1. 4 functions of carbohydrates
    • 1. provide energy through oxidation
    • 2. supply carbon for synthesis of cellular compounds
    • 3. serve as a stored form of chemical energy
    • 4.form a part of the structural elements of some cells and tissues
  2. definitions of carbohydrates
    polyhydroxyl aldehydes or ketones, or substances that yield such compounds on hydrolysis
  3. General formula for carbohydrates
  4. Functional groups of carbohydrates
    C=O and OH
  5. Carbohydrates are classified based on:
    • size of base carbon chain
    • number of sugar units
    • location of C=O
    • stereochemisty
  6. monosaccharides
    single sugar units
  7. disaccharides
    two sugar units
  8. oligosaccharides
    2 to 10 sugar units
  9. polysaccharides
    more than 10 units
  10. aldose
    has an aldehyde functional group
  11. ketose
    has a ketone functional group
  12. 3 carbon chain
  13. 4 carbon chain
  14. 5 carbon chain
  15. 6 carbon chain
  16. sterochemistry
    study of the spatial arrangment of molecules
  17. sterisomers
    • the same order and types of bonds
    • different spatial arrangement
    • different properties
    • Many biologically important chemicals, like sugar, exist as steroisomers. Your body can tell the difference
  18. Enantiomers
    • designed by D- or L-0 at the start of the name
    • they are mirror images that can't be overlapped
  19. Chiral center
    Asymmetric carbon:
    • 4 different groups are attached to it
    • you must have at least one asymmetric C to have a stereoisomer
  20. Chiral carbons:
    • Note: molecules of all enzymes are chiral. Thus enzymes are very specific
    • Its molecules are like left hands rummaging through a box of right handed gloves- nothing fits
  21. optical activity
    ability to rotate plane polarized light
  22. dextrorotatory
    • rotate to right
    • use + symbol
    • usually D isomers
  23. leveorotatory
    • rotate to left
    • use - symbol
    • usu. L isomers
  24. Properties of sugars
    • colorless, crystallin solids
    • they can form H bonds w/ H2O
    • solubility is extensive in water
    • soluble to a small extent in ethanol
    • any other solvent not soluble in
  25. Fischer Projection
    • These are 2 dimensional structures
    • The chiral carbon is represented by the intersection of 2 lines
    • In carbohydrates, the carbonyl group is placed at or near the top depending upon whether the sugar is an aldose or ketose
    • D- and L- designations are used to indicated the position of teh OH group on the chiral carbon farthest from the carbonyl group
  26. Maximum number of possible steroisomers
    • 2n
    • n= # of chiral carbon centers

  27. Amino sugars
    • contain an amino group in place of an -OH group
    • only 3 amino sugars are common in nature
    • they are D- glucosamine, D- mannosamine, D- galactosamine
  28. Glucose
    • an aldohexose sugar
    • common names include dextrose
    • most important sugar in our diet
    • most abundant organic compound found in nature
    • level in blood can be as high as 10%
  29. Galactose
    • seldom encountered as a free monosaccharide
    • in body, galactose is synthesized from glucose in mammory glands for use in lactose (milk sugar)
  30. Fructose
    • ketohexose
    • sweetest of all sugars
    • also know as levulose (+) and fruit sugar
  31. ribose
    • a component of a variety of complex molecules including RNA and energy rich compounds such as ATP
    • compounds 2-deoxy-D-ribose is also important in nucleic acid chemistry
    • this monosaccharide is a component of DNA
    • the term deoxy means minus as oxygen 2-deoxy-lacks an oxygen on carbon 2
  32. intramolecular cyclization
    • sugars also form rings. from many sugars, its the most common form.
    • hemiacetal- form from alcohol & aldehydes
    • hemiketal- form from alcohol & ketone
  33. anomer
    • the -OH group that froms can be above or below the ring resulting in two forms
    • we use alpha and beta to identify
  34. mutarotation
    the alpha and beta forms are in equilibrium so one or can convert to the other
  35. Reducing sugars
    • aldehyde sugars are readily oxidized and will react with Benedict's reagent
    • good test for presense of glucose in urine
  36. Reducing sugars
    aldehyde sugars are readily oxidized and will react with Benedict's reagent
  37. Oxidation of Monosaccharides
    D-glucose--->D-gluconic acid
  38. Reduction of monosaccharides
    • reduction--->polyhydroxy alcohols
    • D-glucose--->D-glucitol (sorbitol)
  39. Sorbitol
    • properties similar to trihydroxy alcohol glycerol.
    • moisturizing agent in foods and cosmetics
  40. hydrolysis fo dissaccharides:
    • sucrose+water-->D-glucose+D-fructose
    • maltose+water--> D-glucose+D-glucose
    • lactose+water-->D-glucose+D-galactose
  41. Glycosidic bonds
    • type is base on the position of the C-1 OH
    • alpha glycosidic bond- linkage b/w a C-1 alpha OH and a C-4 OH
    • Beta glycosidic bond- linkage b/w a C-1 beta OH and a C-4 OH
  42. General format for glycosidic bond
    • Gen. formal used to describe bond
    • OH type (carbon# of 1st sugar-->carbon# of 2nd sugar)
    • for disaccharides- the sugar is either alpha or beta based on form of hte remaining C-1 OH
  43. Beta maltose
    named because:
    • not common in nature except in germinating grains
    • called beta maltose b/c unreacted C-1 on beta-D-glucose is in the beta postion
    • uses: ingredient in infant formulas, production of beer, flavoring
  44. sucrose
    • table sugar
    • disaccharide of alpha glucose and beta fructose
  45. cellobiose
    • composed of two molecules of D-glucose
    • the difference in the linkage results in cellobiose being unusable (beta 1-4 linkage)
  46. Lactose
    milk sugar- dimer of beta-D-galactose and either the alpha or beta-D-glucose
  47. polysaccharides
    • no fixed size
    • used to store excess sugar
    • can be used by plants to make cell walls and other sturctures
Card Set
Chapter 17: carbohydrates