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Paul D. Adams • University of Arkansas

Mary K. Campbell

Shawn O. Farrellhttp://academic.cengage.com/chemistry/campbell

Chapter One

 Biochemistry and the Organization of Cells

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Some Basic Themes

•  All liing things ma!e "se of the same types of biomolec"les#

and all "se energy• as a res"lt# all liing things can be st"died "sing the

methods of chemistry and physics

• The f"ndamental similarity of cells of all types ma!es itinteresting to spec"late on the origins of life

• both cells and the biomolec"les of which they are madem"st hae arisen "ltimately from ery simple molec"les#

s"ch as $%O# C$&# CO%# '$(# '%# and $%

) Field of Biochemistry draws many disciplines

) allows "s to answer *"estions related to molec"lar nat"re

of life

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Biomolec"les

• Organic chemistry:Organic chemistry: the st"dy of the compo"nds of

carbon

• the cell"lar apparat"s of liing organisms is made "p

of carbon compo"nds

•

biomolec"les are part of the s"b+ect matter of organicchemistry

• the reactions of biomolec"les can be described by the

methods of organic chemistry

• The e,periment of Friedrich -hler in /0%0

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1eels of Str"ct"ralOrganization in the$"man Body

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Biomolec"les 2Cont3d4

• Functional group:Functional group: an atom or gro"p of atoms that shows

characteristic physical and chemical properties

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 AT5 and The 6eactions for its Formation

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Origins of 1ife

• The 7big bang8 theory• all matter was originally confined in a ery small space

• as the res"lt of an e,plosion# it started to e,pand with greatforce9 temperat"re appro,. /: , /;<K

• the aerage temperat"re of the "nierse has been decreasingeer since

• in the earliest stages of the "nierse# the only elements presentwere $# $e# and 1i

• other elements formed by

•thermonuclear reactions in stars

•explosions of stars•the action of cosmic rays outside the stars

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6elatie Ab"ndance of =mportant >lements

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Biomolec"les 2Cont3d4

• ?ases present in the atmosphere of the early earth incl"ded

'$(# $%S# CO# CO%# C$&# '%# $%# and $%O b"t not O%

• >,periments hae demonstrated that important biomolec"les#s"ch as proteins and n"cleic acids# co"ld hae arisen "nder

abiotic 2nonliing4 conditions from reactions of these simplecompo"nds• in the earth3s oceans

• on the s"rface of clay particles

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Biomolec"les 2Cont3d4

• 1iing cells incl"de ery large molec"les# s"ch as proteins#

n"cleic acids# polysaccharides# and lipids• these biomolec"les are polymers

 2?ree!@ poly   meros# many parts4

•

they are deried from monomers2?ree!@ mono  meros# single part4

  amino acids  proteins

  n"cleotides  n"cleic acids

  monosaccharides  polysaccharides

  glycerol and ( fatty acids  lipids

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=nformational Macromolec"les

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Biomolec"les 2Cont3d4

• Enzymes:Enzymes: a class of proteins that are biocatalysts

• the catalytic effectieness of a gien enzyme depends on its

amino acid se*"ence

• Genetic code:Genetic code: the relationship between the n"cleotide

se*"ence in n"cleic acids and the amino acid se*"ence in

proteins• theories of the origin of life consider how s"ch a coding system

might hae arisen

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Biomolec"les 2Cont3d4

• -hich came firstthe chic!en or the egg

•catalytic activity associated with proteins

•coding associated with nucleic acids

• It has been discovered recently that certain types of RNA have

catalytic activity and are capable of catalyzing their own furtherprocessing (See Figure 1.7 p.12)

•RNA is now considered by many scientists to have beenthe original coding material

•it still serves this function in some viruses

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The 76'A -orld8

• The appearance of a form of 6'A capable of coding

for its own replication was the piotal point in the originof life

•

This original 6'A both encoded for and catalyzed itsown replication

• =n time# this system eoled to encode for the

synthesis of protein catalysts

• >en later# D'A became the primary genetic material#and 6'A too! on only an intermediary role in the

synthesis of proteins

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Stages in the >ol"tion of SelfEreplicating 6'A Molec"les

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Theories on the Origin of 1ife

•  A !ey point in the deelopment of liing cells is the

formation of membranes that separate cells from theirenironment

• Some theories of the origin of life foc"s on proteins

•

according to one model# proteinoids aggregated toform microspheres

• Double-Origin theory:Double-Origin theory: the deelopment of a coding

system and the deelopment of catalysis came abo"t

separately• a combination of the two later in time prod"ced life as

we !now it.

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Comparison of 5ro!aryotes and >"!aryotes

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• Important organelles

listed in table 1.3

 A Comparison of a typical animal cell# plant cell# and pro!aryotic

cell

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Comparison of 5ro!aryotes and >"!aryotes

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Fie Kingdoms# Three Domains

• :E!ingdom system ta!es into acco"nt differences

between pro!aryotes and e"!aryotes

• 5roides classification for e"!aryotes that are neither

plants nor animals

• Kingdoms are@ Monera# 5rotista# F"ngi# 5lantae# and Anamilia

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Fie Kingdoms# Three Domains

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-hat is so"rce of energy in cells

) 1ight from the s"n is the "ltimate so"rce of energy for

all life on earth• photosynthetic organisms "se light energy to drie the

energyEre*"iring synthesis of carbohydrates

• nonEphotosynthetic organisms cons"me these

carbohydrates and "se them as energy so"rces

• The energetics of a chemical reaction

•if the change in free energy is negative (free energy

decreases), the reaction is spontaneous as written•if the change in positive (free energy increases), thereaction will not occur as written unless energy is

supplied from an external source 

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How are energy changes measured?

Thermodynamics- branch of science that answers questions

about processes that are energetically favorable

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Spontaneity in biochemical reactions

• Free Energy of a System

  ∆G < 0 spontaneous exergonic- energy released

  ∆G= 0 Equilibrium

  ∆G > 0 Nonspontaneous endergonic- energy required

• Life and Thermodynamics   ∆G=∆H-T∆S

  ∆H is heat of a reaction at constant pressure

  ∆

S is the change in entropy   ∆G is the change in free energy

•T is the temperature