carbono inicial

EL CARBONO, COMPONENTE ESENCIAL

DE LAS CÉLULAS

Mauricio morenobogota2016

Importancia del carbono

El Carbono permea todo el mundo viviente— desde la organización estructural de las células, pasando por los requerimientos energéticos, hasta la conservación de la información genética. El carbono es un condicionamiento para la existencia de la

biosfera .

Compuestos orgánicos

El Hidrógeno y otros elementos se unen covalentemente al carbono para formar en los seres vivos:

CarbohidratosLipidosProteínasAcidos nucleicos

El átomo de carbono

En su último nivel posee cuatro electrones; pudiendo tener 8.

Cada átomo de carbono puede unirse máximo con cuatro elementos compartiendo un par de electrones.

Los átomos de carbono se pueden unir formando

cadenas lineales, ramificadas o anillos.

La principal característica es su capacidad de unirse con otros átomos de carbono y de otros elementos y formar millones de compuestos.

Glucosa

DIFERENTES MODELOS DE LAMOLECULA DE HEMOGLONINA

Ball-and-stick model Space-filling model

Ribbon model

•Configuración electrónica del carbono

7

ORBITALES “S”

ORBITALES “P”

•Clasificación de orbitales híbridos:

• Orbitales hibridos sp

• Orbitales hibridos sp2

• Orbitales híbridos sp3

ORBITAL HÍBRIDO sp3•Cuando se mezcla un orbital “s” con

tres orbitales “p”, de la misma subcapa se forman 4 orbitales híbridos “sp3“

(ese pe tres).

ORBITALES HIBRIDOS

El átomo de carbono

METANO: LA SUSTANCIA ORGÁNICA MÁS SIMPLE.

Structural formula

Ball-and-stick model

Space-filling model

HH

H

H

C

ORBITAL HÍBRIDO sp2

Siempre que se mezcla cierto número de orbitales atómicos se obtiene el mismo número de orbitales híbridos. Cada uno de éstos es equivalente a los demás pero apuntan en dirección distinta. Cuando se mezclan un orbital “s” con dos orbitales

“p, se forman 3 orbitales híbridos “sp2.“

ORBITALES HIBRIDOS

Orbital Híbrido “ sp“ • Esta hibridación ocurre cuando se

mezcla el orbital “s” y uno de los orbitales “p”, para generar dos

nuevos orbitales: Ejemplo BeF2

ORBITALES HIBRIDOS

GRUPOS FUNCIONALESSon átomos o grupos de átomos que se unen covalentemente a una cadena carbonada dandole diferentes propiedades.

- CH3 Grupo metilo

Grupo Hidroxilo - OH

Grupo Amino - NH3+

Grupo Carboxilo- COOH

Grupo Fosfato- PO3-

Grupo Sulfhidrilo- SH

HIDROCARBUROS

HIDROCARBUROS ALIFATICOS

ALCANOS

ACETILENO

AROMATICOS

ALCOHOLES

ALDEHIDOS Y CETONAS

ACIDOS CARBOXILICOS

ACILOS

ESTERES

ETERES

AMINAS

AMIDAS

FENOLES

NITRILOS

POLIFUNCIONALES

CARBOHIDRATOS

LIPIDOS

NUCLEOTIDOS

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Hidrocarburos• Compuestos de carbono e hidrogeno.

• Saturados (alcanos) los elementos unidos al carbono lo hacen a través de un enlace simple.

• Formula general [CnH2n+2] H C

H

H

C

H

H

H

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• Insaturados: Contienen enlaces carbono-carbono de tipo multiple (doble o triple)

H C

H

H

C

H

CH

H

76

Alcanos: hidrocarburos saturados

• Hidrocarburos saturados, CnH2n+2 – “Saturados” porque ellos no pueden unir

más átomos de hidrogeno.

77

Alcanos: hidrocarburos saturados • Hidrocarburos son moleculas compuestas de carbono

e hidrogeno.– Cada carbono forma cuatro enlaces químicos.– Un hidrocarburo saturado solo contiene enlaces sencillos

C – C y sus moléculas contienen el máximo número de átomos de H.

– Los hidrocarburos saturados son llamados ALCANOS

78

Metano es una molécula tetraedrica

79

Estructura de Lewis para el etano.

81

Propano

82

Butano

83

Los 10 “Normales” AlcanosNameName FormulaFormula M.P.M.P. B.P.B.P. # Structural Isomers# Structural Isomers

• Methane CH4 -183 -162 1

• Ethane C2H6 -172 -89 1

• Propane C3H8 -187 -42 1

• Butane C4H10 -138 0 2

• Pentane C5H12 -130 36 3

• Hexane C6H14 -95 68 5

• Heptane C7H16 -91 98 9

• Octane C8H18 -57 126 18

• Nonane C9H20 -54 151 35

• Decane C10H22 -30 174 75

C1 - C4 are Gases C1 - C4 are Gases at Room Temperatureat Room Temperature

C5 - C16 are Liquids C5 - C16 are Liquids at Room Temperatureat Room Temperature

84

Reglas de la IUPAC para nombrar alcanos

• Nombrar la cadena principalNombrar la cadena principal• Numerar los átomos de carbono de la cadena Numerar los átomos de carbono de la cadena

principal empezando por el más cercano a las principal empezando por el más cercano a las ramificacionesramificaciones

• Nombrar las ramificaciones con la teminación ilo, Nombrar las ramificaciones con la teminación ilo, ejemplo metilo, etilo, propilo etc.ejemplo metilo, etilo, propilo etc.

• Cuando hay más de una ramificación nombrarlas en orden alfabetico

• Finalmente usar prefijosprefijos para indicar multiples ramificaciones.

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1. Para alcanos después del butano, agregar-ano a la raíz griega del número de átomos de carbonos de la cadena más larga .

C-C-C-C-C-C : hexano2. Sustituyentes alquilo: cambiar-ano por

-ilo. -C2H5 es el etilo.

87


3.La posición de los sutituyentes se especifica con la numeración.

C C-C-C-C-C-C

3-metil-hexano Empezar desde el extremo más cercano

a la numeración.4. Nombrar los sutituyentes en orden

alfabetico y usando los prefijos di-, tri- etc.

89

Isomeros estructurales• Isomeros: moléculas que

tienen la misma formula molecular, pero diferente formula estructural CH3

CH2CH2

CH2CH3

CH3

CH2CH

CH3

CH3

n-pentano, C5H12

2-metilbutano, C5H12

90

Ejemplo : 2,2-dimetilpentano2,2-dimetilpentano

heptanoheptano

CH31

CCH23

CH24

CH35

CH3

CH3

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Ejemplo: 3-etil-2,4-dimetilheptano3-etil-2,4-dimetilheptano

3-etil-5-metiloctano

CH3

CHCH

CHCH2

CH2CH3

CH2CH3

CH3 CH3

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Reacciones de los alcanos

• Reacciones de combustion 2C4H10 + 13 O2 8CO2 + 10 H2OReacciones de sustituciónReacciones de sustitución

CHCl Cl CCl HClh3 2 4

CH4 + Cl2 CH3Cl + HCl

CH3Cl + Cl2 CH2Cl2 + HCl

CH2Cl2 + Cl2 CH Cl3 + HCl

93

Reacciones de deshidrogenaciónReacciones de deshidrogenación

CH3CH3 CH2 CH2 + H2

Etileno

94

Ciclo alcanosCiclo alcanos

• Formación de anillos, CnH2n

CH3

CH2CH3 CH2

CH2

CH2

n-propaneC3H8

cyclopropaneC3H6

60° bond angleunstable!!

109.5° bond angle

95

Ciclohexano –conformaciones de silla y bote• El Ciclohexano no es una molécula plana. • El bote y la silla (99%) son dos conformaciones

96

Alquenos y alquinos

Alquenos: hidrocarburos que contienen dobles enlaces carbono-carbono. [CnH2n]

C=C EtenoCC=C propeno

Alquinos: hidrocarburos que contienen u triple enlace carbono-carbono. [CnH2n-2]

C C EtinoCCCCC 2-pentino

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Nomenclatura para los Alquenos

1.La cadena principal debe contener el doble enlace, al nombarla debe terminar en -eno

C2H4; CH2=CH2 eteno

2. Cuando hay más de tres carbonos, el doble enlace se indica con el número con el número más bajo del carbono del enlacemás bajo del carbono del enlace C=CCC 1-buteno

98

Isomeros de los Alquenos:Cis y Trans

El doble enlace no permite los giros alrededor del mismo.

CH3 CH3 CH3

CH = CH CH = CH

cis trans CH3

99

Reacciones de adición

100

Hidrogenación

H H H H Ni

H–C=C–H + H2 H–C–C–H

H H

eteno etano

CHCH33-CH-CH33

101

Halogenacion

H H H H

NiH–C=C–H + Cl2 H–C–C–H

Cl Cl

eteno dicloroetano

102

Reacciones de Halogenación

CH2 CHCH2CH2CH2 + Br2

CH2Br CHBrCH2CH2CH2

1,2-dibromopentano

1-penteno

103

Alquinos, CnH2n–2

Triple enlace Carbono-carbono Nombres terminados en -ino

HCCH etino(acetileno)

HCC-CH3 propino

105

1 2 3 4

CH2=CHCH2CH3 1-buteno

CH3CH=CHCH3 2-buteno

CH3CHCHCH3 2-butino

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Preguntas

Cuál es el nombre de los siguientes compuestos:

A. CH3CH2CCCH3

CH3

B. CH3C=CHCH3

2-pentino

2-metil-2-buteno

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Preguntas

c.

CH3CH2C CCHCH2CH3CH2CH3

1 2 3 4 5 6 7

5-etil-3-heptino

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Hidrocarburos aromaticos

• Ciclos que contienen enlaces sencillos y dobles alternados. – Se llaman “aromaticos” (por el aroma

que generan).– La presencia de la alternacia de

enlaces sencilos y dobles le confiere propiedades particulares como participar en reacciones de sustitución y no de adición.

109

Estructuras de Lewis para el benceno

110

Benzene C6H6

sp2

sp2sp2

111

Shorthand notation for benzene rings

112

The bonding in the benzene ring is a combination of different Lewis structures.

REACCIONES DE SUSTITUCION DEL BENCENO

114

116

Nomenclatura de los derivados del benceno

117

Sistemas Aromaticos más complejos

118

Halogenuros de alquilo

Son alcanos en los cuales un hidrogeno ha sido reemplazado por un halogeno(F, Cl, Br, or I)

CH3Br bromometano BrCH3CH2CHCH3 2-bromobutano

Cl clorociclobutano

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Nomenclatura

bromociclopentano

1,3-diclorociclohexano

Br

Cl

Cl

1 2 3

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Nomenclatura

El nombre del siguiente compuesto es:Cl CH3

CH3CH2CHCH2CHCH3

1) 2,4-dimetilhexano2) 4-cloro-5-metilhexano3) 4-cloro-2-metilhexano

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Alcoholes: R–OH • El grupo hidroxilo –OH hace al alcohol polar

y puede formar puentes de hidrogenopuentes de hidrogeno. Lo Lo hace soluble en aguahace soluble en agua

• El Etanol es producto de la fermentacion

yeastC6H12O6

Glucosa2CH3CH2OHEtanol + 2 CO2

CO + 2H2O CH3OH Metanol

• El metanol es producto de la hidrogenacion industrial del monoxido de carbono

122

Usos de los alcoholes• Metanol es usado para la síntesis de

adhesivos, fibras, plasticos y combustble para motor.

• El metanol es toxico para los humanos y puede causar ceguera y muerte.

• El Etanol se le adiciona a la gasolina para formar gasohol. Es usado como solvente.

• Producción comercial del etanol: CH2=CH2 + H2O CH3CH2OH

123

Clases de alcoholes

R CH2OH Primary alchol

CHOHR'R

Secondary alcohol

CR'R

R"OH Tertiary alcohol

Los alcoholes se pueden clasificar de acuerdo al numero de carbonos unidos al carbono dondenumero de carbonos unidos al carbono donde esta el grupo –OH.

124

Nombrando los Alcoholes

En la IUPAC la terminación ano del alcano es reemplazada por -ol.

CH4 metano

CH3OH metanol (alcohol metilico)

CH3CH3 etano

CH3CH2OH etanol (alcohol etilico)

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OH

Phenol(Aromatic alcohol)

126

CH3CH2CH2OH 1-propanol

OH CH3CHCH3 2-propanol

CH3 OH CH3CHCH2CH2CHCH3 5-metil-2-hexanol5 2

127

OH CH3CHCH3

2-propanol (alcohol isopropilico)

HO-CH2-CH2-OH

1,2-etanodiol1,2-etanodiol (etilenglicol) OH

glicerol HO-CH2-CH-CH2OH

128

A. OH

CH3CHCHCH2CH3

CH3

OHB.

3-metil-2-pentanol

Ciclobutanol

129

Reacciones de los alcoholes

CombustionCH3OH + 2O2 CO2 + 2H2O + Energía

Deshidratacion H OH calor H-C-C-H H-C=C-H + H2O

H H H H alcohol alqueno

130

Ethers

• Contain an -O--O- between two carbon groups• Simple ethers named from -yl names-yl names of the

attached groups and adding adding etherether.

CH3-O-CH3 dimethyl ether

CH3-O-CH2CH3 ethyl methyl ether

131

Aldehydes and Ketones

In an aldehyde, an H atomH atom is attached to a carbonyl group

O carbonyl group CH3-C-HIn a ketone, two carbon groupstwo carbon groups are attached to

a carbonyl group O carbonyl group

CH3-C-CH3

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Naming Aldehydes

IUPAC Replace the -e in the alkane name -alCommon Add aldehyde to the prefixes form

(1C), acet (2C), propion(3), and butry(4C) O O O

H-C-H CH3-C-H CH3CH2C-H

methanal ethanal propanal(formaldehyde) (acetaldehyde) (propionaldehyde)

methaneethane propane

133

Aldehydes as Flavorings

CHO

CHO

HOOCH3

CH=CH CHO

Benzaldehyde Vanillin Cinnamaldehyde(almonds) (vanilla beans) (cinnamon)

134

Naming Ketones

In the IUPAC name, the -e in the alkane name is replaced with -one

In the common name, add the word ketone after naming the alkyl groups attached to the

carbonyl group O O

CH3 -C-CH3 CH3-C-CH2-CH3

Propanone 2-Butanone (Dimethyl ketone) (Ethyl methyl ketone)

O

Cyclohexanone

Acetone

propane butane

cyclohexane

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Preparation of aldehydes and Ketones

They are produced by oxidation of alcohols:

CH3CH2OH Oxidation

CH3CHCH3

OH

Oxidation CH3CCH3O

CH3CO

Hacetaldehyde

acetone

Primary alcohol

Secondary alcohol

ethanal

propanone

136

Question

Classify each as an aldehyde (1), ketone (2) or neither(3).

O

A. CH3CH2CCH3 B. CH3-O-CH3

CH3 O C. CH3-C-CH2CH D.

CH3

O

137

Solution

Classify each as an aldehyde (1), ketone (2) or neither(3).

O

A. CH3CH2CCH3 2 B. CH3-O-CH3 3 CH3 O

C. CH3-C-CH2CH 1 D. 2 CH3

O

138

Question

Name the followingO

A. CH3CH2CCH3 B. CH3 O C. CH3-C-CH2CH

CH3

O

139

Solution

O

A. CH3CH2CCH3 B.2-butanone (ethyl methyl ketone)

CH3 O C. CH3-C-CH2CH

cyclohexanone CH3

2,2-dimethylbutanal

O

140

Question

Draw the structural formulas for each:

A. 3-Methylpentanal

B. 2,3-Dichloropropanal

C. 3-Methyl-2-butanone

141

Solution Draw the structural formulas for each:

CH3 O A. 3-Methylpentanal CH3CH2CHCH2CH

Br O

B. 2,3-Dibromopropanal Br-CH2CHCH

O

C. 3-Methyl-2-butanone CH3CHCCH3

CH3

142

Carboxylic Acids and Esters Carboxyl Group

Carboxylic acids contain the carboxyl group as carbon 1.

O R

CH3 — C—OH : CH3—COOH

carboxyl group

143

Naming Carboxylic Acids

Formula IUPAC Common alkan -oic acid prefix – ic acid

HCOOH methanoic acid formic acid

CH3COOH ethanoic acid acetic acid

CH3CH2COOH propanoic acid propionic acid

CH3CH2CH2COOH butanoic acid butyric acid

144

Naming Rule for Carboxylic acids

• Identify longest chain• (IUPAC) Number carboxyl carbon as 1carboxyl carbon as 1 CH3

|CH3 — CH—CH2 —COOHIUPAC 3-methylbutanoic acid

1234

145

Question

Give IUPAC name:

A. CH3COOH

CH3

|

B. CH3CHCOOH

2

146

Solution

A. CH3COOH ethanoic acid; acetic acid

CH3

|

B. CH3CHCOOH 2-methylpropanoic acid;

147

Preparation of carboxylic acids

• Oxidation of primary alcohols

CH3CH2OH CH3COOHKMnO4

148

Reaction of carboxylic acid with alcohol

CH3CO

OH + H OCH2CH3

CH3CO

OCH2CH3 + H2O

Ester

Carboxylic acid Alcohol

Esterification

149

Esters

In a ester, the H in the carboxyl group is replaced with an alkyl group

O

CH3 — C—O —CH3 : CH3—COO —CH3

ester group

•Esters give fruity odors

150

Naming Esters

• The parent alcohol is named first with a –yl ending

• Change the –oic ending of the parent acid to –ate

acid alcohol O methylCH3 — C—O —CH3

Ethanoate methyl ethanoate (IUPAC)(acetate) methyl acetate (common)

151

Some esters and their names

Flavor/OdorRaspberries

HCOOCH2CH3 ethylmethanoate (IUPAC)ethylformate (common)

PineapplesCH3CH2CH2 COOCH2CH3

ethylbutanoate (IUPAC)ethylbutyrate (common)

152

QuestionGive the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears.

O CH3 — C— O —CH2CH2CH3

153

Solution

O propyl

CH3 — C—O —CH2CH2CH3

propylethanoate (IUPAC)propyl acetate (common)

154

Question

Draw the structure of the following compounds:

A. 3-bromobutanoic acid

B. Ethyl propionoate

155

Solution

A. 3-bromobutanoic acid Br |

CH3CHCH2COOH

B. Ethyl propionoate O CH3 CH2 COCH2CH3 CH3CH2COOCH2CH3

156

Hydrolysis of esters

• Esters react with water and acid catalyst• Split into carboxylic acid and alcohol

O H+

H — C—O—CH2CH3 + H2O

O

H — C—OH + HO—CH2CH3

-OHH

157

Amines• Organic compounds of nitrogen N;

derivatives of ammonia• Classified as primary, secondary, tertiary

CH3 CH3

CH3—NH2 CH3—NH CH3—N — CH3

Primary Secondary Tertiary one N-C two N-C three N-Cbond bonds bonds

158

Naming Amines

IUPAC aminoalkane Common alkylamineCH3CH2NH2 CH3—NH —CH3

aminoethane N-methylaminomethane(ethylamine) (dimethylamine)

NH2

|CH3CHCH3

2-aminopropane Aniline N-methylaniline(isopropylamine)

NH2 NH CH3

159

Question

Give the common name and classify:

A. CH3NHCH2CH3

CH3

|B. CH3CH2NCH3

160

Solution

A. CH3NHCH2CH3

ethylmethylamine, (Secondary)

CH3 |B. CH3CH2NCH3

ethyldimethylamine, (Tertiary)

161

Question

Write a structural formula for

A. 2-aminopentane

B. 1,3-diaminocyclohexane

162

Solution

A. 1-aminopentane CH3CH2CH2CH2CH2-NH2

B. 1,3-diaminocyclohexane

NH2

NH2

163

PolymersPoly= many; mers=parts

• Polymers are large, usually chainlike molecules that are built from small molecules called monomers joined by covalent bonds

Monomer PolymerEthylene PolyethyleneVinyl chloride Polyvinyl

chlorideTetrafluoroethylene Teflon

164

Some common synthetic polymers, their monomers and applications

165

Types of Polymerization

Addition Polymerization:Addition Polymerization: monomers “add together” to form the polymer, with no other products. (Teflon)

Condensation Polymerization:Condensation Polymerization: A small molecule, such as water, is formed for each extension of the polymer chain. (Nylon)

166

Addition Polymerization

OH

C CHH

HH

COH

H CH

H

H

C CHH

HH

COH

H CH

H

H

COH

H CH

H

HC CH H

H H

The polymerization processIs initiated by a free radical

A species with an unpaired electron such as hydroxyl free radical

Free radical attacks and breakThe bond of ethylene moleculeTo form a new free radical

• Repetition of the process thousands of times creates a long chain polymer• The process is terminated when two radicals react to form a bond; thus there will be no free radical is available for further repetitions.

167

Condensation PolymerizationFormation of Nylon

NH

H(CH2)6 N

H

H CO

O (CH2)4H CO

O HHexamethylendiamine Adipic acid

NH

H(CH2)6 N

HC (CH2)4 C

O

O H

O+ H2O

• Small molecule such as H2O is formed from each extension of the polymer chain• both ends are free to react

Dimer

Diamine Dicarboxylic acid

168

NH

(CH2)6 NH

( C (CH2)4 COO

)n

Nylon

169

Proteins

• Natural polymers made up of -amino acids (molecular weight from 6000 to >1,000,000 g/mol).

1. Fibrous Proteins: provide structural integrity and strength to muscle, hair and cartilage.

170

Proteins

2. Globular Proteins: Roughly spherical shape Transport and store oxygen and

nutrients Act as catalysts Fight invasion by foreign objects Participate in the body’s regulatory

system Transport electrons in metabolism

171

-Amino Acids

NH2 always attached to the -carbon (the carbon attached to COOH)

•C = -carbon

H2N C

H

COOH

R

172

Bonding in -Amino Acids

• + H2O

•

A peptide linkage (amide group)

•There are 20 amino acids commonly found in proteins.• Additional condensation reaction produces polypeptide eventually yielding a protein

CNH

H

H

R

C

O

N

H

C

H

R'

CO

OHDipeptide

• The protein polymer is built by condensation reaction between amino acids

173

The 20 Alpha-amino Acids found in most proteins

174

Levels of Structure•Primary: Sequence of amino acids in the protein chain. (lycine-alanine-leucne: (lys-ala-leu).

– So many arrangements can be predicted.

Tripeptide containing Glycine, Cysteine, and Alanine

175

Levels of Structure•Secondary: The arrangement of the protein chain in the long molecule (hydrogen bonding determines this).• Hydrogen bonding between lone pairs on an oxygen atom in the carbonyl group of an amino acid and a hydrogen atom attached to a nitrogen of another amino acid

C O NH

This type of interaction can occur with the chain coils to form a spiral structure called - helix- helix

176

Hydrogen bonding within a protein chain causes it to form a stable helical structure called the alpha-Helix

This is found infibrous protein likewool and hair givingit the elasticity

177

•Tertiary: The overall shape of the protein (determined by hydrogen-bonding, dipole-dipole interactions, ionic bonds, covalent bonds and London forces).

Summary of the Various Types of Interactions that Stabilize the Tertiary Structure of a Protein: (a) Ionic, (b) Hydrogen Bonding, (c) Covalent, (d) London Dispersion, and (e) Dipole-Dipole

178

Summary of the Various Types of Interactions that Stabilize the Tertiary Structure of a Protein: (a) Ionic, (b) Hydrogen Bonding, (c) Covalent, (d) London Dispersion, and(e) Dipole-Dipole

179

CarbohydratesCarbohydrates

Food source for most organisms and structural material for plants.Empirical formula = (CH2O)n Most carbohydrates such as starch and cellulose are polymers of monosacharides or polymers of monosacharides or simple sugar monomerssimple sugar monomersMonosaccharides (simple sugars) are polyhydroxy ketones and aldehydes

Pentoses (5-carbon atoms) - ribose, arabinoseHexoses (6-carbon atoms) - fructose, glucose

180

Some Important Monosaccharides

181

Chiral carbon atoms in fructose

• Molecules with nonsuperimposable mirror images exhibit optical isomerism

• A carbon atom with different groups bonded to it in a tetrahedral arrangement always has a nonsuperimposable mirror images which gives rise to a pair of optical isomers

182

Tetrahedral Carbon atom with four different substituents cannot have its mirror image superimposed

183

The Mirror Image Optical Isomers of Glyceraldehyde

* Chiral carbonatom

184

Fructose

D-Fructose

H2OHC

C

CHO H

C

O

H OH

C

CH2OH

OHH

**

*

There are 3 chiralCarbon atomsThere are 23 isomersThat differ in the abilityTo rotate light

185

Complex carbohydrates

Disaccharides (formed from 2 monosaccharides joined by a glycoside linkage)

sucrose (glucose + fructose)

Polysaccharides (many monosaccharide units)

starch, cellulose

186

Sucrose is a disaccharideformed from alpha-D-glucose and fructose

187

)a (The Polymer Amylose is a Major Component of Starch and is Made Up of Alpha-D-Glucose Monomers (b) The Polymer Cellulose, which Consists of Beta-D-Glucose Monomers

188

Nucleic Acids• Life is possible because each cell when it

divides can transmit the vital information about how it works to the next generation

• The substance that stores and transmits information is a polymer called deoxyribonucleic acid (DNA)

• DNA together with other similar nucleic acids called ribonucleic acids is responsible for the synthesis of various proteins needed by the cell to carry out its life functions

189

Nucleic Acids

• DNA (deoxyribonucleic acids): stores and transmits genetic information, responsible (with RNA) for protein synthesis. (Molar mass = several billion)•RNA (ribonucleic acid): helps in protein synthesis. (Molecular weight = 20,000 to 40,000)

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Monomers of nucleic acidNucleotides

1. Five-carbon sugar, deoxyribose in DNA and ribose in RNA.

2. Nitrogen containing organic base 3. Phosphoric acid molecule, H3PO4

• The base and the sugar combine to form a unit that in turn reacts with phosphoric acid to create a nucleotide• The nucleotides become connected through condensation reaction that eliminate water to give a polymer that contain a billion units.

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The Organic Bases Found in DNA and RNA

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The base and sugar combine to form a unit that in turn reacts with phosphoric acid to create the nucleotide, which is an ester

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A Portion of a typical nucleic acid chain

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Double helix formation• According to Watson and Crick (Nobel prize

winners), CAN is composed of two strands (threads) running in opposite directions that are bridged by hydrogen bonds between specific pyrimidine groups on one strand and purine group on the other

• The two strands are twisted into a double -helix structure

• The strongest hydrogen bonds form between adonine and thymine and between guanine and cystosine. Thus; A-T or G-C bonding interactions will take place

• The sequence of nucleotides on one strand of the double helix determines the sequence of the other

• The sequence of the bases determines what information is stored.

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)a (The DNA double helix contains two sugar-phosphate backbones, with the bases from the two strands hydrogen bonded to each other; the complementarity of the (b) thymine-adenine and (c) cytosine-guanine pairs

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