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The Role of Evolution and the Moleculesof Life
Evolution is the theory that all living thingsEvolution is the theory that all living things
have changed in response to environmentalhave changed in response to environmental
conditions by the natural selection of randomlyconditions by the natural selection of randomlyoccurring mutations, developing from the simplestoccurring mutations, developing from the simplest
forms to complex forms hich are more prolificforms to complex forms hich are more prolific
and stronger, due to their better adaptation toand stronger, due to their better adaptation to
their environment.their environment.
!harles "arin!harles "arin provided this insight thatprovided this insight thatestablishes a great chain connecting the distantestablishes a great chain connecting the distant
past to the present.past to the present.
#t the molecular level, evolution is the history#t the molecular level, evolution is the history
of the emergence of more complex biomoleculesof the emergence of more complex biomolecules
from simpler organic monomeric units or evenfrom simpler organic monomeric units or evenfrom inorganic counterparts.from inorganic counterparts.
http://www2.lucidcafe.com/lucidcafe/library/96feb/darwin.htmlhttp://www2.lucidcafe.com/lucidcafe/library/96feb/darwin.htmlhttp://www2.lucidcafe.com/lucidcafe/library/96feb/darwin.html
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$he ell %non$he ell %non &iller'(rey experiment &iller'(rey experiment
shoed that simple components can reactshoed that simple components can react
abiotically )or in the absence of life* to giveabiotically )or in the absence of life* to give
rise to biologically important compounds +rise to biologically important compounds +
such as components of proteins and nucleicsuch as components of proteins and nucleic
acids.acids.
par%'dischargeapparatus type used inthe &iller and (reyexperiment demonstratingthe formation of organiccompounds in abiotic,primitive atmosphericconditions. -ater isheated in a closed systemcontaining /, !/, and
/2. #n electric discharge
is passed through themixture of gasessimulating lightning. #fterseveral days, organicmolecules including aminoacids ere among theproducts collected.
click to
see bigger picture
http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/miller.htmlhttp://www.chem.duke.edu/~jds/cruise_chem/Exobiology/miller.htmlhttp://www.chem.duke.edu/~jds/cruise_chem/Exobiology/miller.html
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#fter the spontaneous synthesis of#fter the spontaneous synthesis of
organic molecules, the next step in evolutionorganic molecules, the next step in evolution
as the formation of macromolecules. (nderas the formation of macromolecules. (nder
prebiotic conditions, macromolecules areprebiotic conditions, macromolecules are
formed spontaneously from monomericformed spontaneously from monomeric
building bloc%s as shon belo.building bloc%s as shon belo.
Figure from Lehninger,
Albert et. al. 1993.
Principles of Biochemistry
2 nd ed. orth Publishers,
!e" #or$.
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rom macromolecules come supramolecularrom macromolecules come supramolecular
complexes hich no become integral partscomplexes hich no become integral parts
and components of living cells.and components of living cells.
Figure from Lehninger,
Albert et. al. 1993.
Principles of Biochemistry
2 nd ed. orth Publishers,
!e" #or$.
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3ne of the important molecules of life is3ne of the important molecules of life is
hat e %no as genes + but are actuallyhat e %no as genes + but are actually
chemically,chemically, deoxyribonucleic acids (DNA)deoxyribonucleic acids (DNA)
++ that define biological structure and maintainthat define biological structure and maintain
cellular integrity. $hese genes encodecellular integrity. $hese genes encode
proteinsproteins that ma%e up cellular structuresthat ma%e up cellular structures
and carry out many activities in the cell,and carry out many activities in the cell,
particularly catalytic activity, that increasesparticularly catalytic activity, that increases
rates of cellular reactions producing largerates of cellular reactions producing large
numbers of complex molecules. $henumbers of complex molecules. $he
4 4decoding5 or expression of coded geneticdecoding5 or expression of coded genetic
info in "# into proteins is made possible byinfo in "# into proteins is made possible by
another molecule + theanother molecule + the ribonucleic acidsribonucleic acids
(RNA)(RNA)..
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$his trio of macromolecules + "#, #$his trio of macromolecules + "#, #andand
proteins + is present in all cells. $he restproteins + is present in all cells. $he restareare
polysaccharides, ater, inorganic ions and apolysaccharides, ater, inorganic ions and a
large array of small organic molecules.large array of small organic molecules.
agvargasagvargas01.VI.200601.VI.2006
DNA
RNA
Protein
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$he central dogma of molecular biology$he central dogma of molecular biology
illustrated in the figure belo shos theillustrated in the figure belo shos the
organi7ing principle in the flo of geneticorgani7ing principle in the flo of genetic
information8 "# to # to protein.information8 "# to # to protein.
Sources of Figures:
%ampbell, &ary '. and (ha"n ). Farrell. 2**+. Biochemistry th ed. -homson
Broo$s%ole, Belmont, %A.
Lehninger, Albert et. al.1993. Principles of Biochemistry 2 nd ed. orth Publishers, !e"
#or$.
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3f the macromolecules in present'day3f the macromolecules in present'day
cells, only the nucleic acids are capable ofcells, only the nucleic acids are capable of
directing their on self'replication.directing their on self'replication.
ucleic acids can serve as templates forucleic acids can serve as templates fortheir on synthesis as a result of specifictheir on synthesis as a result of specific
base pairing beteen complementarybase pairing beteen complementary
nucleotides.nucleotides.
4 4# critical step in understanding# critical step in understanding
molecular evolution as thus reached in themolecular evolution as thus reached in the
early 19:0s, hen it as discovered in theearly 19:0s, hen it as discovered in the
laboratories oflaboratories of id #ltman id #ltman and $om !echand $om !ech
that # is capable of cataly7ing a numberthat # is capable of cataly7ing a number
of chemical reactions, including theof chemical reactions, including thepolymeri7ation of nucleotides. # is thuspolymeri7ation of nucleotides. # is thus
uni;uely able both to serve as a templateuni;uely able both to serve as a template
for and to cataly7e its on replication.for and to cataly7e its on replication.
%ampbell, &ary '. and (ha"n
). Farrell. 2**+. Biochemistry
th ed. -homson Broo$s%ole,
Belmont, %A.
http://nobelprize.org/chemistry/laureates/1989/altman-autobio.htmlhttp://nobelprize.org/chemistry/laureates/1989/altman-autobio.htmlhttp://nobelprize.org/chemistry/laureates/1989/altman-autobio.html
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!onse;uently, # is generally believed!onse;uently, # is generally believed
to have been the initial genetic system, andto have been the initial genetic system, and
an early stage of chemical evolution is thoughtan early stage of chemical evolution is thought
to have been based on self'replicating #to have been based on self'replicating #
molecules a period of evolution %non as themolecules a period of evolution %non as the
RNA worldRNA world..
3rdered interactions beteen # and3rdered interactions beteen # and
amino acids then evolved into the present'dayamino acids then evolved into the present'daygenetic code, and "# eventually replaced #genetic code, and "# eventually replaced #
as the genetic material.5 as the genetic material.5
/(ource0/(ource0 %ooper, . &. 2***. -he%ooper, . &. 2***. -he
%ell 0 A &olecular Approach. 2 %ell 0 A &olecular Approach. 2 nd nd ed.ed.
(inauer Associates, nc., (underland, &A.(inauer Associates, nc., (underland, &A.
Link to RNA-world
Hypothesis
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agvargasagvargas01.VI.200601.VI.2006Figures from %ampbell, &ary '. and (ha"n ). Farrell. 2**+.Biochemistry th ed. -homson Broo$s%ole, Belmont, %A.
The following gures show the stages in theevolution of a system of self-replicating RNAmolecules. At each stage more comple!ity appearsin the group of RNAs leading eventually to the
synthesis of proteins as more e"ective catalysts.
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bac%