Transcript Chapter 21 Adaptation & Speciation

Pertemuan ke-9
Sejarah Kehidupan di
Bumi
Oleh: Dwi Kusuma Wahyuni, S.Si., M.Si.
Departemen Biologi Fakultas Sains dan
Teknologi Universitas Airlangga
Sub Topik
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Asal Usul
Kehidupan di Bumi
Multiselularitas
Pengantar
Beberapa
Episode
Utama
Pada
Sejarah
Kehidupan
di Bumi.
Clock
analogy for
some key
events in
evolutionary
history
Asal Usul Kehidupan di Bumi
1. Bumi diperkirakan terbentuk pada 4.5 miliar tahun yang lalu
2. Membutuhkan waktu 500 juta tahun untuk mendiginkan dan
memadatkan kulit luarnya
3. Fosil-fosil mikroorganisme yang paling tua:
- 3.5 miliar tahun
- pada bebatuan di Australia Barata
3a. Prokaryot-prokariot mendominasi dari tahun 3,5 sampai
2 miliar tahun yang lalu
- Selama waktu ini percabangan pertama terjadi:
bakteria dan Archae
Early and modern prokaryotes
Bacterial mats and
stromatolites
4. Oksigen mulai terakumulasi di atmosfer sekitar 2,7 miliar
tahun yang lalu
a. Cyanobacteria adalah prokariot yang berfotosintesis yang
sampai sekarang memproduksi oksigen
Banded iron formations are evidence of the age of oxygenic
photosynthesis – approximately 2 BYA in photo
5. Fossil eukariota tertua adalah berusia 2 miliar tahun yang
lalu.
a. Komunitas simbiotik prokariotik hidup di dalam
prokariotik lebih besar
 Mitochondria and chloroplasts
6. Fosil organisme multiseluler berusia sekitar 1,2 miliar
tahun yang lalu
Endosymbiosis theory
(Lynn Margulis, 1970’s)
Asal Usul Eukariota
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A. Invaginasi plasma membran
B. Endosimbiosis
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Simbiosis adalah hubungan ekologi antara
organisme 2 spesies yang berbeda yang hidup
bersama-sama dengan kontak langsung
Bagaimana ini dimulai?
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Mangsa atau parasit
Bukti
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Hubungan endosimbiotik
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Biasanya di antara protista
Kesamaan antara eubakteria dan kloroplas
dan mitokondria eukariota
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ukuran
Sistem membran sebelah dalam, enzyme, sistem
transpor elektron
Bereproduksi dengan pembelahan biner
DNA sirkuler
Catatan: kehadiran
dua tipe sel
(fotosintentik dan hold
fast) adalah bukti
spesialisasi fungsi sel
yang penting untuk
perkembangan
organisme multiseluler
7. Fosil Hewan tertua: sekitar 700 juta tahun yang lalu
a. Diversitas Hewan dimulai sekitar 540 juta tahun yang
lalu
Fossilized animal embryos from Chinese sediments
570 million years ago.
8. Tanaman, Jamur dan Hewan mulai menempel di tanah
(tanah sebagai tempat tinggal): 500 juta tahun yang lalu.
a. Tanaman yang pertama menempel di tanah
b. Selanjutnya hewan mengambil keuntungan dari niche
yang baru terbentuk
Mammalia berkembang 50sampai 60 juta tahun yang
lalu.
Hewanhewan
pada era
Cambrian
ASAL MULA KEHIDUPAN
B. Asal mula Kehidupan
1. Sel pertama kemungkinan berasa dari evolusi kimia
meliputi 4 tahap:
a. Sintesis abiotik molukul organik kecil (monomer)
(monomers)  C + H = molekul organik
b. Monomer-monomer bergabung bersama membentuk
polimer-polimer (protein, asam nucleat)
c. Asal mula molekul-molekul self-replicating
(inheritance of traits)  proteins and polynucleic acids
d. Pengemasan molekul organik menjadi protobionts 
Aggregates of abiotically produced molecules that
maintain an internal chemical environment and exhibit
some of the properties associated with life (i.e.
metabolism, excitability).
2. Bukti-bukti yang mendukung empat tahap hipotesis asal
mula kehidupan
a. Oparin and Haldane pada tahun 920s
 Sintesis abiotik synthesis molekul organik dapat diuji di
dalam laboratorium
Hypothesis: Conditions on primitive earth favored chemical
reactions that synthesized organic compounds from inorganic
precursors. These conditions were different from what is now
present and include:
- Reducing environment (no oxygen, but instead H2O, CH4,
NH4, and H2) = lots of free electrons that could be used to
reduce carbon and produce organic molecules.
- Energy from lots of lightning, UV radiation (no O2 to block
UV rays from the sun) and volcanic activity (heat).
b. Miller and Urey Pada 1953
- Tested the Oparin-Haldane hypothesis by creating
conditions in which there was an
- Atmosphere above warmed sea water that contained H2O,
H2, CH4, and NH3 and
- Electrodes that simulated lightning.
- From this setup, they obtained organic compounds such as
amino acids that were collected in cooled water.
Percobaan
Miller-Urey
The experiment - organic molecules could be created out of
inorganic molecules.
So…….why don’t we see this happening in today’s world?
Any organic molecules that are now formed would be
used up by living organisms.
If microorganisms were created from these organic molecules
in the early earth’s water bodies, this would have been an
example of spontaneous creation!
For much of history, man believed that living organisms could
be created spontaneously from non-living material (e.g. flies
from dead meat, geese from barnacles, etc.)
This idea was refuted by Louis Pasteur in the 1860’s.
3. RNA kemungkinan adalah material herediter pertama
a. Hari ini, informasi genetik biasanya dalam bentuk DNA,
tetapi beberapa oraganisme seperti virus dalam bentuk
RNA
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Polimer pendek ribonukleotida dapat disintesis secara
abiotik di laboratorium
PCR
 If these polymers are added to a solution of
ribonucleotide monomers, sequences up to 10 based
long are copied from the template according to the
base-pairing rules.
 If zinc is added, the copied sequences may reach 40
nucleotides with less than 1% error.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 26.11
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Pada tahun 1980 Thomas Cech menemukan bahwa
molekul RNA adalah katalis penting dalam sel moderen.
RNA catalysts disebut ribozymes, membuang intronintron dari RNA.
Ribozymes juga membantu mengkatalis sintesis polimer
RNA yang baru
In the pre-biotic world, RNA molecules may have been
fully capable of ribozyme-catalyzed replication.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
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Laboratory experiments have demonstrated that RNA
sequences can evolve in abiotic conditions.
RNA molecules have both a genotype (nucleotide
sequence) and a phenotype (three dimensional shape)
that interacts with surrounding molecules.
Under particular conditions, some RNA sequences are
more stable and replicate faster and with fewer errors
than other sequences.
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Occasional copying errors create mutations and
selection screens these mutations for the most
stable or best at self-replication.
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RNA-directed protein synthesis may have begun as
weak binding of specific amino acids to bases along
RNA molecules, which functioned as simple templates
holding a few amino acids together long enough for them
to be linked.
 This is one function of rRNA today in ribosomes.
If RNA synthesized a short polypeptide that behaved as
an enzyme helping RNA replication, then early chemical
dynamics would include molecular cooperation as well
as competition.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
4. Prekursor awal kehidupan adalah Protobionts.
a. Protobiont dibentuk secara spontan di laboratorium dari
campuran molekul organik
b. They contain RNA that codes for metabolic proteins.
These protobionts absorb food and the proteins
catalyze it to make energy which can be used for
growth and division to daughter cells.
c. Natural selection would favor protobionts that grow and
replicate. When the organic molecules in the earth’s
water bodies were gone, the protobionts would
“evolve” to either obtain energy by photosynthesis or
predation.
 It would only take the creation and evolution of one (1)
protobiont to give rise to the all the different organisms we
see today.
6. Natural section could refine protobionts containing
hereditary information
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Once primitive RNA genes and
their polypeptide products were
packaged within a membrane,
the protobionts could have
evolved as units.
Molecular cooperation could be
refined because favorable
components
were concentrated
together, rather than
spread throughout the
surroundings.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 26.13
This 4.5 billion-year-old rock, labeled meteorite ALH84001, is believed to have once been
a part of Mars and to contain fossil evidence that primitive life may have existed on Mars
more than 3.6 billion years ago. The rock is a portion of a meteorite that was dislodged
from Mars by a huge impact about 16 million years ago and that fell to Earth in Antarctica
13,000 years ago. The meteorite was found in Allan Hills ice field, Antarctica, by an annual
expedition of the National Science Foundation's Antarctic Meteorite Program in 1984. It is
preserved at the Johnson Space Center's Meteorite Processing Laboratory in Houston.
c. Louis Pasteur in the 1860s
i. Tested whether microorganisms emerge by spontaneous
generation or by reproduction of existing microorganisms.
- Microorganisms grew in open containers of sterilized broth.
C. Major lineages of life
1. At first, two kingdoms were recognized  Plants and
Animals.
2. In 1969, Robert Whittaker developed a five-kingdom
system  Plants, Fungi, Animals, Protists, and Prokaryotes
(Monera).
Whittaker’s
fivekingdom
system
Our changing view of biological diversity