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2009-12-05 12:52:35
chemistry carbohydrates

carbs for chemistry
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  1. isomers
    • Both structures represent molecules having the formula C4H10.
    • However, the arrangements of the atoms are different. These compounds are related as isomers (two compounds of the same formula, but different arrangement of atoms)
  2. chiral
    When a central carbon atom is bonded to 4 different groups, the mirror image is not identical to the original.
  3. Biological Function of Carbohydrates
    • • Immediate energy source for cell metabolism(glucose)
    • • Nutritional sources of energy (glucose, fructose, maltose, lactose)
    • • Short term storage of energy (starch, glycogen)
    • • Structural component in plant cell walls (cellulose)
    • • Markers on cell walls to identify cell type (e.g. blood type)
  4. Carbohydrates
    • • Carbohydrates are composed of C H and O.
    • • The simple carbohydrates have the empirical formula CH2O – "hydrate" of carbon
    • • All carbohydrates contain the "carbonyl group" ( C=O ) – either aldehyde or ketone
    • • All carbohydrates contain several –OH groups (hydroxy groups).
  5. General Types of Carbohydrates
    • • Monosaccharides – the simple sugars – examples: glucose, fructose
    • • Disaccharides – two monosaccharides bonded together – examples: sucrose, lactose
    • • Polysaccharides- many glucose units linked together – examples: starch, cellulose
  6. aldoses
    •Aldoses are monosacchrides with an aldehyde group and many hydroxyl (-OH) groups.
  7. ketose
    • Ketoses are monosacchrides with a ketone group and many hydroxyl (-OH) groups
    • c=o
  8. D and L Notation
    • •D,L tells which of the two chiral isomers we are referring to.
    • •If the –OH group on the next to the bottom carbon atom points to the right , the isomer is a D-isomer; if it points left, the isomer is L.The D form is usually the isomer found in nature.
  9. Monosaccharides
    • • Monosaccharides are the simplest carbohydrates
    • – cannot be broken down into simpler carbohydrates
    • • They all contain several OH groups (hydroxy) and 1carbonyl group (C=O)
    • • They are chiral molecules (they are not identical to their mirror images)
    • • They differ in the arrangement of the groups around the chiral carbons.
  10. Fischer Projections
    • • A method is needed to unambiguously designate the spatial arrangement of atoms when drawing a structure.
    • • A convention was developed by Emil Fischer (1852-1919) to show the exact arrangement of the atoms around a chiral carbon.
  11. •Monosaccharides are classified:
    • •According to # of carbons,
    • •Glucose is a hexose
    • •(a five carbon sugar is called a pentose)
    • •According to the nature of the carbonyl
    • •Glucose is an aldose •(sugars that have a ketone are called ketoses) •The complete classification of glucose is aldohexose
  12. Glucose
    • •Glucose is a monosaccharide (can't be broken into simpler sugars)
    • •Glucose is an aldose (contains an aldehyde group)
    • •Glucose is a aldohexose (an aldehyde group with a total of 6 carbon atoms)
    • •Glucose = "blood sugar"
  13. Galactose
    • •Galactose is a monosaccharide (can't be broken into simpler sugars)
    • •Galactose is a aldose (contains an aldehyde group)
    • •Galactose is a aldohexose (contains an aldehyde and a total of 6 carbon atoms)
    • •Galactose is a component of milk sugar ( lactose, a disaccharide)
  14. RIBOSE
    • •Ribose is a monosaccharide (can't be broken down into simple sugars)
    • •Ribose is an aldose (contains an aldehyde group)
    • •Ribose is a aldopentose (contains an aldehyde and a total of 5 carbon atoms)
    • •Fructose is a monosaccharide (can't be broken into simpler sugars)
    • •Fructose is a ketose (contains a ketone group)
    • •Fructose is a ketohexose (contains a ketone and a total of 6 carbon atoms)
    • •Fructose is the sweetest of sugars
  16. Reactions of Monosaccharides
    (Reducing Sugars)
    Certain sugars have the ability to convert Cu+2 solutions (Benedict’s solution) to Cu2O, which is a red solid. Since the Cu+2 is reduced to Cu+1, these sugars are called reducing sugars
  17. Cyclic Structures of Monosaccharides
    • •Monosaccharides with 5-6 carbon atoms form cyclic structures
    • •The hydroxyl group on C-5 reacts with the aldehyde group or ketone group
  18. Haworth Structure for D-Isomers
    The cyclic structure of a D-isomer has the final CH2OH group located above the ring.
  19. Disaccharides

    Disaccharides can be broken down by acidic water (hydrolyzed) to give monosaccharides
    • Maltose (malt sugar)  glucose + glucose
    • Lactose (milk sugar)  glucose + galactose
    • Sucrose (table sugar) glucose + fructose
  20. Carbohydrates as Cell Markers
    • • Modified carbohydrates are attached to cell membranes (cell walls)
    • • They serve as ‘markers’ to identify the cell type
    • • In this way, they tell the immune system that the cell belongs to the organism and is not a foreign organism (bacteria or parasite)
    • • A common example of this is in the determination of blood types
  21. Polysaccharides
    • • Starch-storage form of glucose in plants – Amylose (20%): 200-4000 a glucose monomers attached a-1,4 in a continuous chain (polymer)
    • • chains tend to coil so as to pack more tightly – Amylopectin (80%): Similar to amylose, but contains occasional branches on the main chain.
    • • chains tend to coil like amylose
  22. Polysaccharides (cont)
    • • Glycogen("animal starch"- storage form of glucose in animals – mainly in liver and muscle – similar to amylopectin, but more highly branched
    • • Cellulose: major structural material in plants – gives strength to cell walls
    • – long chain of mainly unbranched glucose units
    • – however, glucose units are linked via 1,4 b linkages.
    • – chains tend to be aligned and held together by H bonds.
  23. Summary-Functions of Carbohydrates
    • • Carbohydrates are a used to provide energy for cellular functions (ex-glucose)
    • • Carbohydrates are used to provide (relatively short term) storage of energy (starch)
    • • Carbohydrates are an important component in cell walls of plants (cellulose)
    • • Carbohydrate derivatives are used as cell markers (antigens for blood type)
  24. Key Features of Organic Chemistry
    • •Carbon forms 4 bonds when forming molecules (exception: carbon monoxide)
    • •Compounds containing only carbon and hydrogen are called hydrocarbons.
    • •Atoms bonded together by single bonds are can rotate about the bond.
    • •Atoms bonded together by double bonds cannot rotate about the bond.
    • •Compounds having the same molecular formula but different arrangement of atoms are called isomers
  25. enantiomers
    two mirror images