alcohol
  75. 75Name three forms of vitamin A?Retinol, retinal, retinoic acid, retinyl ester and provitamin A carotenoids such as
    β-carotene, α-carotene, lycopene and oxy-carotenoids such as lutein,
    canthaxanthin and zeaxanthin
  76. 76How does the absorption of vitamin A take place over the brush border?Active transport via micelle
  77. 77Inside cells, which two proteins are required for vitamin A metabolism?CRBP (cellular retinoid binding protein) and CRABP (cellular retinoic acid binding
    protein)
  78. 78Inside the enterocyte, which B vitamin is needed to form retinol from beta carotene?Niacin
  79. 79Name two substances which may enhance vitamin A absorption?Fat and vitamin E
  80. 80Name two substances which may impair the absorption of vitamin A?Fiber and vitamin E in large doses
  81. 81Describe the process by which vitamin D can be synthesized by sunlight and subsequently transported to tissues?Skin exposure to UV light in the presence of 7-dehydrocholesterol, a derivative
    of cholesterol, produces pre-vitamin D3. This is then converted to vitamin D3,
    also known as cholecalciferol or calcitriol, which is reabsorbed into the blood
    stream and transported to tissues via plasma transporter α2-globulin vitamin Dbinding protein (DBP).
  82. 82.Via what other mechanism can vitamin D be transported to tissues?Chylomicrons
  83. 83Name two substances which can stimulate vitamin D metabolism?PTH (parathyroid hormone), low calcium or low phosphorous
  84. 84Name the two classes of vitamin E?Tocopherols and tocotrienols
  85. 85Once over the basolateral border, how is vitamin E transported to the liver?Via the chylomicron remnants
  86. 86How is vitamin E mainly transported through circulation, after leaving the liver?via lipoproteins VLDL, LDL and HDL’s
  87. 87What is thought to be vitamin E’s main function in these particles?May prevent them from oxidation
  88. 88Where does vitamin E exist mainly in cells?Within cell membranes
  89. 89.Name 2 types of vitamin K, one exogenous and one endogenous type and from where are they found or produced?Phylloquinone (K1) exists in plants; menaquinone (K2) is synthesized by colonic
    bacteria
  90. 90What is a known antagonist of vitamin K?Warfarin
  91. 91How is vitamin K transported over the basolateral border?Active transport via chylomicrons
  92. 92For what reason is the calcium present in foods and supplements relatively insoluble?As calcium is present in its insoluble salts and need to be solubilised
  93. 93Via which binding sites does calcium get up taken over the brush border?Calbindin (calcium-binding protein)
  94. 94What happens to these when there is low blood levels of calcium? Which vitamin regulates this process?Calbindin transporters up regulate or increase in number, to draw in more
    calcium from the intestines
    Vitamin D
  95. 95Name three substances which may bind calcium to be excreted in faeces?Fibre, phytate, oxalate and fatty acids
  96. 96.List two factors which may increase the absorption of calcium?Food ingestion, lactose, other sugars, sugar alcohol and protein
  97. 97List four factors which may inhibit calcium absorption?Fibre and phytates bind calcium; oxalates chelate and increase excretion;
    magnesium competes for absorption with calcium; parathyroid insufficiency will
    decrease vitamin D absorption which decreases calcium absorption; unabsorbed
    fatty acids in high quantities bind to calcium and form fatty soaps
  98. 98List three factors which decrease the absorption of magnesium?Phytates and fibre decrease absorption; unabsorbed fatty acids binds to form
    soaps which are then excreted; iron and magnesium supplementation taken
    together decreases magnesium uptake
  99. 99List two factors which may increase magnesium absorption?Vitamin D increases absorption through active transport; lactose also
    appears to increase absorption
  100. 100What are the two mechanisms of magnesium absorption and why would one method be utilised over another?Concentration dependent passive diffusion with high intakes and carrier
    mediated active transport at low intakes
  101. 101List two ways that magnesium may travel through circulation?Free Mg2+; protein bound albumin or globulins; non-protein complexes to
    citrate, phosphate or sulphate.
  102. 102What are the two mechanisms of phosphorus absorption and why would one method be utilised over another?Concentration dependent passive diffusion with high intakes and carrier
    mediated sodium dependent active transport at low intakes
  103. 103In what form is phosphorus usually found in the body?PO4
    2+
  104. 104List two ways sodium is up taken into enterocytes?Sodium/ glucose transporter; sodium/ hydrogen exchange or sodium
    channel
  105. 105How is chromium mainly transported through circulation?Bound to transferrin
  106. 106Name two other minerals which competitively bind to transferrin?Copper, cadmium, manganese and iron
  107. 107Which vitamin increases the plasma concentration of chromium?Vitamin C
  108. 108In foods, copper is bound to proteins. What is needed to free bound copper to allow its absorption?HCl and pepsin in the stomach and proteases in the small intestine.
  109. 109What is the name of the receptors which facilitate the transport of copper into cells from circulation?Ceruloplasmin receptors
  110. 110What is the name of the soluble intracellular proteins which bind to intracellular copper and deliver it to various locations in the cell?Chaperones
  111. 111Name three factors which decrease copper absorption?Zinc, phytates, iron in large amounts, calcium and phosphorus, vitamin C
    and antacid ingestion due to these preventing copper being released from it’s
    bound amino acids
  112. 112Name an iodine inhibitor?Goitrogens (isothiocyanates) found in the cruciferous family of vegetables
    which include broccoli, kale, cauliflower, mustard, turnips, Brussels sprouts,
    cabbage etc
  113. 113Which mechanism is utilised to allow iodine to enter and exit the enterocytes?simple diffusion
  114. 114How is iodine up taken into the thyroid?active transport
  115. 115Name two transport proteins which transport the thyroid hormones T3 and T4 through circulation?Thyroxine binding globulins, albumin, transthyretin
  116. 116What are the two forms of iron found in foods?Ferric Fe3+ and ferrous Fe2+
  117. 117List three substances which may inhibit iron absorption?Polyphenols such as tea and coffee; oxalic acid found in spinach, chard,
    berries, chocolate; phytates found in grains; EDTA preservative; phosvitin protein
    in egg yolks; nutrients such as calcium, zinc, manganese.
  118. 118Iron travels in the blood bound to what?Transferrin
  119. 119Iron is stored bound to what?Ferritin
  120. 120Name two ways manganese is transported through circulation?Bound to transferrin; free; bound to albumin or α-2 macroglobulin
  121. 121Iron competes for absorption with manganese. Why may this be the case?Use the same transporter DMT1
  122. 122Which two ways is molybdenum transported in circulation?Albumin and a-2 macroglobulin
  123. 123What are the two mechanisms of molybdenum absorption and why would one method be utilised over another?Concentration dependent passive diffusion with high intakes and carrier
    mediated sodium dependent active transport at low intakes
  124. 124What form of selenium is thought to be better absorbed?Selenomethionein
  125. 125Name two factors which increase absorption of selenium?Vitamin A, C, E and the presence of reduced glutathione in the intestinal
    lumen
  126. 126Name two ways selenium may be transported in circulation?Either in free form or bound to albumin
  127. 127By which mechanism is selenium taken into and out of circulation?Passive diffusion
  128. 128Are high or low concentrations of zinc absorbed?Low concentrations
  129. 129Name two substances which enhance zinc absorption?Citric acid, picolinic acid, amino acids such as histidine and cysteine;
    glutathione, tripeptides and low zinc status
  130. 130Name three substances which may inhibit zinc absorption?Fiber, phytates, oxalates, polyphenols and some nutrients with divalent
    bonds such as magnesium, iron and calcium
  131. 131Name four substances may zinc be bound to in the blood?Albumin, transferrin, α-2 macroglobulin, and immunoglobulin g (IgG)
  132. 132Name three other minerals are known to use the same transporter DMT1, as zinc?Iron, manganese, copper
  133. 133What substance is zinc incorporated into for storage inside cells?Metallothionein
  134. 134Boron is thought to move into and out of cells by which mechanism?Passive diffusion
  135. 135Where is boron found mainly in the body?Bones, teeth, nails, hair
  136. 136What is vanadium bound to for transport through circulation?Transferrin
  137. 137What is vanadium bound to for storage inside cells?Ferritin
  138. 138Vanadium mimics the action of which hormone?insulin
  139. 139. Which other nutrients use these same storage mechanisms?iron

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Revision Final Exam Sessions 1-4
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Eleni Cico
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