b3 carbohydrates

All B3 ObjectivesB.3.1: Describe the structural features of monosaccharides.B.3.2: Draw the straight-chain and ring structural formulas of

glucose and fructose.B.3.3: Describe the condensation of monosaccharides to form

disaccharides and polysaccharides.B.3.4: List the major functions of carbohydrates in the human

body.B.3.5: Compare the structural properties of starch and

cellulose, and explain why humans can digest starch but not cellulose.

B.3.6: State what is meant by the term dietary fibre.B.3.7: Describe the importance of a diet high in dietary fibre.

• Monosaccharides have an empirical formula of CH2O– Many isomers

• Ex: Glucose and fructose have same molecular formula (C6H12O6) but have different structures

Glucose

Objective Objective B.3.1B.3.1

Describe the structural features of monosaccharides

• Made up of covalent bonds• Contain one carbonyl group (C=O)• Contain at least two hydroxyl groups (-OH)• Ex. Glucose, fructose, and galactose


Describe the structural features of monosaccharides


Glucose: Straight-Chain Formula• 6-carbon backbone• Carbons 1 and 5 are connected by

Oxygen• Each carbon is bonded to a

hydroxide (except for the 5th)– Carbon 3 has a hydroxide on the left

– Carbons 2, 4, 5 and 6 have hydroxides on the right

• All other bonds are occupied with Hydrogen

Draw the straight-chain and ring structural formulas of glucose and fructose


Glucose: Ring-Structure Formula• Should be familiar (biology class)• Hexagon-shape with 5 Carbons

and Oxygen in the top right corner

• Each carbon bound to 1 hydrogen and 1 hydroxide– Hydrogen is on top, hydroxide

is on bottom (except Carbon 3)– Carbon 5 has another carbon(6)

instead of a hydroxide– Carbon 6 has 2 hydrogens and

1 hydroxide


The ring-structure forms when glucose is dissolved in water and undergoes and internal reaction

Alpha (α) vs. Beta (β)•Alpha (α) structure has the hydroxide group on the bottom bonded with carbon 1 in the ring structure. (AB)

•Beta (β) structure has the OH group on the top bonded to carbon 1 in ring structure. (BT)

•The alpha- and beta- variations only occur in the ring structure




Fructose: Straight-Chain Formula

• 6-carbon backbone

• Carbon 1 and Carbon 6 both have two hydrogens and 1 hydroxide

• Carbon 2 has one single Oxygen

• Carbons 3, 4, and 5 all have one hydrogen, one hydroxide

– Carbon 3 is flipped (hydroxide on the left)



Fructose: Ring-Structure Formula• Pentagon-shape with Oxygen at the

top center and 4 other Carbons• Two bottom Carbons have

one hydrogen and one hydroxide

• The two side Carbons haveone hydroxide and anothercarbon

• Hanging carbons have twohydrogens and one hydroxide


The ring-structure forms when fructose is dissolved in water and undergoes and internal reaction



Alpha (α) vs. Beta (β)•Similar to the Alpha and Beta structures of glucose•ARB (Alpha (α): on the right of C2 for straight-chain, on the bottom for ring structure)•BLT (Beta (β): on the left of C2 for straight-chain, on the top for ring structure)

•Note that the fructose

variations occur at C2, and not C1.


• Monosaccharides can join together and form a disaccharide through condensation (dehydration synthesis)

• Hydroxyl (-OH) groups of monosaccharides (or disaccharides)

• Maltose Example (glucose + glucose)– C6H12O6 + C6H12O6 C12H22O11 + H2O– Hydrogen from one glucose –OH group and OH from

another glucose’s –OH group are lost as water

– Remaining oxygen up bridges the monomers forming a disaccharide

– 14 linkage utilizing covalent bond (glycosidic bond)

Describe the condensation of monosaccharides to form disaccharides and polysaccharides.



maltose

glucose glucose

+ H2O

H H


• Monosaccharide examples:– Glucose, Fructose, Galactose

• Disaccharide examples:– Lactose, Maltose, Sucrose

• Polysaccharide examples:– Starch, Glycogen, Cellulose



• Disaccharide Structures:– Lactose (in milk)

• 1 alpha-glucose + 1 beta-galactose


– Maltose (starch digestion product)• 2 alpha-glucose

– Sucrose (canesugar, common in food)• 1 alpha-glucose + 1 beta-fructose

Sucrose


• Major functions:–Energy Source–Energy Storage–Important for Other Molecules

List the major functions of carbohydrates in the human body


• Energy Source: Glucose–Glucose is a monosaccharide which

helps provide the body with energy–Glucose is oxidized in respiration to

help form ATP energy for the body to use


http://www.individualsole.com/wp-content/uploads/2010/05/SpSu10_Running_02035_ipod-540x360.jpg



http://drpinna.com/wp-content/uploads/2010/08/glucose.gif


• Energy Storage: Glycogen– Energy, in animals, is stored in the

form of Glycogen (in the liver muscles)

– Glycogen is formed through Glycogenesis when there’s an abundance of glucose in the body

– The polysaccharide Glycogen breaks down through Glycogenolysis when more energy is needed


http://findstorageauctionriches.com/IMAGES/self-storage-units.jpg



http://themedicalbiochemistrypage.org/images/glycogen.jpg


• Carbs are Important for Other Molecules!– Carbs can be precursors to the formation of

other molecules– EX. Glucose– Glucose is needed to produce Vitamin C ,

proteins, and in forming disaccharides and polysaccharides

– In Glycolysis, glucose undergoes phosphorylation which allows it to be a precursor

– Carbs are also involved in structure/support in plants especially (EX. Cellulose which is formed from glucose)


http://upload.wikimedia.org/wikipedia/commons/8/81/Ascorbic_acid_structure.png

Ascorbic Acid (Vitamin C)


Compare the structural properties of starch and cellulose, and explain why humans can digest starch but not cellulose.

•Cellulose and Starch are both polymers of glucose

•The ring structure of glucose has two orientations

• α- Glucose

•OH group on the carbon 1 and the CH2OH group on the carbon 5 point in opposite directions

•β - Glucose

• OH group and CH2OH group point in the same direction

– Starch• Polysaccharide

– Created with a chain α- Glucose units– Bridging O atom is on the opposite side of the

CH2OH group • Serves as food storage in plants

– Corn, potatoes, wheat, and rice contain starch• Two forms of Starch

– Amylose» Straight chain polymer between the 1,4

carbons of the α- Glucose units (unbranched)

– Amylopectin » Branched structure that has both α- 1,4

linkage and α- 1,6 linkage– The two forms of starch allow it to be a relatively

compact spiral structure stored as starch grains in plant cells.



• Cellulose

– Polysachharide

– Created with a unbranched chain β - Glucose units

– Bridging O atom is on the same side as the CH2OH group

– Β- 1,4 linkage

– forms uncoiled linear chains due to the “upside down” alternating glucoses

– Hydrogen Bonds

– These form cables known as microfibrils which are rigid and give support to plants and make wood a useful building material



• Enzymes that break down starch cannot always break down cellulose because of their structural differences

• In humans, starch can be hydrolyzed to glucose and oxidized into energy– Cellulose passes through the body unchanged– Some animals and bacteria contain enzymes to digest cellulose as a food source– Cellulase breaks down the beta glycosidic bonds. Humans do not produce this

enzyme




• Dietary fibre is mainly plant material – Characteristics:

• Can’t be hydrolysed (digested) by enzymes in the human digestive tract

• may be digested by microflora in the gut

• Examples:– Cellulose– Hemicellulose– Lignin– Pectin

State what is meant by the term dietary fibre.


• Dietary fiber passes through the body without being changed or digested much.

• Aids the health of the large intestine by stimulating the production of mucous and helping the other products of digestion to pass out of the body more easily.

• Foods that are high in fiber: bran, dried herbs, spices, and peppers, soy beans, dark chocolate, and nuts.

• Prevents:– Constipation– Obesity– Crohn's disease– Hemorrhoids– Diabetes mellitus

Describe the importance of a diet high in dietary fiber.

References• http://www.elmhurst.edu/~chm/vchembook/540carbohy

drates.html• http://ibchem.com/IB/ibnotes/brief/pdf/optB.pdf• http://www.chem.purdue.edu/courses/chm333/Fall

%202009/Lectures/Fall%202009%20Lecture%2028.pdf• http://www.mansfield.ohio-state.edu/~sabedon/

biol1025.htm• http://www.3dchem.com/molecules.asp?ID=423• http://www.edinformatics.com/math_science/

science_of_cooking/glucose.htm• http://www.elmhurst.edu/~chm/vchembook/

547cellulose.html

http://www.elmhurst.edu/~chm/vchembook/540carbohydrates.html

http://www.elmhurst.edu/~chm/vchembook/540carbohydrates.html

b3 carbohydrates

Education

maltose glucose glucose

glucose c

hydroxide carbon

glucose glucoseis

glucose oh group

ring structure objective

hydroxide hydrogen

beta alpha structure