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Pertemuan ke-9 Sejarah Kehidupan di Bumi Oleh: Dwi Kusuma Wahyuni, S.Si., M.Si. Departemen Biologi Fakultas Sains dan Teknologi Universitas Airlangga.

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Presentasi berjudul: "Pertemuan ke-9 Sejarah Kehidupan di Bumi Oleh: Dwi Kusuma Wahyuni, S.Si., M.Si. Departemen Biologi Fakultas Sains dan Teknologi Universitas Airlangga."— Transcript presentasi:

1 Pertemuan ke-9 Sejarah Kehidupan di Bumi Oleh: Dwi Kusuma Wahyuni, S.Si., M.Si. Departemen Biologi Fakultas Sains dan Teknologi Universitas Airlangga

2 Sub Topik  Asal Usul  Kehidupan di Bumi  Multiselularitas

3 Pengantar

4 Beberapa Episode Utama Pada Sejarah Kehidupan di Bumi.

5 Clock analogy for some key events in evolutionary history

6 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: 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

7 Early and modern prokaryotes

8 Bacterial mats and stromatolites

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13 4. Oksigen mulai terakumulasi di atmosfer sekitar 2,7 miliar tahun yang lalu a. Cyanobacteria adalah prokariot yang berfotosintesis yang sampai sekarang memproduksi oksigen

14 Banded iron formations are evidence of the age of oxygenic photosynthesis – approximately 2 BYA in photo

15 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

16 Endosymbiosis theory (Lynn Margulis, 1970’s)

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18 Asal Usul Eukariota  A. Invaginasi plasma membran  B. Endosimbiosis Simbiosis adalah hubungan ekologi antara organisme 2 spesies yang berbeda yang hidup bersama-sama dengan kontak langsung Bagaimana ini dimulai?  Mangsa atau parasit

19 Bukti  Hubungan endosimbiotik Biasanya di antara protista  Kesamaan antara eubakteria dan kloroplas dan mitokondria eukariota ukuran Sistem membran sebelah dalam, enzyme, sistem transpor elektron Bereproduksi dengan pembelahan biner DNA sirkuler

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22 Catatan: kehadiran dua tipe sel (fotosintentik dan hold fast) adalah bukti spesialisasi fungsi sel yang penting untuk perkembangan organisme multiseluler

23 7. Fosil Hewan tertua: sekitar 700 juta tahun yang lalu a. Diversitas Hewan dimulai sekitar 540 juta tahun yang lalu

24 Fossilized animal embryos from Chinese sediments 570 million years ago.

25 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.

26 Hewan- hewan pada era Cambrian

27 ASAL MULA KEHIDUPAN

28 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).

29 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 H 2 O, CH 4, NH 4, and H 2 ) = lots of free electrons that could be used to reduce carbon and produce organic molecules. - Energy from lots of lightning, UV radiation (no O 2 to block UV rays from the sun) and volcanic activity (heat).

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32 b. Miller and Urey Pada Tested the Oparin-Haldane hypothesis by creating conditions in which there was an - Atmosphere above warmed sea water that contained H 2 O, H 2, CH 4, and NH 3 and - Electrodes that simulated lightning. - From this setup, they obtained organic compounds such as amino acids that were collected in cooled water.

33 Percobaan Miller-Urey

34 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.

35 3. RNA kemungkinan adalah material herediter pertama a. Hari ini, informasi genetik biasanya dalam bentuk DNA, tetapi beberapa oraganisme seperti virus dalam bentuk RNA

36  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 CummingsFig

37  Pada tahun 1980 Thomas Cech menemukan bahwa molekul RNA adalah katalis penting dalam sel moderen.  RNA catalysts disebut ribozymes, membuang intron- intron 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

38  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. Occasional copying errors create mutations and selection screens these mutations for the most stable or best at self-replication.

39  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

40 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.

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42  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. 6. Natural section could refine protobionts containing hereditary information Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

43 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 It is preserved at the Johnson Space Center's Meteorite Processing Laboratory in Houston.

44 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.

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47 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).

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49 Whittaker’s five- kingdom system

50 Our changing view of biological diversity


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