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“ CARBOHYDRATES

201139189CANDICE PIENAAR

REFERENCES

1) http://www.slideshare.net/kleppingerb/catrbohydrates?qid=674cbdcc-2c94-43fa-8f43-ffdb057f65aa&v=qf1&b=&from_search=5

2) http://www.slideshare.net/obanbrahma/carbohydrates-30770508?qid=674cbdcc-2c94-43fa-8f43-ffdb057f65aa&v=qf1&b=&from_search=6

3) http://www.slideshare.net/mazz4/carbohydrates-28729095?qid=674cbdcc-2c94-43fa-8f43-ffdb057f65aa&v=qf1&b=&from_search=9

4) http://www.slideshare.net/syed_ismail/carbohydrates-28872311?qid=674cbdcc-2c94-43fa-8f43-ffdb057f65aa&v=qf1&b=&from_search=8

5) http://www.slideshare.net/gangadharchatterjee/carbohydrate-chemistry-27717759

CARBOHYDRATESIs an organic compound

σακχαρωνGreek “sakcharon” = sugar

LETS LEARN SOME GREEK!!!!The name glucose comes from the Greek word glykys (γλυκύς), meaning "sweet", plus the suffix "-ose" which denotes a sugar

4 chiral centers give 24 = the 16 stereoisomer s of hexose sugars. Chirality, or "handedness", Greek, (χειρ), kheir: "hand” chiral carbons are enantiomers

Alpha α and Beta β are letters in the Greek alphabet

Carbohydrates • Carbohydrates, or saccharides (saccharo is Greek for ―sugar) are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis.

• Carbohydrates include not only sugar, but also the starches that we find in foods, such as bread, pasta, and rice.

• The term ―carbohydrate comes from the observation that when you heat sugars, you get carbon and water (hence, hydrate of carbon).

Carbohydrates and Biochemistry•Carbohydrates are compounds of tremendous biological importance:–they provide energy through oxidation–they supply carbon for the synthesis of cell components–they serve as a form of stored chemical energy–they form part of the structures of some cells and tissues•Carbohydrates, along with lipids, proteins, nucleic acids, and other compounds are known as biomolecules because they are closely associated with living organisms.

glucose

is the building blockof carbohydrates

Importance of carbohydrates:

CHIEF SOURCE OF ENERGY

Types of Carbohydrates:

monosaccharide

disaccharide

polysaccharide

monosaccharide

MONOSACCHARIDES

CLASSIFICATION OF MONOSACCHARIDES

1- According to the number of carbon atoms: .Trioses, contain 3 carbon atoms.• Tetroses, contain 4 carbon atoms.• Pentoses, contain 5 carbon atoms.• Hexoses, contain 6 carbon atoms.• Heptoses, contain 7 carbon atoms.• Octoses. contain 8 carbon atoms.

Glucose (a monosaccharide)

Plants:

photosynthesis chlorophyll

6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose

(+)-glucose starch or cellulose

respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

monosaccharide

C6H12O6

Simple sugars that consist s only one (1) sugar molecule

Under monosaccharide:1. Glucose2. Fructose3. Galactose

monosaccharide

1. Glucose

Blood sugar; most important sugar in the bodies of both vertebrates and invertebrates

monosaccharide

2. Fructose

Corn sugar; sweetest form of sugar commonly found in fruits

monosaccharide

3. Galactose

Simplest sugar found in milk

Animals

plant starch (+)-glucose

(+)-glucose glycogen

glycogen (+)-glucose

(+)-glucose fats or aminoacids

respiration

(+)-glucose + 6 O2 6 CO2 + 6 H2O + energy

2. MONOSACCHARIDES

• Examples

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2. MONOSACCHARIDES

• Once a monosaccharide has been named as an aldose or a ketose, and the number of carbons has been designated, there are still several different isomeric forms for each.

• Each specific monosaccharide has a unique name.

• A prefix (D- or L-) is added to designate which of two possible isomeric forms is being referred to.

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disaccharide

disaccharide

C12H22O11

Pair of monosaccharide unitsGlucose + monosaccharide unit = disaccharide

Under disaccharide:1. Sucrose2. Lactose3. Maltose

OOHOH

FORMING DISACCHARIDES

C C

C

C O

C

H

OH

OHOH

OH

HH

CH2OH

H

H

CH2OH

C C

C

C O

C

H

OH

OHOH

OH

HH

CH2OH

H

H

C C

C

C O

C

H

OH

OH

OH

HH

CH2OH

H

H

C C

C

C O

C

H

OH

OH

OH

HH

CH2OH

H

H O

H H

GlycosidicBond This is a CONDENSATION

reaction, where a water molecule is lost.

Glucose

Maltose

disaccharide

1. Sucrose

Table sugar; glucose + fructose

disaccharide

2. Lactose

Milk sugar; glucose + galactose

disaccharide

3. Maltose

Malt sugar; glucose + glucose

polysaccharide

polysaccharide

Consists of chains of monosaccharide and disaccharide

Under polysaccharide:1. Starch2. Glycogen3. Cellulose

polysaccharide

1. Starch

Storage of glucose for plants

polysaccharide

2. Glycogen

Storage of excess sugar in animals; stored in liver and muscles

polysaccharide

3. Cellulose

Structural support of plants; known as “fiber”

Additional info:

monomer: a molecule that may react chemically to another molecule to form polymer; the simplest unit; repeating unit of polymer

polymer: a compound made up of several repeating units (monomer)

enzyme: speeds up chemical reaction

CLASSIFICATION:

1- Monosaccharides (simple sugars): They can not be hydrolyzed into simpler units. E.g. glucose, galactose,ribose

2- Oligosaccharides (oligo = few): contain from two to ten monosaccharide units joined in glycosidic bonds. e.g.

• disaccharides (2 units) e.g. maltose and sucrose,• trisaccharides (3 units).....etc.

3-Polysaccharides (poly = many): Also known as glycans. They are composed of more than ten monosaccharide units e.g. starch, glycogen, cellulose.....etc.

2- According to the characteristic carbonyl group (aldehyde or ketone group):

- Aldo sugars: aldoses:

Contain aldehyde group e.g. glucose, ribose, erythrose and glyceraldehydes.

- Keto sugars: ketoses:

Contain ketone group e.g. fructose, ribulose and dihydroxy acetone.

GLUCOSE FORMS A RING STRUCTURE

Note: functional group is on carbon one

TWO TYPES OF RING STRUCTURES FOR GLUCOSE

OH on carbon one:

BELOW the ring ABOVE the ring

The existence of - and -isomers:- leads to greater chemical variety is of importance in for example in

forming starch and cellulose

NOTE DIFFERENCE:

The main difference between glucose and galactose is that glucose is much sweeter than galactose.

13.4. REACTIONS--ADDITION

• Addition of an alcohol to an aldehyde:

• The product is called a hemiacetal (-OH and –OR attached to the same carbon).

• Hemiacetals are very reactive.

• They react with an additional alcohol molecule, losing –OH and adding another –OR.

40

H+

13.4. REACTIONS--ADDITION

• The final product is an acetal (2 –OR groups attached to one carbon).

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hemiacetal acetal

13.4. REACTIONS--ADDITION

• Ketones undergo analogous addition reactions with alcohols.

• The initial product is a reactive hemiketal (two –R groups, one –OH, and one –OR).

• An additional –OR group is added to the hemiketal to produce a ketal.

42hemiketal ketal

13.4. REACTIONS--ADDITION