Biochem 2

Card Set Information

Biochem 2
2011-12-07 23:11:21
Biochem Carbohydrates Carbs

Biochem 2- Carbohydrates
Show Answers:

  1. How are carbohydrates produced?
    Produced from CO2 and H2O via photosynthesis in plants
  2. Whare are some functions of carbohydrates?
    • Energy source and energy storage
    • Structural component of cell walls and exoskeleton
    • Informational molecules in cell-cell signaling
  3. What is formed when carbohydrates are covalently linked with proteins?
    Glycoproteins and proteglycans
  4. How are glycoproteins and proteoglycans formed?
    Formed when carbohydrates are covalently linked with proteins
  5. What is the simplest carbohydrate?
  6. What is an enantiomer?
    When two molecules are mirror images of eachother
  7. What are epimers?
    two sugars that differ only in the configuration around one carbon atom
  8. What is produced after the cyclization of monosaccharides?
    Gives rise to structures that are hemiacetals for aldoses and hemiketals for ketoses
  9. What compounds readily undergo imtramolecular cyclization?
    Pentoses and hexoses
  10. What changes occur in the cyclization of monosaccharides?
    • The former carbonyl carbon becomes a new chiral center, called the anomeric carbon-giving rise to an anomeric pair
    • The former carbonyl oxygen becomes a hydroxyl group; the position of this group determines if the anomber is alpha or beta
  11. What is an alpha anomer?
    If the hydroxyl group is on the opposite side (trans) of the ring as the CH2OH moiety
  12. What is a beta anomer?
    If the hydroxyl group is on the same side (cis) of the ring as the CH2OH moiety
  13. What is mutarotation?
    The conversion between alpha and beta anomers
  14. What is a six-membered oxygen-containing ring known as?
  15. What is a five-membered oxygen-containing ring known as?
  16. How are pyranoses and furanoses usually frawn?
    The anomeric carbon is usually drawn on the right side
  17. What are the three structural representaions of monosaccharides?
    • Fischer projection
    • Haworth Projection
    • Chair Confirmation
  18. What is produced when monosaccharides oxidize?
    A carboxylic acid
  19. What do monosaccharides need to undergo oxidation?
    Fehlings solution
  20. How are disaccharides formed?
    By condensation reaction between two alcohol groups
  21. What are some chemial modifications of monosaccharides?
    • Phosphorylation
    • Amidation
    • Acetylation
    • Oxidation
  22. How are natural carbohydrates usually found?
    Usually found as polymers
  23. What are the 2 types of polysaccharides?
    • Homopolysaccharides
    • Heteropolysaccharides
  24. What are homopolysaccharides?
    A polymer with the same monosaccharide repeated many times along the chain
  25. What is a heteropolysaccharide?
    A polysaccharide chain with many different types of monosaccharides
  26. What is the main storage homo-polysaccharide in plants?
  27. What is starch?
    A mixture of two homo-polysaccharides of glucose
  28. What is amylose?
    An unbranched polyer of (alpha1-4 linked residues)
  29. What is amylopectin?
    A branched polymer (alpha1-4) linked resudes BUT the branch-points with (alpha1-6) linkers occur every 24-30 residues
  30. What is the molecular weight of amylopectin?
    up to 200 million
  31. What is glycogen?
    Main carbohydrate storage system in animal cells
  32. Where is Glycogen often stored?
    Liver is primary storage location (7% by weight)
  33. What is cellulose?
    A fibrous, water insoluble polymer of unbranched homopolysaccharide of glucose found in the cell wall of plants
  34. What is cotton?
    a neearly pure fibrous cellulose
  35. What is the most abundant polysaccharide in nature?
  36. Why is cellulose a difficult substrate to act on?
    Its fibrous structure and water-insolubility
  37. How can fungi, bacteria and protazoa use wood as a source of glucose?
    Fungi, bacteria, and protazoa secrete cellulase, which breaks down cellulose
  38. Why can most animals not used cellulose as a fuel source?
    They lack the enzyme to hydrolyze linkages