Chapter 12
This presentation is the property of its rightful owner.
Sponsored Links
1 / 38

Chapter 12 Carbohydrates PowerPoint PPT Presentation


  • 53 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 12 Carbohydrates. Carbohydrates. Carbohydrate: a polyhydroxyaldehyde or polyhydroxyketone , or a substance that gives these compounds on hydrolysis. Monosaccharide : a carbohydrate that cannot be hydrolyzed to a simpler carbohydrate.

Download Presentation

Chapter 12 Carbohydrates

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 12 carbohydrates

Chapter 12

Carbohydrates


Carbohydrates

Carbohydrates

  • Carbohydrate: a polyhydroxyaldehyde or polyhydroxyketone, or a substance that gives these compounds on hydrolysis.

  • Monosaccharide:a carbohydrate that cannot be hydrolyzed to a simpler carbohydrate.

    • Monosaccharides have the general formula CnH2nOn, where n varies from 3 to 8.

    • Aldose: a monosaccharide containing an aldehyde group.

    • Ketose: a monosaccharide containing a ketone group.


Monosaccharides

Monosaccharides

  • Monosaccharides are classified by their number of carbon atoms.


Chapter 12 carbohydrates

Example: aldo (from aldehyde)

pent (from 5 carbons)

ose (family name)

ALDOPENTOSE


Chapter 12 carbohydrates

  • Example

    • keto (from ketone)

    • hex (from 6 carbons)

    • ose (family name)

KETOHEXOSE


Chirality

CHIRALITY


Chapter 12 carbohydrates

  • Chiral- compounds or objects that can not

    be superimposed on their mirror image.

    Object is different from its mirror image

  • Achiral (nonchiral)- compounds or objects that can be superimposed on their mirror image.

    Object is the same as its mirror image


Chiral molecules

CHIRAL MOLECULES


Chapter 12 carbohydrates

  • A chiral carbon is one that has four different groups attached to it.

  • A carbon with four different groups bonded to it is called a stereocenter.


Examples

EXAMPLES


Chapter 12 carbohydrates

  • Enantiomers- Isomers where the

    • molecule and its mirror image are different.

    • They always occur in pairs


Two stereocenters

Two Stereocenters

  • For a molecule with nstereocenters, the maximum number of possible stereoisomers is 2n.

    • We have already verified that, for a molecule with one stereocenter, 21 = 2 stereoisomers (one pair of enantiomers) are possible.

    • For a molecule with two stereocenters, a maximum of 22 = 4 stereoisomers (two pair of enantiomers) are possible.

    • For a molecule with three stereocenters, a maximum of 23 = 8 stereoisomers (four pairs of enantiomers) are possible.


Stereoisomers

Stereoisomers

  • example: Mark all stereocenters in each molecule and tell how many stereoisomers are possible for each.


Chirality in biomolecules

Chirality in Biomolecules

  • how an enzyme distinguishes between a molecule and its enantiomer.


Chapter 12 carbohydrates

  • The S enantiomer of naproxen is the active pain reliever, but its Renantiomer is a liver toxin!


Chapter 12 carbohydrates

Carvone

*

*


Chapter 12 carbohydrates

Thalidomide

*

*


Chapter 12 carbohydrates

Fructose


Monosaccharides1

Monosaccharides

  • Fischer projection:a two dimensional representation for showing the configuration of tetrahedral stereocenters.

    • Horizontal lines represent bonds projecting forward from the stereocenter.

    • Vertical lines represent bonds projecting to the rear.

    • Only the stereocenter is in the plane.


Fischer projections

Fischer Projections


Chapter 12 carbohydrates

  • D-Glucose forms these cyclic hemiacetals.


Chapter 12 carbohydrates

Haworth Projections

Monosaccharides with 5 or more carbons exist as rings

Haworth projection

ALDOSE


Chapter 12 carbohydrates

Haworth projection

Fischer projection

KETOSE


Important monosaccharides

Important Monosaccharides

  • Glucose

  • Aldohexose

  • Most nutritionally important monosaccharide

  • Sometimes called dextrose or blood sugar


Galactose

Galactose

  • A component of lactose (milk sugar)

  • Aldohexose


Fructose

Fructose

  • Ketohexose

  • Sometimes called fruit sugar

  • Component of sucrose


Disaccharides

Disaccharides

  • Two monosaccharide units linked together

Glycosidic

Linkage (1→4)

Glucose

Glucose

Maltose


Important disaccharides

Important Disaccharides

  • Maltose

  • Glucose + Glucose

  • Malt sugar

  • Found in fermenting grains


Lactose

Lactose

  • Glucose + Galactose

  • Milk sugar


Lactose intolerance

Lactose Intolerance

  • Enzyme Lactase low or absent

  • Lactose fermented in the intestine

  • Nausea, cramps, bloating, gas, and diarrhea


Sucrose

Sucrose

  • Fructose + Glucose (1→2)

  • Found in many plants (especially sugar cane, sugar beets)

  • Table sugar

glucose

fructose


Polysaccharides

Polysaccharides

  • More than 10 monosaccharides linked together

Glycosidic

linkage


Chapter 12 carbohydrates

  • Starch

  • Polymer of 30 to 1000 glucose units

  • Storage form of glucose in plants

  • Cereal grains (wheat, rice, corn, oats, barley) as well as tubers such as potatoes are rich in starch


Glycogen

Glycogen

  • Polymer of glucose units

  • Storage form of glucose in animals

  • Can have up to 600,000 glucose units

  • Mainly in liver and muscles

    • (1→4 and 1→6 links)


Cellulose

Cellulose

  • Polymer of glucose units

  • Found in plant cell walls

  • Linear polymer but has  (14)glycosidic linkages.

  • Not easily digested, a constituent of dietary fiber.


  • Login