Ch. 19 Carbohydrates

7/31/2019 Ch. 19 Carbohydrates

1/35

Ch. 19

Carbohydrates

Milbank High School


2/35

Chapter Objectives

1. What are carbohydrates? What is thedifference between mono-, di-, andpolysaccharides?

2. What are the structures of the most commonlyoccurring monosaccharides? Be able to classifythem as aldoses or ketoses and as trioses,pentoses, or hexoses.

3. What is the difference between a D and an Lsugar?


3/35

Chapter Objectives

4. What is mutarotation? How does itoccur?

5. What are the structures of sucrose,lactose, and maltose, the most commondisaccharides? What monosaccharidesmake up each of these disaccharides?

6. Compare and contrast starch, glycogen,and cellulose.


4/35

What is Biochemistry?

The chemistry of molecules and reactionsfound in living organisms


5/35

Carbohydrates

Carbon hydrates Compounds containing carbon, hydrogen, and

oxygen Starches and fibers (complex carbohydrates) Sugars Cellulose

Contain hydroxyl groups And either an aldehyde or ketone Known as polyhydroxy aldehydes or ketones


6/35

Monosaccharides

Simple carbohydrates Cannot be further hydrolyzed

Contain 3-7 carbons Readily dissolve in water Can link together to form more complex

carbohydrates Disaccharides Trisaccharides Polysaccharides


7/35

Sec. 19.1General Terminology and

Stereochemistry Named using IUPAC to name

monosaccarides Name the number of carbons, then add-ose Trios, tetrose, pentose, hexose etc

If aldehyde is attached: aldotetrose If ketone is attached: ketotetrose


8/35

Common monosaccharides

Glucose Fructose


9/35

Enantiomers

Molecules that are nonsuperimposablemirror images of each other

Have identical physical properties exceptone: They rotate plane-polarized light in opposite

directions


10/35

Trioses

Simplest sugars Two enantiomers

D sugars L sugars


11/35

Sec. 19.2Hexoses

Aldohexoses 16 isomers (8 enantiomeric pairs) 3 most common:

Glucose, mannose, galactose

Ketohexoses 8 isomers

fructose


12/35

Glucose

Most abundant sugar in nature Fruits

grape sugar Dextrose b/c it is dextrorotatory

Carbs converted to glucose Produces energy for our cells

Circulating carbohydrate Blood sugar


13/35

Glucose Cont

Synthetically made by the hydrolysis of starch Corn starch

corn sugar


14/35

Mannose

Component of polysaccharide mannan Berries Vegetable ivory endosperm

Differs from glucose at only one point


15/35

Galactose

Needed by human body for synthesis of lactose In mammary glands

Also important constituent of theglycolipids Occur in brain in myelin sheath of nerve cells brain sugar Differs from glucose at only one point


16/35

Fructose

Only naturally occurring ketohexose Also similar structure to that of glucose

Found in honey (40%) Formed in prostate gland

Energy source for spermatozoa


17/35

Artificial Sweeteners

High-intensity sweeteners Manufactured in place of mono- and

disaccharides Saccharin

1890s 500-700 times sweeter than sucrose Carcinogenic


18/35

Artificial Sweeteners

Aspartame 1967 160 times sweeter than sucrose Used in diet soda

Sucralose 1998 600 times sweeter than sucrose Passes through body unchanged

S 19 3


19/35

Sec. 19.3Cyclic Structures of

Monosaccharides


20/35

Sec. 19.4Properties of Monosaccharides

Crystalline solids at room temperature Quite soluble in water

Converted to anions when Tollens andBenedicts reagents are used Used in simple and rapid diagnostic tests

for the presence of glucose in blood or urine


21/35


22/35

Sec. 19.5Disaccharides

Composed of two monosaccharide units Joined when one monosaccharide reacts

with the hydroxyl group of a secondmonosaccharide

Forms a carbon-oxygen-carbon linkage glycosidic linkage


23/35

Maltose

Occurs in sprouting grain Forms malt in the manufacture of beer

malt sugar

About 30% as sweet as sucrose Body cant utilize it directly

Must be broken down by enzymes


24/35

Lactose

Milk sugar Occurs in the milk of humans, cows, and other

mammals

Human milk: 7.5% lactose Cows milk: 4.5% lactose Synthesized only by mammary tissue in nature

Commercial produced from whey (from cheese) 1/6 th as sweet as sucrose


25/35


26/35

Lactose Intolerance Cont

Foods can be treated with lactase Lactaid

Tablets taken orally with dairy foods to assistin their digestion


27/35

Sucrose

Beet sugar, cane sugar, table sugar, or just sugar

Largest selling pure organic compound inthe world

Obtained from sugar canes and beets Average American: 100 pounds of sucrose

every year


28/35

Sucrose Cont

May cause cancer, heart disease,migraine headaches, hyperactivity inchildren, obesity, and tooth decay


29/35

Sec. 19.6Polysaccharides

Most abundant carbs in nature Store energy and make up plant cells

High-molar mass Starch, glycogen, and cellulose


30/35

Starch

Most important source of carbs in the humandiet

More than 50% of our carb intake

Granule form Storage

Potatoes: 15%

Wheat: 55% Corn: 65% Rice: 75%


31/35

Starch Cont

Mixture of amylose and amylopectin Amylose: 60-300 glucose units per chain

Amylopectin: 300-6000 glucose units

Commercial starch

White powder Stamps, envelopes, labels (sticky upon wetting)


32/35

Glycogen

animal starch Reserve carb of animals

All mammalian cells contain glycogen Liver and skeletal cells the most Used when fasting


33/35

Cellulose

Fibrous carb found in all plants Cell walls

Most abundant of all carbs Makes up 50% of all carbon in thevegetable world

Much hydrogen bondinginsoluble inwater


34/35

Cellulose Cont

Cant be digested by humans Herbivores contain special enzymes to

digest it and use it for energy Termites


35/35

Dietary Fiber

Insoluble fiber (cellulose) Reduces risk of colon cancer and heart

disease (reduces cholesterol) ADA recommends 20-35 g a day

Most Americans get 14-15 g a day

Documents

Ch. 19 Carbohydrates