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Flashcards

Carbohydrates

Adrianna Bialecka Med Chem and Chem Bio University English 90 cards

Carbohydrates

Cards in this deck (90)

  1. 1Why are carbohydrates relevant?-The majority of (dry) biomass on the planet
    -They are involved in basic biology, e.g., plant structure, energy storage (natural CO2 capture) [starch, cellulose]
    -Complex biology, e.g., what is the molecular basis for blood groups (O, A, B, AB) how viruses invade your cells, a way to make vaccines, anti-clotting drugs (heparin), medicines (AZT), etc
  2. 2What does it mean that protein are glycosylated?-Many proteins have further groups added, e.g. carbohydrates
    -Many are heavily glycosylated
  3. 3What do many cells have on the outer surface?have a glycocalyx on the outer surfaceWhat do many cells have on the outer surface?
  4. 4What carbohydrates are crucial components of RNA and DNA?Ribose and deoxyribose in nucleotidesWhat carbohydrates are crucial components of RNA and DNA?
  5. 5What are carbohydrates?They are polyhydroxylated aldehydes and ketones
  6. 6What are Monosaccharides?-Simple sugars that can't be converted into simpler sugars by hydrolysis e.g. glucose, fructose
  7. 7What are Oligosaccharides?are made of two or more monosaccharides joined together, e.g., sucrose is a disaccharide made from glucose and fructose
  8. 8What are polysaccharides?polymers of many monosaccharides joined together, e.g. cellulose is an important polymer of glucose
  9. 9What are the two classes of monosaccharides?Aldoses (aldehyde) and Ketoses (ketone)
    -ose indicates it is a carbohydrate
    -The number of carbons present is indicated by the usual prefixes (tri, tetra, pent, hex etc). Glucose is an aldohexose, fructose is a ketopentose
  10. 10Examples of monosaccharidesExamples of monosaccharides
  11. 11How do you draw carbohydrates?How do you draw carbohydrates?
  12. 12What is the chemistry of monosaccharide structures- aldoses?What is the chemistry of monosaccharide structures- aldoses?
  13. 13What is the chemistry of monosaccharide structures- ketoses?What is the chemistry of monosaccharide structures- ketoses?
  14. 14What are the cyclic structures of monosaccharides?What are the cyclic structures of monosaccharides?
  15. 15If the cyclic form is a 5-membered ring, then the sugar is a ...?furanose
  16. 16If the cyclic form is a 6-membered ring, then the sugar is a ...?pyranose
  17. 17When is it an alpha anomer and when is it beta?When is it an alpha anomer and when is it beta?
  18. 18How are the two different anomer forms in equilibria?How are the two different anomer forms in equilibria?
  19. 19What is the chemistry of disaccharides?What is the chemistry of disaccharides?
  20. 20What is the glycosylation reaction?What is the glycosylation reaction?
  21. 21What is the structure of Maltose?What is the structure of Maltose?
  22. 22What is the structure of Lactose?What is the structure of Lactose?
  23. 23What is the structure of Sucrose?What is the structure of Sucrose?
  24. 24What are the different ways of drawing sugars?What are the different ways of drawing sugars?
  25. 25What is the structure of glycogen?What is the structure of glycogen?
  26. 26What is the structure of Starch?What is the structure of Starch?
  27. 27What is the structure of Cellulose?What is the structure of Cellulose?
  28. 28What is the mechanism of Acid-catalysed Acetal formation?What is the mechanism of Acid-catalysed Acetal formation?
  29. 29What is glucose?-Glucose is biosynthesised in photosynthesis
    -It is transformed by enzymes into starch and cellulose
    -It is generally found as D-glucose (determined by configuration in red)
    -It is sometimes abbreviated as 'Glc'
    -In Beta-D-glucose all of the substituents on the ring are equatorial    What is glucose?
  30. 30What are the fischer projections of other monosaccharides?What are the fischer projections of other monosaccharides?
  31. 31What are the most common monosaccharides in humans (fischer projections)?What are the most common monosaccharides in humans (fischer projections)?
  32. 32What are the most common monosaccharides in humans (cyclic)?-Mannose and galactose are epimers of glucose
    -Amide, carboxylic acid and deoxy variants are also very important
    -Furanose forms are typically represented in Haworth projections
    -Pyranose forms are typically shown as chairs    What are the most common monosaccharides in humans (cyclic)?
  33. 33How to draw sugars in chair conformation?How to draw sugars in chair conformation?
  34. 34How are cyclohexanes drawn in chair conformation?How are cyclohexanes drawn in chair conformation?
  35. 35How are cyclohexanes drawn in boat conformations?How are cyclohexanes drawn in boat conformations?
  36. 36What is cyclohexanes conformational flexibility?What is cyclohexanes conformational flexibility?
  37. 37How do cyclohexanes ring flip?How do cyclohexanes ring flip?
  38. 38What is the conformation that is preferred with monosubstituted cyclohexanes?What is the conformation that is preferred with monosubstituted cyclohexanes?
  39. 39What is the conformation that is preferred with polysubstituted cyclohexanes?What is the conformation that is preferred with polysubstituted cyclohexanes?
  40. 40Which chair form dominates in glucose?Which chair form dominates in glucose?
  41. 41Which form of glucose, beta or alpha, dominates?Which form of glucose, beta or alpha, dominates?
  42. 42How to name simple sugars?How to name simple sugars?
  43. 43What are the different representation of sugars?What are the different representation of sugars?
  44. 44What is the test used to identify reducing sugars?What is the test used to identify reducing sugars?
  45. 45What oxidation reaction do monosaccharides have?What oxidation reaction do monosaccharides have?
  46. 46What reduction reaction do monosaccharides have?What reduction reaction do monosaccharides have?
  47. 47What are some reactions of monosaccharides?What are some reactions of monosaccharides?
  48. 48What are some abbreviations for protecting groups of sugars?What are some abbreviations for protecting groups of sugars?
  49. 49Fischer glycosylation reaction at anomeric centre?Fischer glycosylation reaction at anomeric centre?
  50. 50How are disaccharide made?How are disaccharide made?
  51. 51What are some disaccharide examples?What are some disaccharide examples?
  52. 52How are disaccharides named?How are disaccharides named?
  53. 53Naming of lactose and sucroseNaming of lactose and sucrose
  54. 54What is the strategy in identifying anomeric center in different representations of sugars?What is the strategy in identifying anomeric center in different representations of sugars?
  55. 55What is the most stable representation of sugars?What is the most stable representation of sugars?
  56. 56How are cellulose named?How are cellulose named?
  57. 57How is starch named?How is starch named?
  58. 58Why is it difficult to isolate oligosaccharides?Why is it difficult to isolate oligosaccharides?
  59. 59What challenges are involved in chemical oligosaccharides synthesis and how they are overcome?What challenges are involved in chemical oligosaccharides synthesis and how they are overcome?
  60. 60What are is the glycosylation mechanism 1: SN1-like reactionsWhat are is the glycosylation mechanism 1: SN1-like reactions
  61. 61What are the three popular methods of glycosylation mechanism?What are the three popular methods of glycosylation mechanism?
  62. 62Full reaction mechanism for the three popular methods?Full reaction mechanism for the three popular methods?
  63. 63How is neighbouring group invovled in stereochemistry of glycosylation?How is neighbouring group invovled in stereochemistry of glycosylation?
  64. 64How are disaccharides chemically synthesised?How are disaccharides chemically synthesised?
  65. 65How are building blocks synthesised?How are building blocks synthesised?
  66. 66What is the strategy used in oligosaccharide synthesis?-Generally, the glycosyl acceptor is protected such that only a single hydroxy group is free
    -To enable oligosaccharide synthesis we use temporary protecting groups and persistent protecting groups
  67. 67What are temporary protecting groups?can be removed selectively to free a hydroxy group for a subsequent glycosylation (leaving other protecting groups in place
    -Examples include silyl ethers -OSiR3 (Which can be cleaved with fluoride)
  68. 68What are persistent protecting groups?They are only removed at the end of the synthesis. The most common is a benzyl ether -OBn (-OCh2Ph, which can be removed by hydrogenation)
  69. 69Why are not all acetals equal?Why are not all acetals equal?
  70. 70How are Anomeric Acetal Hydrolysed?How are Anomeric Acetal Hydrolysed?
  71. 71How are Benzylidene Acetals hydrolysed?How are Benzylidene Acetals hydrolysed?
  72. 72How are Isopropylidene acetals used as protecting groups?How are Isopropylidene acetals used as protecting groups?
  73. 73How are polysaccharides hydrolysed?How are polysaccharides hydrolysed?
  74. 74How do glycosidases work?How do glycosidases work?
  75. 75Reaction mechanism of inverting glycosidases explainedReaction mechanism of inverting glycosidases explained
  76. 76What happens after glycosidases are inverted?What happens after glycosidases are inverted?
  77. 77What is the key transition state of inverting glycosidases?What is the key transition state of inverting glycosidases?
  78. 78What is the reaction mechanism explaining retaining glycosidases first step?What is the reaction mechanism explaining retaining glycosidases first step?
  79. 79What is the reaction mechanism explaining retaining glycosidases second step?What is the reaction mechanism explaining retaining glycosidases second step?
  80. 80What are the key transition states for both steps of retaining glycosidases?What are the key transition states for both steps of retaining glycosidases?
  81. 81How are alpha-glucosidases inhibitors used in people suffering from diabetes?-alpha-glucosidases = Catalyse the hydrolysis of starch oligosaccharides to glucose
    -High glucosidase activity results in high blood glucose levels
    Treatment:
    Glucosidase inhibitors e.g. Miglitol    How are alpha-glucosidases inhibitors used in people suffering from diabetes?
  82. 82What is the mechanism of action of Miglitol?What is the mechanism of action of Miglitol?
  83. 83What are some examples of other digestive alpha-glucosidase inhibitors?What are some examples of other digestive alpha-glucosidase inhibitors?
  84. 84What are glycosyl transferases?Enzymes that catalyse the formation of glycosidic linkages. They are:
    ->Regiospecific (without requiring protecting groups)
    ->Stereospecific- generate either alpha or beta-configured products with high specificity
    ->Substrate specific- work on a specific substrate combination
    -The enzyme binds the substrates and positions them at the active site, enabling it to achieve high specificities
    ->One glycosyl acceptor alcohol is positioned to be the nucleophile
    ->The glycosyl donor is positioned to be attacked from a specific trajectory, thereby giving stereocontrol
    ->The binding sites don't bind well to "wrong" substrates, thus achieving substrate specificity
  85. 85What is an example of a typical glycosyl donor?What is an example of a typical glycosyl donor?
  86. 86How do inverting glycosyl transferases work?How do inverting glycosyl transferases work?
  87. 87How do retaining glycosyl transferases work?How do retaining glycosyl transferases work?
  88. 88What are the pros of using glycosyl transferases for synthesis?-Fast rates
    -Excellent substrate specificity
    -Regiospecificity -no protecting groups needed
    -Stereo specificity
  89. 89What are the cons of using glycosyl transferases for synthesis?-Specificity can be a problem if an enzyme isn't available for the linkage you want to make
    -The cost of the glycosyl donors and enzymes can be high (but a greater range are becoming more affordable)
    -Enzymes can be used to generate donors
  90. 90Structure and biosynthesis of glycoconjugates?Structure and biosynthesis of glycoconjugates?

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University Med Chem and Chem Bio Flashcards on Carbohydrates, created by Adrianna Bialecka on 26/02/2025.
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