A tárgy természete...
• A biológiai tudományok egysége
• Molekuláris, organizmikus és populációs
megközelítés
• Érdekes de NEHÉZ
• Aki nem akar figyelni, az menjen ki!
• Vizsga: írásban. Utóvizsga: szóban
• Vizsganyag: az előadások (órai jegyzet és
diasorozat, cikkgyűjtenény)
Az élet kettős természete
Eörs Szathmáry
Collegium Budapest
Eötvös University
Miért kettős?
• Homeosztázis—disszipatív—anyagcsere
• Egyirányú vezérlés és öröklődés
• A láng és az öröklődő tulajdonságokkal
rendelkező sejt különbözősége
Great thinkers on the nature of life
Gottfried
Leibniz
John
Maynard
Smith
Erwin
Schrödinger
Freeman
Dyson
Leibniz
• Az „isteni gépek
végtelenül oszthatónak
tűnnek
• A gépszerű működés a
„molekuláris”
dimenzióban is
érvényesül
Schrödinger
• A gén mint
aperiodikus kristály
• Az entrópia alacsony
szintjének fenntartása
állandó munkavégzést
igényel
Maynard Smith
• Anyagcsere és
homeosztázis
• Genetikai szabályozás
• Az evolvabilitást az
utóbbi adja
Freeman Dyson
• Az élet kettős eredete
• Először az anyagcsere
és a homeosztázis,
nukleinsvak nélkül
• A gének mint a
rendszer parazitái
jelenhettek meg
An irreversible system
• AB
A reversible reaction
• A  B
• Le Chatelier-Braun principle
A reversible, closed reaction
system
Reaction systems
• A closed,
reversible
cycle
• An open,
almost
reversible
system
Closed and open systems
Alul: a stacionárius állapot (steady state)
The skeleton of sugar
decomposition
Chemical cycles are metabolic
engines
• The cycle as a whole is a
catalyst
• The Noble prize of SzentGyörgyi was awarded for
catalysis by fumaric acid
• Krebs has recognized the
whole cycle
• Enzymes are superimposed
on the metabolic cycle
A simple chemical cycle
• It is formally a unit composed of a closed
and an open part
• Acts as a catalys
Engines operate in cycles, and
are hence are dynamically stable
Tibor Gánti
• Born in 1933
• Chemical engineer
• Patents in industrial
biochemistry (artificial
metabolism)
• Syntheses using the
controlled operation of
enzymatic reaction
networks
• First book on molecular
biology in Hungary (1966)
The first edition of the Principles
• A serious book in a
popular science
disguise (1971)
• There was no other
way to publish
• Proposal included the
term “chemoton”
• ‘reductionist’ and
‘vitalist’ at the same
time!
The investigation of life criteria:
absolute criteria
1.
2.
3.
4.
5.
Inherent unity
Metabolism
Inherent stability
Information carrying subsystem
Processes regulated and controlled by a
programme
VERBAL AND PHENOMENOLOGICAL
Quest for a biological minimal
system
• Chemical supersystem
• Should be conceptually as simple as
possible
• Must not necessarily be realizable in its
simplest form
• Comparison with other elementary units
(such as the elementary cell in
crystallography)
• FORMAL AND EXACT
The latest edition: OUP 2003
• After several editions
in Hungarian
• Two previous books
(the Principles and
Contra Crick) plus
one essay
• Essays appreciating
the biological and
philosophical
importance
Enzymes and cycle stoichiometry
Very
important:
the cyclic
process sign
with the
number of
turns
Structures built of amphipathic
molecules
A two-dimensional fluid
A self-reproducing vesicle (1978)
• Metabolism and reproduction
• No genetic subsystem
Pathways of supersystem evolution
metabolism
MB
boundary
MT
template
BT
MBT
INFRABIOLOGICAL SYSTEMS
Organisation of chemical systems
into a supersystem (1974)
• CHEMOTON: a particular supersystem which is
also a biological minimal system
Gánti’s chemoton model
metabolism
template
copying
membrane
growth
ALL THREE SUBSYSTEMS ARE AUTOCATALYTIC
The assembly of RNA structures
• Combinatorial
assembly of RNA
structures
• Submitted to selection
for function between
chemotons
• 1979
The channelled assembly of
ribozymes (1983)
• The presence of
substrates gives
guidance to ribozyme
assembly
• Good enzymes and
bad enzymes will
affect the fitness of the
chemotons
Venter: professional but trivial
(synthetic biology)
The monograph (Kluwer 2003)
The chemoton symbol
Evolution towards a Borromean
arrangement?
Chemoton symbol
Borromean rings