인간의 삶과 역사 속의 미생물

1. 인간의 삶과 역사 속의 미생물 강의자료ppt-5 2011-1학기

2. 조사 과제 1. 과제 내용 미생물이 직접 또는 간접적으로 관련되어 있는 역사적 사건 또는 사실(국내 및 국외) 한 가지를 조사하여 다음과 같은 순서로 작성. 가. 역사적 사건 또는 사실의 명칭 나. 동 사건과 관련되어 있는 것으로 확인되었거나 또는 추정되는 미생물의 정체 다. 사건 또는 사실의 개요(사진이나 그림은 첨부하지 말 것) 라. 참고문헌: 저자, 출판 연도, 제목, 책 또는 논문의 이름, 쪽(페이지; xx-xx) 2. 작성 및 제출 요령: 가. A4용지 2매 이내 나. 한글, 바탕체, 10 points, 160% 다. 편집용지: 기본 다. 파일로 만들어서 이메일로 제출 (young547@yonsei.ac.kr) 라. 파일명: 학번 및 이름 3. 제출 기한: 2011년 4월 30일(토) 밤 12시

3. 생물의 진화와 미생물

4. Formation and Early History of Earth • The Earth is ~ 4.5 billion years old • First evidence for microbial life can be found in rocks ~ 3.86 billion years old (southwestern Green Land)

5. Ancient Microbial Life 3.45 billion-year-old rocks, South Africa

6. Ancient and Modern Stromatolites 3.5 billion yrs old Oldest(Western Australia) 1.6 billion yrs old (NorthernAustralia) Modern stromatolites (Western Australia) Modern stromatolites (WesternAustralia) Modern stromatolites (Yellow Stone NP)

7. More Recent Fossil Bacteria and Eukaryotes From 1 billion yrs old rocks in Central Australia Eukaryotic cells Prokaryotes (bacteria)

8. Origin of Cellular Life • Early Earth was anoxic and much hotter than present day (over 100 oC) • First biochemical compounds were made by abiotic systems that set the stage for the origin of life

9. Surface origin hypothesis • Contends that the first membrane-enclosed, self-replicating cells arose out of primordial soup rich in organic and inorganic compounds in ponds on Earth’s surface • Dramatic temperature fluctuations and mixing from meteor impacts, dust clouds, and storms argue against this hypothesis

10. Subsurface origin hypothesis • States that life originated at hydrothermal springs on ocean floor • Conditions would have been more stable • Steady and abundant supply of energy (e.g., H2 and H2S) may have been available at these sites

11. Submarine Mound Formed at Ocean Hydrothermal Spring Cooler, more oxidized, more acidic ocean water Hot, reduced, alkaline hydrothermal fluid

12. Lipid Vesicles Made in the Laboratory from Myristic Acid vesicle RNAs Vesicle synthesis is catalyzed by the surfaces of montmorillonite clay particles.

13. Last universal common ancestor (LUCA) • Population of early cells from which cellular life may have diverged into ancestors of modern day Bacteria and Archaea

14. As early Earth was anoxic, energy-generating metabolism of primitive cells was exclusively • Anaerobic and likely chemolithotrophic (autotrophic) • Obtained carbon from CO2 • Obtained energy from H2; likely generated by H2S reacting with FeS or UV light

15. Major Landmarks in Biological Evolution

16. A Summary of Life on Earth Through Time

17. Early forms of chemolithotrophic metabolismwould have supported production of large amounts of organic compounds • Organic material provided abundant, diverse, and continually renewed source of reduced organic carbon, stimulating evolution of various chemoorganotrophic metabolisms

18. Microbial Diversification • Molecular evidence suggests ancestors of Bacteria and Archaea diverged ~ 4 billion years ago • As lineages diverged, distinct metabolisms developed • Development of oxygenic photosynthesisdramatically changed course of evolution

19. ~ 2.7 billion years ago, cyanobacterial lineages developed a photosystem that could use H2O instead of H2S, generating O2 • By 2.4 billion years ago, O2 concentrations raised to 1 part per million; initiation of the great oxidation event • O2 could not accumulate until it reacted with abundant reduced materials (i.e., FeS, FeS2) in the oceans • Banded iron formations: iron oxides (e.g. Fe2O3) in laminated sedimentary rocks; prominent feature in geological record

20. Banded Iron Formations Iron oxides

21. Development of oxic atmosphere led to evolution of new metabolic pathways that yielded more energy than anaerobic metabolisms • Oxygen also spurred evolution of organelle-containing eukaryotic microorganisms • Oldest eukaryotic microfossils ~ 2 billion years old • Fossils of multicellular and more complex eukaryotes are found in rocks 1.9 to 1.4 billion years old

22. Consequence of O2 for the evolution of life • Formation of ozone layer that provides a barrier against UV radiation • Without this ozone shield, life would only have continued beneath ocean surface and in protected terrestrial environments

23. Endosymbiotic Origin of Eukaryotes • Endosymbiosis • Well-supported hypothesis for origin of eukaryotic cells • Contends that mitochondria and chloroplasts arose from symbiotic association of prokaryotes within another type of cell

24. Endosymbiotic Origin of Eukaryotes • Evidences • Mitochondria and chloroplasts contain DNA • The eukaryotic nucleus contains genes derived from bacteria • Mitochondria and chloroplasts contains their own ribosomes • Antibiotic specificity • Ribosomal RNA sequencing data

25. Two hypotheses exist to explain the formation of the eukaryotic cell 1) Eukaryotes began as nucleus-bearing lineage that later acquired mitochondria and chloroplasts by endosymbiosis

26. 2) Eukaryotic cell arose from intracellular association between O2-consuming bacterium (the symbiont), which gave rise to mitochondria, and an archaean host

27. The Evolutionary Process • Mutations • Changes in the nucleotide sequence of an organism’s genome • Occur because of errors in the fidelity of replication, UV radiation, and other factors • Adaptative mutations improve fitness of an organism, increasing its survival • Other genetic changes include gene duplication, horizontal gene transfer, and gene loss

28. Evolutionary Analysis • Molecular clocks (chronometers) • Certain genes and proteins that are measures of evolutionary change • Major assumptions of this approach are that nucleotide changes occur at a constant rate, are generally neutral, and random

29. The most widely used molecular clocks are small subunit ribosomal RNA (SSU rRNA) genes • Found in all domains of life • 16S rRNA in prokaryotes and 18S rRNA in eukaryotes • Functionally constant • Sufficiently conserved (change slowly) • Sufficient length

30. Ribosomal RNA 16S rRNA from E. coli

31. Universal Phylogenetic Tree as Determined by rRNA Genes