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INTRODUCTION TOORGANIC COMPOUNDS
Copyright 2009 Pearson Education, Inc.
Chapter 3: The Molecules of Cells
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3.1 Lifes molecular diversity is based on the
properties of carbon
Diverse molecules found in cells are composed
of carbon bonded to oter elements
! Carbon"based molecules are called organic
compounds
! #$ sarin% electrons& carbon can bond to four oter
atoms
! #$ doin% so& it can branc in up to four directions
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3.1 Lifes molecular diversity is based on the
properties of carbon
Metane 'C()
* is one of te simplest or%anic compounds! +our covalent bonds lin, four $dro%en atoms to te carbon atom'sarin% a pair of electrons*
compounds composed of onl$ carbon and $dro%en are calledhydrocarbons
Copyright 2009 Pearson Education, Inc.
Structural
formulaBall-and-stick
model
Methane
The four single bonds of carbon point to the
Corners of a tetrahedron.
Space-fillingmodel
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Carbon skeletons vary in length.
Branching. Skeletons may be unbranched or branched.
Butane Isobutane
Propanethane
!ouble bonds.
"-Butene
Skeletons may have double bonds#$hich can vary in location.
Cyclohe%ane
&ength.
'-Butene
Ben(ene
Skeletons may be arranged in rings.)ings.
A cain of carbon
atoms is called a carbon
skeleton!Carbon s,eletons can be
brancedor unbranced
!Terefore& different
compounds -it te samemolecular formula can be
produced
!Tese structures are
called isomers
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3.2 Characteristic chemical groups help determine
the properties of organic compounds
An or%anic compound as uni.ue properties tatdepend upon
! Te si/e and sape of te molecule and! Te %roups of atoms 'functional %roups* attaced to it
A functional groupaffects a biolo%ical molecule0sfunction in a caracteristic -a$
Compounds containin% functional %roups are hydrophilic'-ater"lovin%*
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!Hydroxylgroup1 a $dro%enbonded to an o2$%en
!Carbonylgroup1 a carbonlin,ed b$ a double bond to ano2$%en atom
!Carboxylgroup1 a carbon
double"bonded to bot an o2$%enand a $dro2$l %roup
!Aminogroup1 a nitro%enbonded to t-o $dro%en atoms
and te carbon s,eleton!Phosphategroup1 a posporusatom bonded to four o2$%en atoms
!Methyl group1 a carbon bonded
to tree $dro%ens
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stradiol
Male lionTestosterone
*emale lion
Similar compounds
differ onl$ in functional
%roups3 se2 permones
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3.3 Cells make a huge number of large molecules
from a small set of small moleculesTere are four classes of biolo%ical molecules
! Carbo$drates
! Proteins
! 4ipids
!Nucleic acids
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!Te$ are often calledmacromoleculesbecause of teir
lar%e si/e
!Te$ are also called polymersbecause te$ are madefrom identical buildin% bloc,s
!Te buildin% bloc,s are called monomers
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3.3 Cells make a huge number of large molecules
from a small set of small molecules
Monomers are lin,ed to%eter to form pol$mers
trou% dehydration reactions& -ic remove
-ater
Pol$mers are bro,en apart b$ hydrolysis& te
addition of -ater
All biolo%ical reactions of tis sort are mediated b$
enzymes& -ic speed up cemical reactions in cells
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+nlinkedmonomer
Short polymer
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+nlinkedmonomer
Short polymer
&onger polymer
!ehydrationreaction
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,ydrolysis
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CARBOHYDRATES
Carbo$drates ran%e from small su%armolecules'monomers* to lar%e pol$saccarides! Su%ar monomers are monosaccharides& suc as
%lucose and fructose
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3 4 h id h i l
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3.4 Monosaccharides are the simplest
carbohydrates
Te carbon s,eletonsof monosaccaridesvar$ in len%t! Glucose and fructose
are si2 carbons lon%! Oters ave tree to
seven carbon atoms
Monosaccharidesare the main fuelsfor cellular ork
Copyright 2009 Pearson Education, Inc.
lucose
an aldose/*ructose
a ketose/
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Structuralformula
0bbreviatedstructure
Simplifiedstructure
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lucose lucose
Maltose
T-o mono"
saccarides
'monomers*can bond to
form a
disaccharidein a
de$dration
reaction
lucose 1 *ructose2
Sucrose
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!tarchis a stora%e pol$saccaride composed of
%lucose monomers and found in plants
"lycogenis a stora%e pol$saccaride composed
of %lucose& -ic is $drol$/ed b$ animals-en %lucose is needed
Celluloseis a pol$mer of %lucose tat forms
plant cell -alls
Chitinis a pol$saccaride used b$ insects and
crustaceans to build an e2os,eleton
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olysaccharides are polymers of
monosaccharides
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Starch granules inpotato tuber cells
lycogengranules
in muscletissue
Cellulose fibrils ina plant cell $all
Cellulosemolecules
lucosemonomer
&3C45
C&&+&4S
,ydrogen bonds
ST0)C,
Pol$saccarides are $dropilic'-ater"lovin%*!Cotton fibers& suc as tose in bat to-els& are -ater absorbent
3 ! " t li id th t tl
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3.! "ats are lipids that are mostly energy#
storage molecules
#ipidsare -ater insoluble 'hydrophobic& or -aterfearin%* compounds tat are important in ener%$
stora%e
! Te$ contain t-ice as muc ener%$ as a pol$saccaride
$atsare lipids made from %l$cerol and fatt$ acids
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3.! "ats are lipids that are mostly energy#
storage molecules
+att$ acids lin, to %l$cerolb$ a de$drationreaction
! A fat contains one %l$cerol
lin,ed to tree fatt$ acids! +ats are often called
tri%l$ceridesbecause of
teir structure
Copyright 2009 Pearson Education, Inc.
*atty acid
lycerol
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3.! "ats are lipids that are mostly energy#
storage molecules
Some fatt$ acids contain double bonds! Tis causes bends in te carbon cain
! Tese compounds are called unsaturatedfats!because te$ ave fe-er tan te ma2imum number of
$dro%ens
!+ats -it te ma2imum number of $dro%ens are calledsaturated fats
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3.$ hospholipids and steroids are important
lipids %ith a variety of functionsPhospholipidsare structurall$ similar to fats and are an
important component of all cells! +or e2ample& te$ are a ma5or part of cell membranes
! Te $dropilic eads are in contact -it te -ater of te environment
and te internal part of te cell
! Te $dropobic tails band in te center of te bila$er
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6ater
,ydrophobictails
,ydrophilicheads
6ater
3 $ h h li id d t id i t t
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3.$ hospholipids and steroids are important
lipids %ith a variety of functions
!teroidsare lipids composed of fused rin%structures
! Cholesterolis an e2ample of a steroid tat pla$s a
si%nificant role in te structure of te cell membrane
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3.1& C'(()C*+'(,-nabolic steroids
pose health risks
Anabolic steroidsare s$ntetic variants oftestosterone tat can cause a buildup of muscleand bone mass! Te$ can be sold as prescription dru%s and used to
treat certain diseases 'anemia& bod$ muscle*! Te$ ma$ also be abused -it serious conse.uences&
suc as liver dama%e tat can lead to cancer
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3.11 '*)+(/ are essential to the structures
and functions of life
A proteinis a pol$mer built from various
combinations of 67 amino acid monomers
! Proteins ave uni.ue structures tat are directl$
related to teir functions
! %nzymes& proteins tat serve as metabolic catal$sts&
re%ulate te cemical reactions -itin cells
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3.11 roteins are essential to the structures
and functions of life
!tructuralproteins provide associationsbet-een bod$ parts and contractileproteins arefound -itin muscle
&efensi'eproteins include antibodies of teimmune s$stem& and signalproteins are beste2emplified b$ te ormones
(eceptorproteins serve as antenna for outsidesi%nals& and transportproteins carr$ o2$%en
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3.12 roteins are made from amino acids
linked by peptide bonds
Amino acids& te buildin% bloc,s of proteins& ave anamino %roup and a carbo2$l %roup
! #ot of tese are covalentl$ bonded to a central carbon atom
! Also bonded to te central carbon is a $dro%en atom and
some oter cemical %roup s$mboli/ed b$ R
Copyright 2009 Pearson Education, Inc.
Carbo%ylgroup
0minogroup
0mino acids are
classified as
hydrophobic orhydrophilic
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&eucine &eu/
,ydrophobic
Serine Ser/
,ydrophilic
0spartic acid 0sp/
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Carbo%ylgroup
0mino acid
0minogroup
0mino acid
Peptidebond
!ipeptide
!ehydrationreaction
0mino acid monomers are linked together to
form polymeric proteins
The covalent linkage resulting is called apeptide bond
0 polypeptide chain contains hundreds or
thousands of amino acids linked by peptide bonds
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roove
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roove
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3.13 - proteins specific shape determines
its function
If for some reason a protein0s sape is altered& itcan no lon%er function
! &enaturation-ill cause pol$peptide cains to
unravel and lose teir sape and& tus& teir function!Proteins can be denatured by changes in saltconcentration and pH
Copyright 2009 Pearson Education, Inc.
0 protein can have four levels
of structurePrimary structureSecondary structureTertiary structure
7uaternary structure
*our &evels of Protein Structure
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*our &evels of Protein Structure
0mino acids
Primary structure
*our &evels of Protein Structure
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*our &evels of Protein Structure
0mino acids
Primary structure
0lpha heli%
,ydrogenbond
Secondary structure
Pleated sheet
*our &evels of Protein Structure
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*our &evels of Protein Structure
0mino acids
Primary structure
0lpha heli%
,ydrogenbond
Secondary structure
Pleated sheet
Polypeptidesingle subunit
of transthyretin/
Tertiary structure
4verall 8-!
structure
*our &evels of Protein Structure
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*our &evels of Protein Structure
0mino acids
Primary structure
0lpha heli%
,ydrogenbond
Secondary structure
Pleated sheet
Polypeptidesingle subunit
of transthyretin/
Tertiary structure
Transthyretin# $ithfour identicalpolypeptide subunits
7uaternary structure
T$o or more
polypeptides
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3.10 (ucleic acids are information#rich
polymers of nucleotides
&)A'deoxyribonucleic acid* and ()A'ribonucleic acid* are composed of monomers
called nucleotides
!Nucleotides ave tree parts!A five"carbon su%ar called ribose in RNA and deo2$ribose
in DNA
!A pospate %roup
!A nitro%enous base
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5itrogenousbase
adenine/
Sugar
Phosphategroup
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Sugar-phosphate
backbone
5ucleotide
0 nucleic acid polymer# apolynucleotide# forms from
the nucleotide monomers$hen the phosphate of one
nucleotide bonds to the sugarof the ne%t nucleotide
!50 nitrogenous bases areadenine 0/# thymine T/#
cytosine C/# and guanine /)50 also has 0# C# and #
but instead of T# it hasuracil +/
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Basepair
T$o polynucleotide strands
form a !50 double heli%The t$o strands are
associated because
particular bases al$ays
hydrogen bond to one
another0 pairs $ith T# and C
pairs $ith # producing
base pairs
)50 is usually a singlepolynucleotide strand
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3.10 (ucleic acids are information#rich
polymers of nucleotides
A particular nucleotide se.uence tat can instruct te
formation of a pol$peptide is called a gene
! Most DNA molecules consist of millions of base pairs and&
conse.uentl$& many genes! Tese %enes& man$ of -ic are uni.ue to te species&
determine te structure of proteins and& tus& life0s structures
and functions
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You should now be able to
89 Discuss te importance of carbon to lifesmolecular diversit$
69 Describe te cemical %roups tat areimportant to life
:9 ;2plain o- a cell can ma,e a variet$ of lar%emolecules from a small set of molecules
)9 Define monosaccarides& disaccarides& andpol$saccarides and e2plain teir functions
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You should now be able to
=9 Describe te cemical structure of proteins andteir importance to cells
>9 Describe te cemical structure of nucleic acidsand o- te$ relate to ineritance