Bio für Geos Vom Molekül zum Mensch - The Cambrian explosion
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Bio für Geos
Vom Molekül zum Mensch
The Cambrian explosion
K. R. Johnson and R. K. Stucky: Prehistoric Journey: A history of life on Earth. ISBN
1-57098-145-4.
Major transitions
History of life
Major transitions in evolution
Replicating molecules Populations of molecules in
compartments
Independent replicators Chromosomes
RNA as gene and enzyme DNA + protein (genetic code)
Prokaryotes Eukaryotes
Asexual clones Sexual populations
Protists Animals, plants, fungi (cell differentiation)
Solitary individuals Colonies (non-reproductive castes)
Primate societies Human societies (language)
Common feature to many transitions:
Independent replication replication as part of a larger whole
Definition des Lebens • Problematisch: • Eigenschaften des heutigen Lebens – ..... • oder Entstehung des Lebens......
Ursprung des Lebens: Hypothesen
5
Hypothesen:
Panspermie
Leben hat irgendwo anders als auf Erde angefangen..........(verlegt das Problem nach anderen Ort)
Mikrobentransport durch Meteoriten
z.B. Meteoriten aus Gesteine von Mars sind auf Erde gefunden worden.
6
http://www.livescience.com/13363-7-theories-origin-life.html
Generatio spontanea • Aristoteles – Entstehung des Lebens immer und überall • ab 17. Jahrhundert: – Entdeckung Mikroben – 1668 Francesco Redi: Experimente mit Fleisch und Fliegen. – 1864 Louis Pasteur. • Damit entsteht die Frage wie das Leben entstanden ist • http://en.wikipedia.org/wiki/Abiogenesis 7
Entstehung des Lebens
• Darwin 1871:
– in a "warm little pond, with all sorts of ammonia and phosphoric
salts, lights, heat, electricity, etc. present, so that a protein
compound was chemically formed ready to undergo still more
complex changes".
• 1924 Alexander Oparin
– frühe Erde war anders
– “primeval soup” in anoxia mit Sonnenlicht
8
Wann und Wie
• 3.9-4.2 Ga, nach Meteoritenregen
• 1. Monomere
• 2. Polymere
• 3. Evolution Polymere zu Zellen
9
Hypothesen:
Electric spark
Genese Bauelemente für leben (Aminosäure, Zucker, Nukleotiden), aus Wasser, Methan, Ammoniak
und Wasserstoff.................und Schwefel (Parker et al., 2011 orig. Life Evol. Biosph. 2011:201-212)
Urey-Miller experiment 1953 und spätere experimente
Uratmosphäre war aber arm an Wasserstoff......
10
http://www.livescience.com/13363-7-theories-origin-life.html1: Organic molecule synthesis Life metabolites: amino acids, nucleic acids.. • Urey - Miller (1953) – primordial earth • Interstellar space – meteorites
Ursuppe
• reduzierende Atmosphäre
• + Energie führt zu Monomere
• Monomere konzentrieren sich in bestimmten
Stellen (z.B. Küsten, Vents..)
• dort bilden sich Polymere
• weitere Entwicklung des Lebens in Ursuppe
122: Monomers to polymers • Probleme mit Ursuppe: – Diffusion der Monomere – Stabilität der Polymere • Minerale als Katalysatoren (prebiotische Pizza).
Hypothesen:
Community clay:
Alexander Graham Cairns-Smith (University of Glasgow, Scotland)
Tonmineralien führen zur:
- Konzentation organische komponente
- Organisation der Organische Komponente
Hauptrolle DNA: Informationsspeicher - wie Aminosäuren zu
Proteine zu verketten. Tonmineralien könnten am Anfang die
organische Moleküle in Muster organisiert haben; später ist dann
diese Rolle von organische Moleküle übernommen worden
14
http://www.livescience.com/13363-7-theories-origin-life.htmlHypothesen:
Deep Sea Vents
Vents sind teilweise reich an Wasserstoff, Schwefel und Eisen.
Erlaubt autokatalytische CO2 fixation: chemoautotrophie.
Mineralien könnten organisch Moleküle konzentrieren und kritische Syntheseschritte katalysieren
15
http://www.livescience.com/13363-7-theories-origin-life.htmlA black smoker: site of origin of chemoautotrophic life ? Autocatalytic CO2 fixation: energy from oxidation of FeS 4 HCO3 + 2H+ + 7H2S + 7FeS (CH2-COO-) + 7FeS2 + 8H2O ΔG = -429 kJ/mol
Hypothesen:
Chilly start
Die Sonne war vor 3 Ga weniger hell als Heute
Eis schützt fragile organisch Komponente für UV und Kosmische Strahlung
Molekülen leben langer bei niedrige Temperaturen so dass Schlüsselreaktionen auftreten können.
17
http://www.livescience.com/13363-7-theories-origin-life.html3: Replicating molecules • Spiegelmann (1970) and others – RNA self assembly – self replication (< 10 bases) – Zn catalysed assembly (< 40 bases) – < 1% errors
RNA evolution
RNA in vitro:
RNA template, ribonucleotides, replicase enzyme
few replication errors, selection on replication speed
evolution: 4000 nucleotides to 50, against inhibitionB
U A
G A
C G
Ribozymen
A U
U A
U A
G C
U A
U G
A U
U
G U
E´ C G
U A
A C A B
U
G G A ppp G
5´- G G A A A - 3´
GUUCAUGU GGUU G A A U OH GACC GCAACUU
3´- C U U A U A A G U A C G CCAG
AG
UUUG
A G
UUGG UGUUGAA
G G - 5´
A G G
U
A C
E´ A U
G C
U G
E U
U A
G U
A U
C G
A U
A U
G C
A U
U A
U A
C G
A´ A G
A U
20
Lincoln, T. A. and Joyce, G. F., 2009. Self-sustained replication of an RNA enzyme. Science 323, 1229-1232
U A C G U G U Greplicating RNA enzymes that differ in the re- amplification. Each replicator w
A B
A B
Selbstreplikation
A B
E’
A + B → E (=AB) E´ E´
E
A’ + B’ → E’ E 5´- G
GUU
3´- C U U A U A A
E´
A,B,A’,B’ oligonucleotide
substrates
E E
B´ A´
B´ A´
CHyperzyclus
322 I. SCHEURING ET AL.
Figure 1. Hypercyclic coupling of autocatalytic replicators I1 ,. . . ,I4 .
the cycle assists the replication of I1 (Eigen and Schuster, 1979) (Fig. 1). The chem-
ical nature of the help given to the next member of the hypercycle can be direct
Scheuring, I. Czárán, T.catalysis.
Szabó, P. Each member
Károlyi, G. andcarries two genes:
Toroczkai, oneSpatial
Z., 2003. for theModels
replication, the other
of Prebiotic for the Soup Before Pizza?
Evolution: 22
catalytic
Origins of Life and Evolution help.
of the There is: coexistence
Biosphere The Journal inof the
thenon-spatial model
International of hypercycle:
Society for the Studyallofthe
the Origin of Life 33,
replicators persist in the system and, given an unlimited supply of monomers, the
319-355, 10.1023/A:1025742505324.
total concentration of the macromolecules admits hyperbolic growth. The problem
with this model is its vulnerability to the invasion of two kinds of parasitic mutants:Hyperzyclus Parasiten
SPATIAL MODELS OF PREBIOTIC EVOLUTION: SOUP BEFORE PIZZA? 323
Figure 2. Parasites of the hypercycle. P1 : selfish parasite; P2 : shortcut parasite.
23
and Hogeweg, 1991) that the macromolecules can help each other’s replication
if they happen to be neighbours on a square lattice representing a mineral sur-Replication
• Replicator: self copying entity
– not imply natural selection
• Indefinite hereditary replicator
– indefinite number of states
– each state can be replicated
• Nucleic acid molecules (language, music)
• Nucleic acid molecules basis of lifeChicken -egg problem
• Amount of information transmitted
– limited by replication accuracy
– today: genetically programmed enzymes
– not a primitive state
– RNA world - Ribozymes C G
• 4 nucleotides (C/G, A/U)
A U
• D-anti ribose
•P Why ? G CChemical selection
• Prebiotic pizza
– keeps reactants in each other’s
proximity
– gene interaction only with
neighbours
• directly by influencing each others
replication
• indirectly by catalysing steps of
metabolism
– gene interaction is molecular co-
operation: fitter in struggle for
monomers
– may produce e.g., isoprenoid lipids4: Protobiont formation:
compartimentation
• Like prebiotic pizza
• Enables liberation from surface
• Needs membrane
Glucose phosphate
Liposomes:
Glucose phosphate
Phosphorylase
can be self replicating
Starch
may self metabolise Phosphate Amylase
Maltose
Maltose
but only small molecules (CO2, H2S) pass membraneFirst organism:
Based on Early Earth Environment
This organism is referred to as the Universal or Common
Ancestor. It would have had the following characteristics
because of the environment in which it evolved:
•it would have been anaerobic
•it would have been hyperthermophilic and halophilic
•it would have been a chemolithoautotroph, obtaining
both energy and carbon from inorganic sources, using H2
or reduced sulfur compounds as electron donors and
CO2 or oxidized sulfur as electron acceptors to provide
energy and fixing CO2 as their carbon source.RNA genes to DNA chromosomes • Single gene – A, B faster reproduction than AB • Chromosome – if AB metabolically linked: stay together – no gene competition in cell • DNA – more stable (deoxR-T) – (but RNA needed for protein synthesis)
Life ?
• Two way interaction:
– metabolism supply monomers from which
replicators are made
– replicators alter the kinds of chemical
reactions occurring in metabolismMajor transitions in evolution
Replicating molecules Populations of molecules in
compartments
Independent replicators Chromosomes
RNA as gene and enzyme DNA + protein (genetic code)
Prokaryotes Eukaryotes
Asexual clones Sexual populations
Protists Animals, plants, fungi (cell differentiation)
Solitary individuals Colonies (non-reproductive castes)
Primate societies Human societies (language)Origin of the genetic code • One of most perplexing problems • Why 4 nucleotides (G C A U/T)? • Why triplets, 20 amino acids etc. • Minimise the load
Major transitions in evolution
Replicating molecules Populations of molecules in
compartments
Independent replicators Chromosomes
RNA as gene and enzyme DNA + protein (genetic code)
Prokaryotes Eukaryotes
Asexual clones Sexual populations
Protists Animals, plants, fungi (cell differentiation)
Solitary individuals Colonies (non-reproductive castes)
Primate societies Human societies (language)The three Domains
http://www.kheper.auz.com/gaia/biosphere/kingdoms.htm#five kingdomsAerobic α (purple bact.) Bacterial diversity
Mitochondria
O2 phototrophs
Nitrosomonas chloroplasts
NH4+ to NO2-
γ: Includes H2S Chemo-phototrophs E.g., TBC, Lepra,
botulism, streptomycin
Syphilis,
Lyme
Animal parasitesArchaea
• Extremophiles - PCR
• Normal environments
• Membrane lipids
O
O O
“Normal” bacteria
O and eukaryotes
HO
Thermophilic bacteria
O
Archaea
O
HOMembrane lipids of Archaea
Crenarchaeota Euryarchaeota
(a.o.hyperthermophiles) (a.o. halophiles, methanogens)
OHProkaryote limitations
• Limited size of single chromosome
• limited size multicellular structures (filaments)
• limited cellular differentiation (akinetes)
AnabaenaAnother perplexing problem
– loss outer cell wall -
phagocytosis
– incorporation of organelles
- symbiosis
– development of mitosis
• multiple replication origins
allowing for more DNA
• microtubules /
cytoskeleton
– development of internal
membranes
• nucleus, ER, Golgi app.Eukaryote origin
algal diversity
Transfer of symbiont genes to host nucleusThe three Domains
4 domains?
+ nucleocytoplasmic large DNA virus (NCLDV)
Boyer, M. Madoui, M. -A. Gimenez, G. La Scola, B. and Raoult, D., 2010. Phylogenetic and
phyletic studies of informational genes in genomes highlight existence of a 4th domain of life
including giant viruses. PloS One 5, e15530. 454 domains ?
46Archaea Green and purple nonsulphur bacteria
Important
Common ancestor theory
Trichomonadida
Diplomonadida
Mycobionta
Eukaryote
Rhodobionta
Strameno-
Myxobionta
Euglenozoa
phyles
Alveolata
Animalia
phylogeny
(tentative)
Trypanosoma
Vesicles, alveoli Chloro-
bionta
below outer membrane
No mitochondriaPlastid diversity
Euglenozoa
Glucose polymerAlveolata: ciliates
Alveolata: dinoflagellates
Many toxic speciesStramenophyles: Diatoms Silica wall Several toxic species
Chlorophytes: Volvox
Cellular differentiation
http://protist.i.hosei.ac.jp/PDB/Images/Chlorophyta/Volvox/Okt 2005
J. Eukar. Microbiol. 52(5): 399-451. New Classification of Eukaryotes
• Amoebozoa
– a.o. Heliozoa
• Ophistokonta
– a.o. Fungi, Metazoa
• Rhizaria
– a.o. Foraminifera, Radiolaria
• Archaeoplastida
– a.o. Rhodophyceae, Chloroplastida
• Chlorophyta, Prasinophytae…….: all plants
• Chromalveolata
– a.o. Haptophyta, Stramenophyles, Alveolata
• Coccolitophorids, diatoms, brown algae, dinozoa, cilliata…..
• Excavata
– a.o. Euglenozoa Blue: multicellular lineagesMajor transitions in evolution
Replicating molecules Populations of molecules in
compartments
Independent replicators Chromosomes
RNA as gene and enzyme DNA + protein (genetic code)
Prokaryotes Eukaryotes
Asexual clones Sexual populations
Protists Animals, plants, fungi (cell differentiation)
Solitary individuals Colonies (non-reproductive castes)
Primate societies Human societies (language)
http://www.msu.edu/course/lbs/148h/fall2003/Choanoflagellates
No or primitive cellular
differentiation
Proterospongia
collar and amoeboid cells
http://microscope.mbl.edu/reflections/baypaul/microscope/general/page_01.htmThe Ancestral Metazoan (3)
• It is believed that flagellate protozoans formed a colonial ring of organisms, termed a blastaea.
Development progressed with increasing division of labour to eventually produce a truly multicellular
organism with differentiated cells [Barnes, 1989]. .
The 'blastaea model' of metazoan evolution, derived from a colonial Choanoflagellate.Early embryonic life Animal phylogeny
Development of tissues
Porifera Copyright 1994–2001 by The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California.
Sponge anatomy
No real tissues
cellular differentiationRadiata: e.g. Cnidaria
Cnidaria Fungiid Coral from Indonesia Cubozoan http://www.ucmp.berkeley.edu/cnidaria/cnidaria.html
Platyhelminthes Multicalyx sp. (Trematoda) Polycladid flatworm
Bilateralia: Flatworm
Protostomata
Protostomata: in developing embryo, mouth forms
from first indentation on ball of cells; nervous system
and digestive system cross. Subdivided into two major
groups, the Lophophorates and the Schizocoels.
Lophophorates
! Bryozoa, Brachiopoda,
Phoronida
Schizocoels
! Mollusca , Annelida, Arthropoda
Deuterostomata
Deuterostomata. In the developing embryo
the anus forms from first indentation on ball
of cells and mouth breaks hrough at another
location; nervous system lies at the back side
(dorsal), digestive system in front; the
systems do not cross. Coelom forms from
pockets in the gut.
Chordata, Hemichordata (a.o. graptolites),
EchinodermataDeuterostomata
Secondary radial symmetryChordate characters
Chorda dorsalis
biosci.usc.edu/courses/2002-spring/ documents/bisc113-caron_041902.pdfChordate characters bones, teeth-cores, jaws, neural system
Tunicate
Tunicate Lancelet
Tentacles
Mouth
Pharyngeal slits
Atrium
Intertestine
Dorsal hollow nerve cord Atriopore
Segmental muscles
Anus
Tail
Chorda dorsalisThe amniotic egg
Mammal evolution
Primate evolution
Human evolution
Schritte:
• entstehung des lebens - eukaryote Zelle • Beine
• mehrzelligkeit • Eier
• Zelldifferenzierung • Milchdrüsen
• Gewebebildung • Daumen
• Laterale symmetrie •
• Mesoderm und Coelom
• 2 öffnungen mund/anus
• Chorda, Schwanz....
• Kopf, Vertebrae
• Kiefer
• Lunge
83Early life http://cas.bellarmine.edu/tietjen/Ecology/early_animal_evolution.htm
Currently described species proportion of the global total
64.3
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