Monosaccharides are multiples of CH₂O

glucose = aldose fructose = ketose

}structural isomers

Disaccharides are two monosaccharides with a glycosidic linkage.  For every glycosidic linkage subtract HOH from the CHOH complex.

example:  sucrose = fructose + glucose = C₁₂H₂₂O₁₁ (C₁₂H₂₄O₁₂ - H₂O)

The glycosidic linkage between alpha glucose and fructose is a 1st carbon to 2 carbon link.

Plants usually only transport sucrose. Why would they do that?

lactose = beta galactose + beta glucose; maltose (below, right) = 2 alpha glucoses in a 1-4 linkage

alpha glucose is used in disaccharides and storage polysaccharides (starch, glycogen--amylopectin)

beta glucose is used in structural polysaccharides (chitin, cellulose)

Polysaccharides include starch, glycogen, chitin, and cellulose. Starch is alpha glucoses in 1-4 linkages.  Glycogen is amylopectin; essentially starch with more branches of alpha glucolic strands extending from each other.

Cellulose is beta glucose in 1-4 linkages. Cellulose is grouped into approx. 80 chains to form the microfibrils in the cell wall of plants.  Microfibrils scrape the walls of the intestines, stimulating mucus production which "greases up" the tract for easy food passage.  "Fiber" is cellulose.

Pure chitin is leathery but when crusted with calcium carbonate (CaCO₃) it hardens.  Fungi use chitin for their cell walls.  The chitin monomer is glucose with NH-CO-CH₃ (amino-carbonyl-methyl) attached to the 2nd carbon.

Lipids have little or no affinity for HOH because they consist mostly of hydrophobic hydrocarbons.

1. glycerol = alcohol + 3 carbons with OH attached to them
   fatty acid = 16-18 carbon skeleton with a "head" consisting of a carboxyl (COOH) group
   1. thus 3 fatty acids connect with a glycerol (3 OH section) to form fat: triglyceride.
   2. the fatty acids in a fat can be identical or no.
2. eg. wax, steroids, fats/oils, phospholipids
   1. Fats and Oils.  If unused in 6 weeks, are destroyed by the body.
      1. saturated fat = no double bonds or triple bonds; saturated with H
         • solidify at room temperature
         • are from animals
         • commonly called "fat"
      2. monounsaturated fat = 1 double bond; loses a H to double bond with another C
         • C=C formed due to removal of H atoms
         • is a liquid at room temperature
         • unsat. fats are from plants
      3. polyunsaturated fat = 2+ double bonds or triple bond; less H present than monounsaturated fat
      4. Why is unsaturated fats healthier?
         wherever there is a C=C ther is a kink in the C skeleton thus preventing the molecules from packing tightly together to solidify @ room temperature and clog passages
      5. "Hydrogenated oil" refers to unsaturated fat made synthetically into saturated fat by adding H
         eg.  peanut butter and margarine
      6. Why are fats important?
         one gram of fat stores twice the amount of energy as one gram of a polysaccharide
      7. Why plants use starch...
         Since they are immobile they can function with bulky energy storage.  Animals are mobile so the need a more compact source of long term energy (remember how glycogen has more "twists and turns" than starch).
      8. Adipose Cells are where animals store fat (long term food reserves).  They shink and expand with the amount of fat present because fat is continually withdrawn and deposited, and cushion the kidneys and insulate the body in the subcutaneous layer of the skin.
   2. Phospholipids consist of a hydrophobic tail and a hydrophilic head.  Thus they are amphipathic (hydrophilic and hydrophobic). When added to HOH they assemble into aggregates (clusters) that shield their H-phobic portions from the water.  They are semi-hydrophilic because of glycerol head.
      1. eg. micelle is like a phospholipid droplet
          O = the head;  ~~ = the tail
      2. At the surface of a cell, they form a phospholipid bilayer, forming a boundary between the cell and its environment
         
   3. Steroids are lipids consisting of 4 C skeletons in interconnecting rings.  Cholesterol is a common component in animal cell membranes.  Most other steroids are synthesized from cholesterol.