Gülüzar Özbolat_Karbohidratlar

8/2/2019 Glzar zbolat_Karbohidratlar

1/58

1

Chapter 14 Carbohydrates

14.1

Carbohydrates

Copyright 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings


2/58

2

Carbohydrates

Carbohydrates are

A major source of energyfrom our diet.

Composed of the elementsC, H, and O.

Also called saccharides,which means sugars.



3/58

3

Carbohydrates

Carbohydrates

Are produced by photosynthesisin plants.

Such as glucose are synthesizedin plants from CO2, H2O, andenergy from the sun.

Are oxidized in living cells(respiration) to produce CO

2,

H2O, and energy.

Copyright 2007 by Pearson Education, IncPublishing as Benjamin Cummings


4/58

4

Types of Carbohydrates

The types of carbohydrates are

Monosaccharides, the simplest carbohydrates.

Disaccharides, which consist of two monosaccharides.

Polysaccharides, which contain manymonosaccharides.



5/58

5

Monosaccharides

Monosaccharides consist of

3 to 6 carbon atoms, typically.

A carbonyl group (aldehyde or ketone).

Several hydroxyl groups.


6/58

6

Aldoses

Aldoses are monosaccharides

With an aldehyde group.

With many hydroxyl (OH)

groups.triose(3 C atoms)

tetrose(4 C atoms)

pentose(5 C atoms)

hexose(6 C atoms)

O

CH aldose

HCOH

HCOH

CH2OH

Erythose, an aldotetrose


7/58

7

Ketoses

Ketoses are monosaccharides

With a ketone group.

With many hydroxyl (OH)

groups.triose(3 C atoms)

tetrose(4 C atoms)

pentose(5 C atoms)

hexose(6 C atoms)

CH2OH

C=O ketose

HCOH

HCOH

HCOHCH2OH

Fructose, a ketohexose


8/58

8

Learning Check

Identify each as aldo- or keto- and as tetrose, pentose,

or hexose:

A B

H

CH2OH

OHC

H

H

H

OH

OH

OH

C

C

CHC

O

CH2OH

HHO

CH2OH

O

H OHC

C

C


9/58

9

Solution

A. aldohexose

B. ketopentose


10/58

10

14.2

Structures of Monosaccharides



11/58

11

Fischer Projections

A Fischer projection

Is used to represent carbohydrates.

Places the most oxidized group at the top.

Shows chiral carbons as the intersection of verticaland horizontal lines.

Copyright 2007 by Pearson Education, Inc Publishing as Benjamin Cummings


12/58

12

D and L Notations

In a Fischer projection, the OH group on the Chiral carbon farthest from the carbonyl group

determines an L or D isomer.

Left is assigned the letter Lfor the L-isomer.

Right is assigned the letter Dfor the D-isomer.



13/58

13

Examples of D and L Isomers of

Monosaccharides

O

CH2OH

H OH

H OH

HO HOHH

C H

CH2OH

H OH

H OH

OHHHC

OH

O

CH2OH

HO H

H OH

H OH

HHO

C

D-glucose D-ribose L-galactose


14/58

14

Learning Check

Identify each as the D or L isomer.

A. B. C.

__-ribose __- threose __- fructose

CH2OHHO H

HO H

HHO

O

C H

CH2OHHO H

OHH

O

C H

CH2OH

H OH

H OH

HO H

O

CH2OH


15/58

15

Solution

Identify each as the D or L isomer.

A. B. C.

L-ribose L-threose D-fructose

CH2OH

HO H

HO H

HHO

O

C H

CH2OH

HO H

OHH

O

C H

CH2OH

H OH

H OH

HO HO

CH2OH


16/58

16

D-Glucose

D-glucose is

Found in fruits, cornsyrup, and honey.

An aldohexose with

the formula C6H12O6. Known as blood sugar

in the body.

The monosaccharide

in polymers of starch,cellulose, andglycogen. Copyright 2007 by Pearson Education, Inc

Publishing as Benjamin Cummings


17/58

17

Blood Glucose Level

In the body,

Glucose has anormal bloodlevel of 70-90

mg/dL. A glucose

tolerance testmeasures blood

glucose forseveral hoursafter ingestingglucose.

Copyright 2007 by Pearson Education, Inc Publishing as BenjaminCummings


18/58

18

D-Fructose

D-fructose

Is a ketohexoseC6H12O6.

Is the sweetestcarbohydrate.

Is found in fruitjuices and honey.

Converts toglucose in thebody.

H OH

CH2OH

C

HOH OH

HC

O

C

C

CH2OH

D-FructoseCopyright 2007 by Pearson Education, IncPublishing as Benjamin Cummings


19/58

19

D-Galactose

D-galactose is

An aldohexose C6H12O6.

Not found free in nature.

Obtained from lactose, adisaccharide.

A similar structure toglucose except for the

OH on C4.

H

H

H OH

CH2OH

C

HO

HO HC

OH

C

C

O

C H

D-Galactose


20/58

20

Learning Check

Draw the structure and Fischer projection of D-fructose.


21/58

21

Solution

CH2OHC=O

HO H

H OH

H OHCH2OH

Fischer projection

H OH

CH2OH

C

HOH OH

HC

O

C

C

CH2OH

D-Fructose


22/58

22

14.3

Cyclic Structures ofMonosaccharides

OH

OH

OHOH

CH2OH

O

Copyright 2007 by Pearson Education, IncPublishing as Benjamin Cummings


23/58

23

Cyclic Structures

Cyclic structures

Are the prevalent form of monosaccharides with 5 or6 carbon atoms.

Form when the hydroxyl group on C-5 reacts with thealdehyde group or ketone group.

O O


24/58

24

Cyclic Haworth Structures

Stable cyclic hemiacetals form

When the C=O group and the

OH are part of the samemolecule.

For hexoses, the hydroxyl groupon C-5 reacts with the aldehydegroup or ketone group.

The cyclic structure of a D-isomerhas the last CH2OH grouplocated above the ring.

CH2OHO


25/58

25

Drawing the Cyclic Structure for

Glucose

STEP 1 Number the carbon chain and turn clockwise toform a linear open chain.

HHO

H

CH2OH

OHCH

H

OH

OH

C

C

C

OH

C1

2

3

4

5

6

6 5 4 3 2 1

H

OHH

OH

C

H H

OH OH

C C C

H

O

CHOCH2


26/58

26

Cyclic Structure for Glucose

STEP 2 Bend the chain tomake a hexagon

Bond the C5O to C1. Place the C6 group above

the ring.

Write theOH groups onC2 and C4 below the ring.

Write the

OH group on C3above the ring.

Write a newOH on C1.

6

5

4 1

3 2 OH

OH

OHOH

CH2OH

O


27/58

27

Cyclic Structure for Glucose (cont)

-D-glucose -D-glucose

STEP 3 The newOH on C1 is drawn Down for the anomer. Up for the anomer.

O

CH2OH

OH

OH

OH

OH

O

CH2OH

OH

OH

OH

OH


28/58

28

Summary of the Formation of Cyclic

Glucose



29/58

29

-D-Glucose and -D-Glucose inSolution

When placed in solution,

Cyclic structures open and close.

-D-glucose converts to -D-glucose and back.

There is only a small amount of open chain.

-D-glucose D-glucose (open) -D-glucose

(36%) (trace) (64%)

OH

OH

OHOH

CH2OH

OOH

OH

OHOH

CH2OH

OOH

CH2OH

OH

OC

H

OH

OH


30/58

30

Cyclic Structure of Fructose

Fructose Is a ketohexose.

Forms a cyclic structure.

Reacts the OH on C-5 with the C=O on C-2.

D-fructose -D-fructose-D-fructose

OCH

2OH

OH

OH

OH

CH2OH

OOH

CH2

OH

OH

OH

CH2OH

H OH

H OH

HHO

O

CH2OH

C

C

C

C

CH2OH


31/58

31

Learning Check

Write the cyclic form of -D-galactose

H

H

H OH

CH2OH

C

HO

HO HC

OH

C

C

O

C H


32/58

32

Solution

-D-galactose

OH

OH

OH

OH

CH2OH

O


33/58

33

14.4Chemical Properties of

Monosaccharides



34/58

34

Reducing Sugars

Reducing sugars

Are monosaccharides with a carbonyl group thatoxidizes to give a carboxylic acid.

Undergo reaction with Benedicts reagent (Cu2+) to

give the corresponding carboxylic acid.

Include the monosaccharides glucose, galactose,and fructose.


35/58

35

Oxidation of D-Glucose

+ Cu2O(s)

D-gluconic acidD-glucose

+ Cu2+

H OH

H OH

HHO

H OH

O

OH

CH2OH

C

C

C

C

C

H OH

H OH

HHO

H OH

O

H

CH2OH

C

C

C

C

C

[O]

Benedictsreagent

Glucose is a reducingsugar

Cu

+

(reducedform)

Glucose is oxidizedto a carboxylic acid


36/58

36

Reduction of Monosaccharides

The reduction ofmonosaccharides

Involves the carbonylgroup.

Produces sugaralcohols called alditols.

Such as D-glucosegives D-glucitol alsocalled sorbitol.

D-Glucitol



37/58

37

Learning Check

Write the products of the oxidation and reduction of

D-mannose.

H

O

CH2OH

H OH

H OH

HO H

HHO

C

D-mannose


38/58

38

Solution

Write the products of the oxidation and reduction of

D-mannose.

H

O

CH2OHH OH

H OH

HO H

HHO

COH

O

CH2OH

H OH

H OH

HO H

HHO

C

CH2OH

H OH

H OH

HO H

HHO

CH2OH

Reduction Oxidation

D-mannitol D-mannose D-mannonic acid


39/58

39

14.5 Disaccharides



40/58

40

Important Disaccharides

A disaccharide

Consists of two monosaccharides.

Monosaccharides Disaccharide

Glucose + glucose maltose + H2OGlucose + galactose lactose + H2OGlucose + fructose sucrose + H2O


41/58

41

Maltose

Maltose is

A disaccharide also known as malt sugar.

Composed of two D-glucose molecules.

Obtained from the hydrolysis of starch. Linked by an -1,4-glycosidic bond formed from the

OH on C1 of the first glucose and OH on C4 ofthe second glucose.

Used in cereals, candies, and brewing.

Found in both the - and - forms.


42/58

42

Formation of Maltose



43/58

43

Lactose

Lactose

Is a disaccharide of -D-galactose and - or-D-glucose.

Contains a -1,4-glycosidic bond.

Is found in milk andmilk products.

-form



44/58

44

Sucrose

Sucrose or table sugar

Is obtained from sugar cane and sugar beets.

Consists of -D-glucose and -D-fructose..

Has an ,-1,2-glycosidic bond.

-D-glucose

-D-fructoseCopyright 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings


45/58

45

Learning Check

Write the structures and names of the two

monosaccharides that form when sucrose is

hydrolyzed.


46/58


47/58

47

Sweeteners

Sugars and artificial

sweeteners

Differ insweetness.

Are compared tosucrose (tablesugar), which isassigned a value

of 100.

TABLE 15.2

60 000


48/58

48

Learning Check

Identify the monosaccharides in each of the following:

A. lactose

(1) -D-glucose (2) -D-fructose (3) -D-galactose

B. maltose


C. sucrose



49/58

49

Solution

Identify the monosaccharides in each of the following:

A. lactose

(1) -D-glucose (3) -D-galactose

B. maltose

(1) -D-glucose

C. sucrose(1) -D-glucose (2) -D-fructose


50/58

50

14.6

Polysaccharides



51/58

51

Polysaccharides

Polysaccharides

Are polymers of D-glucose.

Include amylose andamylopectin, starches made of

-D-glucose. Include glycogen (animal starch

in muscle), which is made of -D-glucose.

Include cellulose (plants andwood), which is made of

-D-glucose.

-D-glucose

O

CH2OH

OH OH

OH

OH

S f A l d


52/58

52

Structures of Amylose and

Amylopectin

Copyright 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings


53/58

53

Amylose

Amylose is

A polymer of -D-glucose molecules.

Linked by -1,4glycosidic bonds.

A continuous(unbranched)chain.



54/58

54

Amylopectin

Amylopectin

Is a polymer of -D-glucose molecules.

Is a branched-chain

polysaccharide.

Has -1,4-glycosidicbonds between theglucose units.

Has -1,6 bonds tobranches.



55/58

55

Glycogen

Glycogen

Is the polysaccharidethat stores -D-glucosein muscle.

Is similar toamylopectin, but ismore highly branched.



56/58

56

Cellulose

Cellulose

Is a polysaccharideof glucose units inunbranched chains.

Has -1,4-glycosidicbonds.

Cannot be digestedby humans because

humans cannotbreak down -1,4-glycosidic bonds.



57/58

57

Learning Check

Identify the polysaccharides and types of glycosidic

bonds in each of the following:

A. B. C.


58/58

58

Solution

A. Cellulose -1,4-glycosidic bonds

B. Amylose -1,4-glycosidic bondsAmylopectin -1,4-and -1,6-glycosidic bonds

C. Glycogen -1,4-and -1,6-glycosidic bonds

(more branched than amylopectin)

Documents

Gülüzar Özbolat_Karbohidratlar