carbohydrates sbi4uo

							Carbohydrates
Discussion Questions:
(Groups of 2 – 5 minutes!!!)
   List some food items rich in carbohydrates.
   What is the difference between complex
    carbohydrates versus simple carbohydrates?
   Would you recommend a person who wants
    to lose weight to adopt a low-carb diet?
Canada’s Food Guide

   Carbohydrates make up the
    largest volume of our daily
    food
   Carbohydrates are found in:
    grain flour, cereals, pasta,
    potatoes and other
    vegetables, fruits, syrups,
    honey, candy, pop, juice,
    milk as well as in the pure
    crystalline form of our
    familiar table "sugar".
Functions of Carbohydrates

       Energy source
       Plays a vital part in the digestion,
        metabolism, and oxidation of protein and
        fat.
       Too much carbohydrate =
        Glycogen in liver OR
        Fat
Simple versus Complex Carbohydrates
   Simple Carbs:
       Quick source of energy (do not supply other nutrients or fiber)
       Quickly absorbed – rapid increase in blood sugar level followed by quick decline
       Small molecules (glucose, fructose, maltose, sucrose, lactose)
       Found in: fruit, fruit juice, table sugar, honey, soft drinks, and other sweets
   Complex Carbs:
       Supply energy and other nutrients and fiber
       Slowly digested – steady slow rise in blood sugar level
       Large molecules (starch and dietary fiber)
       Starch: breaks down into smaller carbs; supplies long, sustained energy to the
        body
           bread, cereal, potatoes, pasta, rice, and legumes (dried peas and beans)
       Dietary fiber:
           found in plant cells (non-digestible part of plants)
           tough and stringy
           it does not break down completely in the body
           Essential for regulating the body (digestion).
           bran, whole-grain foods, raw vegetables and fruit (especially the seeds and skins),
            legumes, nuts, seeds and popcorn
Some General Chemical Info

   Hydrophilic organic molecule
   General formula
       (CH2O)n , n = number of carbon atoms
       for glucose, n = 6, so formula is C6H12O6
   Names of carbohydrates
       word root sacchar- or the suffix -ose often used
           monosaccharide or glucose
Aldoses and Ketoses
   Aldoses contain the aldehyde group
   Ketoses contain the ketone group
Ring Formation
   In aqueous solution, the aldehyde and
    ketone groups react with hydroxyl (-OH)
    group belonging to the same molecule
Monosaccharides

    Simplest carbohydrates
    General formula is C6H12O6
        structural isomers

    Three major
     monosaccharides
        glucose, galactose and fructose
        mainly produced by digestion of
         complex carbohydrates
Sugar Derivatives
   The hydroxyl groups of a simple
    monosaccharide can be replaced by other
    groups
Alpha (a) and Beta (b) Links
   The hydroxyl group on the carbon that carries
    the aldehyde or ketone can rapidly change
    from one position to the other




                b                 a
Disaccharides

   Pairs of
    monosaccharides
   Three major
    disaccharides
       sucrose
           glucose + fructose
       lactose
           glucose + galactose
       maltose
           glucose + glucose
Dehydration Synthesis
of a Disaccharide




    Dehydration synthesis of two glucose molecules
     results in the formation of maltose
    The C-O-C bond formed is called a glycosidic
     bond
    Polysaccharides
   Starch, cellulose and glycogen
       long chains of glucose form these polysaccharides
   Starch produced by plants is digested by amylase
   Cellulose gives structure to plants, fiber to our
    diet
    Starch Hydrolysis




   The digestion of starch occurs by the hydrolysis
    of the glycosidic bond.
   Amylase is the enzyme.
   Maltose is the product.
Polysaccharides

   Glycogen is an energy storage
    polysaccharide produced by animals
   Liver cells synthesize glycogen after a meal
    to maintain blood glucose levels
    Carbohydrate Functions
   Source of energy
   Conjugated carbohydrates
       glycolipids
           external surface of cell membrane
       glycoproteins
           external surface of cell membrane
           mucus of respiratory and digestive tracts
       proteoglycans
           carbohydrate component dominant
           cell adhesion, gelatinous filler of tissues (eye) and lubricates
            joints
    Moieties of Macromolecules

   A moiety is a chemically different component of a
    conjugated macromolecule
       Glycolipid
       glycoprotein