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Hitos de la vida II En la tierra: protobiontes y desde las
primeras células a los organismos
pluricelulares
Autocatálisis en micelas
Master Geologia P&DB 60433 Hitos vida tierra II 5
NATURE
COMMUNICATIONS
Physical autocatalysis driven
by a bond-forming thiol–ene
reaction
Andrew J. Bissette,
Barbara Odell
& Stephen P. Fletcher
Affiliations
Contributions
Corresponding author
Nature
Communications 5, Article
number: 4607 doi:10.1038/nc
omms5607Received 22
March 2014 Accepted 07
July 2014 Published 02
September 2014
Procesos necesarios para la abiogénesis en la Tierra
Finalmente, se produce el
empaquetamiento de las moléculas
en membranas, con una química
interna diferente de la de los
alrededores.
La formación de membranas
cerradas es un paso importante. Como hemos visto las vesículas o
micelas de membranas cerrada se
forman expontáneamente por lo lípidos.
Esto permite la diferenciación entre un
medio interno y otro interno.
http://e
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La formación de protocélulas
Master Geologia P&DB 60433 Hitos vida tierra II 7
Ricard V Solé et al. Phil. Trans. R. Soc. B 2007;362:1727-1739.
©2007 by The Royal Society
No-replicante Replicante sin evol. Cel. evoluciona
Acell: célula artificial
La formación de protocélulas
Master Geologia P&DB 60433 Hitos vida tierra II 8
Ricard V Solé et al. Phil. Trans. R. Soc. B 2007;362:1727-1739.
©2007 by The Royal Society
Von Neumann (1966) y la
máquina autoreplicante.
La lógica de la máquina de
Neumann: parecida a la de las
células vivas.
¿Estamos ya en presencia de los Protobiontes?
Master Geologia P&DB 60433 Hitos vida tierra II 9 protobiontes
Moléculas autoreplicantes
O En la célula actual el DNA se puede replicar, pero necesita la ayuda de las enzimas (proteinas) para lograrlo.
Master Geologia P&DB 60433 Hitos vida tierra II 10
Moléculas autoreplicantes O En la célula actual el DNA se puede replicar, pero necesita la ayuda de las enzimas (proteinas) para lograrlo.
O Las proteinas se ensamblan sobre la base
de información del ADN, que transcribe el
ARN.
O pero..... ¿qué fué primero?
O el DNA para hacer proteinas?
O o las proteins para hacer DNA?!?!?!?!?
Master Geologia P&DB 60433 Hitos vida tierra II 11
Moléculas autoreplicantes
O La síntesis de DNA y RNA requiere
proteinas.
O Por tanto
O Las proteinas no pueden sintetizarse sin
acidos nucleicos y …
O Los acidos nucleicos no sin proteinas
O !Falso!
Master Geologia P&DB 60433 Hitos vida tierra II 12
Moléculas autoreplicantes
O Hemos visto la síntesis de nucleótidos y sus bases se polimerizan para formar ácido ribonucleico (RNA).
Master Geologia P&DB 60433 Hitos vida tierra II 13
Moléculas autoreplicantes O Hemos visto la síntesis de nucleótidos y sus bases se
polimerizan para formar ácido ribonucleico (RNA).
O Así puede formarse
una hebra de RNA
Master Geologia P&DB 60433 Hitos vida tierra II 14
Nucleótidos del ARN: Adenina, Guanina, Citosina y Uracilo
Moléculas autoreplicantes
O La hebra de RNA
Master Geologia P&DB 60433 Hitos vida tierra II 15
Procesos necesarios para la abiogénesis en la Tierra
El origen de las moléculas autoreplicantes
permite la herencia.
• El ADN (DNA) no puede
autoreplicarse, necesita enzimas
proteicas.
• Sin embargo, algunos ARN puede
auto-replicarse, pueden catalizar la
formación de copias de sí mismo.
• Se llaman ribozimas y son la base de
la RNA World Hypothesis
Origen y evidencia experimental
moléculas fósiles en el tiempo geológico I
Master Geologia P&DB 60433 Hitos vida tierra II
19
moléculas fósiles en el tiempo geológico
II
Master Geologia P&DB 60433 Hitos vida tierra II
20
Fungi
EUKARYA
Trypanosomes
Green algae Land plants
Red algae
Forams Ciliates
Dinoflagellates
Diatoms
Animals
Amoebas Cellular slime molds
Leishmania
Euglena
Green nonsulfur bacteria
Thermophiles
Halophiles
Methanobacterium
Sulfolobus
ARCHAEA
COMMON ANCESTOR
OF ALL LIFE
BACTERIA
(Plastids, including chloroplasts)
Green sulfur bacteria
(Mitochondrion)
Cyanobacteria
Chlamydia
Spirochetes
Tree of life
Master Geologia P&DB 60433 Hitos vida tierra II 21
Fig. 26-23
Archaea Bacteria
Eukarya
The End
Ring of life
Master Geologia P&DB 60433 Hitos vida tierra II 22
Un origen común
Master Geologia P&DB 60433 Hitos vida tierra II 23
Origen de las células
La idea esencial es que hay una
cadena contínua desde las primeras
células a los organismos actuales.
Células fósiles del Precámbrico.
Presentan los mismos principios
básicos
http://rstb.royalsocietypublishing.org/content/361/1470/1023/F3.large.jpg
Chris Paine
https://bioknowledgy.weebly.com/
Las células sólo se pueden formar por la división de células anteriores.
Estructuras complejas que no se han podido “formar” en el laboratorio de unidades más simples.
http://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Eukaryotic_Cell_%28animal%29.jpg/1024px-Eukaryotic_Cell_%28animal%29.jpg
http://upload.wikimedia.org/wikipedia/commons/3/3a/Influenza_virus_particle_color.jpg
Los virus se forman a partir de subunidades simples, pero no son
células y sólo se pueden reproducir
dentro de las células huésped que han
infectado.
Endosimbiosis
29
The origin of eukaryotic cells can be explained by the endosymbiotic theory.
Development of the Nucleus
• A prokaryote grows in size and develops folds in it’s membrane to
maintain an efficient SA:Vol
• The infoldings are pinched off forming an internal membrane
• The nucleoid region is enclosed in the internal membrane and hence
becomes the nucelus
http://ib.bioninja.com.au/options/option-d-evolution-2/d1-origins-of-life-on-earth.html
The origin of eukaryotic cells can be explained by the endosymbiotic theory.
http://ib.bioninja.com.au/options/option-d-evolution-2/d1-origins-of-life-on-earth.html
* An endosymbiont
is a cell which
lives inside
another cell with
mutual benefit
Development of Mitochondria
• An aerobic proteobacterium enters a larger anaerobic prokaryote (possibly as prey
or a parasite)
• It survives digestion to become a valuable endosymbiont*
• The aerobic proteobacterium provides a rich source of ATP to it’s host enabling it
to out-compete other anaerobic prokaryotes
• As the host cell grows and divides so does the aerobic proteobacterium therefore
subsequent generations automatically contain aerobic proteobacterium.
• The aerobic proteobacterium evolves and is assimilated and to become a
mitochondrion.
The development of chloroplasts would be
a very similar process except the benefit to
the cell would be glucose/starch instead of
ATP
1.5.U3 The origin of eukaryotic cells can be explained by the endosymbiotic theory.
The evidence supporting the
endosymbiotic theory for
mitochondria and chloroplasts:
• They have their own DNA (which is naked
and circular)
• They have ribosomes that are similar to
prokaryotes (70S)
• They have a double membrane and the
inner membrane has proteins similar to
prokaryotes
• They are roughly the same size as bacteria
and are susceptible to the antibiotic
chloramphenicol
• They transcribe their DNA and use the
mRNA to synthesize some of their own
proteins.
• They can only be produced by division of
pre-existing mitochondria and chloroplasts. http://sites.roosevelt.edu/mbryson/files/2011/11/endosymbiosis.jpg
Metabolismo de la vida primitiva
Master Geologia P&DB 60433 Hitos vida tierra II
33 En web de David Castro: Goldman, Aaron David, Baross, John, &
Samudrala, Ram (2012). The Enzymatic and Metabolic
Capabilities of Early Life PLOS
ONE DOI: 10.1371/journal.pone.0039912
Catálisis
O Acelerar las reacciones químicas
utilizando catalizadores
O Homogénea, heterogénea
O Catalizadores biológicos llamados:
O Enzimas
O Las enzimas, al contrario que los
catalizadores químicos, son muy
específicas.
Master Geologia P&DB 60433 Hitos vida tierra II 34
Principales eventos en la historia de la vida en la tierra O Life arose from nonlife about 4 billion years ago by means
of chemical evolution. Review Figure 1.3
O Biological evolution began about 3.8 billion years ago when interacting systems of molecules became enclosed in membranes to form cells.
O Photosynthetic prokaryotes released large amounts of oxygen into Earth's atmosphere, making aerobic metabolism possible.
O Complex eukaryotic cells evolved by incorporation of smaller cells that survived being ingested.
O Multicellular organisms appeared when cells evolved the ability to transform themselves and to stick together and communicate after they divided. The individual cells of multicellular organisms became modified to carry out varied functions within the organism.
O The evolution of sex sped up rates of biological evolution.
Master Geologia P&DB 60433 Hitos vida tierra II 35
Master Geologia P&DB 60433 Hitos vida tierra II 36
BIG BANG
Cosmic dust and gases+ H2O
Oceans
Haldane soup
Reducing atmosphere(gases like
CH4,NH3,N2,CO2,H2O responsible for
abiotic synthesis of organic compounds) Master Geologia P&DB 60433 Hitos vida tierra II 37
OPARIN-HALDANE THEORY Haldane Soup
Simple
Molecules
Complex Molecules (building
blocks)
Aggregates (coacervates and
microspheres)
Protocells( proprimitive stage before formation of true
cell
Proto cells + nucleic acid = self replicating
system
“CELL”
Microsphere
Master Geologia P&DB 60433 Hitos vida tierra II 38
ENERGY YIELDING SYSTEM
O “Cell” Energy Yielding System
• Chlorophyll development Photosynthesis
O2 evolved
Ozone Formation (shielding effect)
• Atmosphere changed to oxidizing from reducing.
• Evolution of photosynthesis which is followed by
respiration. Master Geologia P&DB 60433 Hitos vida tierra II 39
CELL
Replication Metabolism Homeostasis
Anaerobes Aerobes
Chemotrophs Heterotrophs
Chemoheterotrophs Chemoautotrophs
Prokaryotic Cells Eukaryotic cell Endosymbiotic Theory Master Geologia P&DB 60433 Hitos vida tierra II 40
How Eukaryotic Cell Changed to
Multicellular Organism….
Master Geologia P&DB 60433 Hitos vida tierra II 41
Photograph from National Geographic magazine
Master Geologia P&DB 60433 Hitos vida tierra II 42
Deep-sea Vents
O Their discovery in late 1970’s stretched our
concept of the origin of life on earth.
O Can life exist and that too thousands of
meters beneath the surface of sea in absence
of sunlight?
O It raised the possibility that earlier vents
supplied the energy and chemical
precursors for origin of protobionts.
Master Geologia P&DB 60433 Hitos vida tierra II 43
Exploring the deep ocean floor
View of the first high-
temperature vent
(380°C) ever seen by
scientists during a dive
of the deep-sea
submersible Alvin in
1979.
Such geothermal vents
are called smokers. This photograph shows a black smoker, but
smokers can also be white, grey, or clear
depending on the material being ejected.
Photograph by Dudley Foster from RISE
expedition
Master Geologia P&DB 60433 Hitos vida tierra II 44
Vent Community
A vent community in its prime: Pale pink eelpout fish and white
brachyuran crabs swim and scuttle among blood-red tube worms
large and small. Scientists are still trying to figure out how the
offspring of such organisms disperse over long stretches of
inhospitable seafloor to colonize widely separated vent systems.
Master Geologia P&DB 60433 Hitos vida tierra II 45
Giant Clams
The size of deep-sea giant clams is evident from the
hands of a scientist holding them.
(Photograph by William R. Normark, USGS.)
Master Geologia P&DB 60433 Hitos vida tierra II 46
Giant Tube Worms: RIFTIA
O On the bottom of the
ocean around deep-
sea hydrothermal
vents, there is a
profusion of life that
thrives on the
hydrogen sulfide
(H2S) gas released
from the vents.and
live inside hard,
shell-like protective
tubes that attach to
the rocks.
Giant tubeworms that live around hydrothermal vents
on the sea floor. These creatures are about the size of
your hand in shallower waters, but in the ocean's deep
they have been found as big as eight feet long!
Master Geologia P&DB 60433 Hitos vida tierra II 47
Biomoléculas
Master Geologia P&DB 60433 Hitos vida tierra II 48