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2012-09-08 22:52:36
Carbohydrates biochemistry NSU

Introduction to Carbohydrates
Show Answers:

  1. What are carbohydrates? Aldoses? Ketoses?
    • Carbohydrates are polyhydroxy aldehydes, polyhydroxy ketones or and compound that when hydrolyzed yield these 2 products. 
    • Aldoses are monosaccharides that have an aldehyde group
    • Ketoses are monosaccharides that have a ketone group
  2. What is the most important monosaccharide, and what polysaccharides are made up of this saccharide?
    • Glucose is the most important monosaccharide.
    • Polysaccharides made up of glucose are starch, cellulose and glycogen.
  3. Pyran and furan are organic compounds for which what sugar structures are named? How many atoms per ring?
    • Pyran is a 6 membered ring (Pyranose)
    • Furan is a 5 membered ring (Furanose)
  4. What is mutarotation, where does it take place?
    Mutarotation involves changes in configuration at the anomeric carbon by ring opening and closing
  5. What are two conformations of 6 membered rings?
    Boat and chair confirmation. (Chair is more stable)
  6. How are sugar acids named?
    • If they contain a terminal aldehyde that is oxidized to an acid it is known as an -aldonic acid. 
    • If they contain a terminal hydroxyl group being oxidized to an acid then it's a -uronic acid.
    • If the both are oxidized: -aldaric acid
  7. Name and describe the two commonly found modifications of sugars.
    Glucosamine and galactosamine are sugars that instead of containing 1 hydroxyl group it contains an amine group.
  8. What is glycoside and aglycone?
    Glycoside: A compound formed when the anomeric -OH reacts with another hydroxide compound. The sugar providing the anomeric C is the named sugar. The other compound is the aglycone.
  9. Which of the three most important polysaccharides have alpha linked sugars? beta linked? What is the importance of this?
    • "Starch": Amylopectin (a branched chain of α-linked maltose) 
    • Amylose (an unbranched α-linked chain of maltose). Cellulose: A β-linked chain of Glu.

    Possibly because β-linked things are hard to digest like lactose (Galac β Glu). in this case cellulose is impossible to digest.
  10. Name 3 imporatnt disaccharides and tell which have alpha and beta linked sugars
    • maltose: glucose linked
    • lactose: beta linked
    • sucrose: alpha linked
  11. Tell what glycosaminoglycans are and name 2
    GAGS are unbranched polysaccharides made up of repeating disaccharides of an amino sugar and uronic acid.

    2 glycosminoglycans (GAG) are: hyalutonic acid and heparin
  12. In the A, B, O blood group substances where is the difference in the structures of the oligosaccharides located? How may sugars are different?
    The particular ABO type is defined by the absence or presence of Galactose or N-acetyl galactosamine on a surface sphingolipid