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Carbohydrates B.3
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Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Jan 05, 2016

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Blanche Watkins
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Page 1: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Carbohydrates B.3

Page 2: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Introduction

• most abundant class of biological molecules

• range from simple sugars (glucose) to complex carbohydrates (starch)

Page 3: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Major functions (B.3.4)

• energy source– glucose converted into ATP– breads high in carbohydrates

• energy storage– glycogen stored in the liver

• precursors – necessary for molecules such as DNA

• dietary fiber– “roughage” is good

Page 4: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Describe the structural features of Monosaccharides (B.3.1)

• simplest sugars (single sugars)– all contain the empirical formula (CH2O)– contain a carbonyl group*, C=O

* a more generic term for a carbon double bonded to and oxygen

– contain at least two hydroxyl groups (-OH)

• can be straight chains or cyclic form• two common isomers of monosaccharides

(C6H12O6)•glucose•fructose

Page 5: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Draw the straight-chain and ring structural formulas of glucose and fructose. (B.3.2)

Page 7: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

H O

OH

H

OHH

OH

CH2OH

H

OH

H H O

OH

H

OHH

OH

CH2OH

H

H

OH

-D-glucose -D-glucose

23

4

5

6

1 1

6

5

4

3 2

H

CHO

C OH

C HHO

C OHH

C OHH

CH2OH

1

5

2

3

4

6

D-glucose (linear form)

Page 9: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)
Page 10: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Condensation of monosaccharides to form disaccharides and polysaccharides (B.3.3)

• example of a typical condensation reaction

A-OH + B-OH ===> H2O + A-O-B

Page 11: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

• requires enzymes• the hydroxyl (-OH) of two monomers are brought

together and the H of one and the OH of the other come together to make H2O

• the remaining O from one of the monomers bonds the two together in a bond called a glycosidic linkage

Page 12: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Disaccharides• double sugar (contains 2 monosaccharides)• three common disaccharides:

1. sucrose - common table sugar glucose + fructose

2. lactose - major sugar in milkglucose + galactose

3. maltose - product of starch digestion glucose + glucose

Page 14: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)
Page 15: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

+

Page 16: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)
Page 17: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)
Page 18: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Polysaccharides• starch- condensation of many α glucose molecules

• cellulose- condensation of many β glucose molecules

• glycogen- condensation of many α glucose molecules

= OH

Page 19: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Compare structural properties of starch and cellulose (B.3.5)

• longer chains of simple sugars made of glucose• serve principally as food storage and structural

molecules in plants• Two Types of Polysaccharides

1. Starches (plants)– polymers of glucose molecules

– serve as storage depots of glucose

– two forms

• amylopectin- insoluble, branched chains, up to millions of glucoses

• amylose- water soluble, straight chains, thousands of glucoses

Page 20: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

glucose polymer with

(14) linkages, and

branches formed by (16) linkages

glucose polymer

with only (14) linkages.

Page 21: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

2. Cellulose (plants)• most abundant polysaccharide on Earth• the major structural material of which plants are made

(wood and plant fibers)• insoluble in water, great strength and rigidity as

hydrogen bonding holds chains in a side by side alignment

• only has beta-1,4 linkage

Page 22: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

• plant cell walls are among the strongest of biological structures

• most organisms can’t break cellulose down into simple sugars because they don’t have the enzyme cellulase which is necessary to hydrolyze (break bonds using water) the glycosidic linkages

Page 23: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

Dietary fiber and its importance B.3.6-7

• dietary fiber is plant material that we ingest but are not able to digest

• passes through the gut relatively intact, as we do not possess cellulase enzymes capable of hydrolysing it– bacteria in our gut can digest it somewhat– example: cellulose

Page 24: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)
Page 25: Carbohydrates B.3. Introduction most abundant class of biological molecules range from simple sugars (glucose) to complex carbohydrates (starch)

• importance in our diet– helps “bulk” move through the large intestine

more easily• prevent constipation and diverticulosis (bulges in

the colon at weak places leading to pain)

• may prevent irritable bowel syndrome (IBS)

• may prevent hemorrhoids

– may cause a “full feeling” and therefore decrease chance of obesity

– may help prevent Crohn’s disease