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Assignment: Biomolecules Astrobiology and Early Life Biology Lab Worksheet Assignment: Biomolecules Astrobiology and Early Life Biology Lab Worksheet Assignment: Biomolecules Astrobiology and Early Life Biology Lab Worksheet General Biology Lab – Biomolecules, Astrobiology, and Early Life The Origins of Life on Earth The fact that all life on earth utilizes similar classes of biomolecules provides critical insight into how life evolved on earth. For example, this fact suggests that all life currently on our planet evolved from a single common ancestor which made use of these critical biomolecules. One critical question that remains unanswered is how these biomolecules originated. We know that the elements Carbon, Oxygen, Hydrogen, Nitrogen etc… that are the building blocks of these biomolecules come from the sun, however, this doesn’t tell us how they originally organized into what we know today as “biomolecules” such as amino acids and nucleotides. One critical experiment that provides insight into this unanswered question was conducted in the 1950’s. The layout of this experiment is listed below. Your task is to utilize online resources to answer the following questions about the Miller Urey Experiment. A video describing this experiment can be found at: https://tpt.pbslearningmedia.org/resource/buac16-912-sci-essnvlrsmillerurey/wgbh-nova-lifes-rocky-start-the-miller-urey-experiment/#.WnoVgKL4aQg. Or, you can read about the experiment at: http://blogs.discovermagazine.com/notrocketscience/2011/03/21/scientists-finish-a-53-yearold-classic-experiment-on-the-origins-of-life/#.WnoYEKL4aQg. You may also find your own sources for this information. Just be sure that they are credible. Miller Urey Experimental Layout 1. What is the general experimental outline of the Miller-Urey experiment? Page 1 of 6 General Biology Lab – Biomolecules, Astrobiology, and Early Life 2. What does the Miller-Urey experiment tell us about the nature of pre-life Earth? 3. While the Miller-Urey experiment gives us clues as to how the original molecules of life could have initially developed, list several steps that would need to happen before “life” could exist as we know it. (HINT: there are many, many, many potential answers to this question, so spend some time discussing and exploring the idea with your group). Page 2 of 6 General Biology Lab – Biomolecules, Astrobiology, and Early Life 4. NASA scientists have found the same type of molecules as discovered in the Miller-Urey experiment on asteroids and comets. What does this tell you about the prevalence of biomolecules in the galaxy? How does this impact your opinion regarding the “uniqueness” of life? Biomolecules and Astrobiology Please read Chapters 1 and 2 of “The Astrobiology Primer” available to you on D2L. This document is a peer reviewed educational article attempting to provide a broad overview of the field of astrobiology. We will only cover the 1st chapter in this assignment, but feel free to use it to satiate your own curiosity! Based on your reading of “The Primer,” please answer the following questions: 5) What is “astrobiology?” Page 3 of 6 General Biology Lab – Biomolecules, Astrobiology, and Early Life 6) What are your opinions of the field of Astrobiology? 7) Within the field of Biology and/or astrobiology why is it important to define life? 8) Why is it so difficult to define “life?” Page 4 of 6 General Biology Lab – Biomolecules, Astrobiology, and Early Life 9) What are examples of “things” that might not be entirely “alive,” but certainly don’t qualify as “dead?” Provide explanations for what makes these “things” difficult to categorize. What are scientists actually working on? Visit the website found at: Assignment Biomolecules Astrobiology and Early Life Biology Lab Worksheet https://astrobiology.nasa.gov/about/history-of-astrobiology/. Read the article and answer the following questions: 10) What did you find most interesting about this information? Page 5 of 6 General Biology Lab – Biomolecules, Astrobiology, and Early Life 11) Imagine scientists identified life on another planet. Predict what this life would look like? Why might it be similar to life on earth? Why might it be different? The RNA World Theory: Now that you’re experts in all things biomolecules, you’re ready to tackle one of the most controversial theories in all of biology. 12) Please research the RNA World Theory using all of the tools at your fingertips. Click here to ORDER an A++ paper from our Verified MASTERS and DOCTORATE WRITERS: Assignment: Biomolecules Astrobiology and Early Life Biology Lab Worksheet Tell me about what you discover. Page 6 of 6 Education Article ASTROBIOLOGY Volume 16, Number 8, 2016 Mary Ann Liebert, Inc. DOI: 10.1089/ast.2015.1460 The Astrobiology Primer v2.0 Co-Lead Editors Shawn D. Domagal-Goldman and Katherine E. Wright Chapter Editors Shawn D. Domagal-Goldman (Co-Lead Editor, Co-Editor Chapter 1, and Author)1,2,* Katherine E. Wright (Co-Lead Editor, Co-Editor Chapter 1, and Author)3,4,* Katarzyna Adamala (Co-Editor Chapter 3 and Author)5 Leigh Arina de la Rubia (Editor Chapter 9 and Author)6 Jade Bond (Co-Editor Chapter 3 and Author)7 Lewis R. Dartnell (Co-Editor Chapter 7 and Author)8 Aaron D. Goldman (Editor Chapter 2 and Author)9 Kennda Lynch (Co-Editor Chapter 5 and Author)10 Marie-Eve Naud (Co-Editor Chapter 7 and Author)11 Ivan G. Paulino-Lima (Editor Chapter 8 and Author)12,13 Kelsi Singer (Co-Editor Chapter 5, Editor Chapter 6, and Author)14 Marina Walter-Antonio (Editor Chapter 4 and Author)15 Authors Ximena C. Abrevaya,16 Rika Anderson,17 Giada Arney,18 Dimitra Atri,13 Armando Azúa-Bustos,13,19 Jeff S. Bowman,20 William J. Brazelton,21 Gregory A. Brennecka,22 Regina Carns,23 Aditya Chopra,24 Jesse Colangelo-Lillis,25 Christopher J. Crockett,26 Julia DeMarines,13 Elizabeth A. Frank,27 Carie Frantz,28 Eduardo de la Fuente,29 Douglas Galante,30 Jennifer Glass,31 Damhnait Gleeson,32 Christopher R. Glein,33 Colin Goldblatt,34 Rachel Horak,35 Lev Horodyskyj,36 Betül Kaçar,37 Akos Kereszturi,38 Emily Knowles,39 Paul Mayeur,40 Shawn McGlynn,41 Yamila Miguel,42 Michelle Montgomery,43 Catherine Neish,44 Lena Noack,45 Sarah Rugheimer,46,47 Eva E. Stüeken,48,49 Paulina Tamez-Hidalgo,50 Sara Imari Walker,13,51 and Teresa Wong52 *These two authors contributed equally to the work. 1 NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. 2 Virtual Planetary Laboratory, Seattle, Washington, USA. 3 University of Colorado at Boulder, Colorado, USA. 4 Present address: UK Space Agency, UK. 5 Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, USA. 6 Tennessee State University, Nashville, Tennessee, USA. 7 Department of Physics, University of New South Wales, Sydney, Australia. 8 University of Westminster, London, UK. 9 Oberlin College, Oberlin, Ohio, USA. 10 Division of Biological Sciences, University of Montana, Missoula, Montana, USA. 11 Institute for research on exoplanets (iREx), Université de Montréal, Montréal, Canada. 12 Universities Space Research Association, Mountain View, California, USA. 13 Blue Marble Space Institute of Science, Seattle, Washington, USA. 14 Southwest Research Institute, Boulder, Colorado, USA. 15 Mayo Clinic, Rochester, Minnesota, USA. 16 Instituto de Astronomı́a y Fı́sica del Espacio (IAFE), UBA—CONICET, Ciudad Autónoma de Buenos Aires, Argentina. 17 Department of Biology, Carleton College, Northfield, Minnesota, USA. 18 University of Washington Astronomy Department and Astrobiology Program, Seattle, Washington, USA. 19 Centro de Investigación Biomédica, Universidad Autónoma de Chile, Santiago, Chile. 20 Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA. 21 Department of Biology, University of Utah, Salt Lake City, Utah, USA. 22 Institut für Planetologie, University of Münster, Münster, Germany. 23 Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, Washington, USA. 24 Planetary Science Institute, Research School of Earth Sciences, Research School of Astronomy and Astrophysics, The Australian National University, Canberra, Australia. 561 562 DOMAGAL-GOLDMAN AND WRIGHT ET AL. Table of Contents Chapter 1. Introduction—What Is Astrobiology? Chapter 2. What Is Life? Chapter 3. How Did Earth and Its Biosphere Originate? Chapter 4. How Have Earth and Its Biosphere Evolved? Chapter 5. What Does Life on Earth Tell Us about Habitability? Chapter 6. What Is Known about Potentially Habitable Worlds beyond Earth? Chapter 7. What Are the Signs of Life (Biosignatures) That We Could Use to Look for Life beyond Earth? Chapter 8. What Relevance Does Astrobiology Have to the Future of Life on This Planet? Chapter 9. Resources Acknowledgments References Abbreviations List Chapter 1. Introduction—What Is Astrobiology? 1.1. What is astrobiology? A strobiology is the science that seeks to understand the story of life in our universe. Astrobiology includes investigation of the conditions that are necessary for life to emerge and flourish, the origin of life, the ways that life has evolved and adapted to the wide range of environmental conditions here on Earth, the search for life beyond Earth, the habitability of extraterrestrial environments, and consideration of the future of life here on Earth and elsewhere. It therefore requires knowledge of physics, chemistry, biology, and many more specialized scientific areas including astronomy, geology, planetary science, microbiology, atmospheric science, and oceanography. However, astrobiology is more than just a collection of different disciplines. In seeking to understand the full story of 562 563 565 582 589 597 613 623 626 627 627 653 life in the Universe in a holistic way, astrobiology asks questions that transcend all these individual scientific subjects. Astrobiological research potentially has much broader consequences than simply scientific discovery, as it includes questions that have been of great interest to human beings for millennia (e.g., are we alone?) and raises issues that could affect the way the human race views and conducts itself as a species (e.g., what are our ethical responsibilities to any life discovered beyond Earth?). 1.2. Have we already found life beyond Earth? No. There have been many exciting discoveries that suggest life is possible on other planets and moons, but we have not yet detected any definite signs of life beyond Earth. That does not necessarily mean life exists only on Earth, but 25 Earth and Planetary Science, McGill University, and the McGill Space Institute, Montréal, Canada. Society for Science & the Public, Washington, DC, USA. 27 Carnegie Institute for Science, Washington, DC, USA. 28 Department of Geosciences, Weber State University, Ogden, Utah, USA. 29 IAM-Departamento de Fisica, CUCEI, Universidad de Guadalajara, Guadalajara, México. 30 Brazilian Synchrotron Light Laboratory, Campinas, Brazil. 31 School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA. 32 Science Foundation Ireland, Dublin, Ireland. 33 Southwest Research Institute, San Antonio, Texas, USA. 34 School of Earth and Ocean Sciences, University of Victoria, Victoria, Canada. 35 American Society for Microbiology, Washington, DC, USA. 36 Arizona State University, Tempe, Arizona, USA. 37 Harvard University, Organismic and Evolutionary Biology, Cambridge, Massachusetts, USA. 38 Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Budapest, Hungary. 39 Johnson & Wales University, Denver, Colorado, USA. 40 Rensselaer Polytechnic Institute, Troy, New York, USA. 41 Earth Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan. 42 Laboratoire Lagrange, UMR 7293, Université Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, Nice, France. 43 University of Central Florida, Orlando, Florida, USA. 44 Department of Earth Sciences, The University of Western Ontario, London, Canada. 45 Royal Observatory of Belgium, Brussels, Belgium. 46 Department of Astronomy, Harvard University, Cambridge, Massachusetts, USA. 47 University of St. Andrews, St. Andrews, UK. 48 University of Washington, Seattle, Washington, USA. 49 University of California, Riverside, California, USA. 50 Novozymes A/S, Bagsvaerd, Denmark. 51 School of Earth and Space Exploration and Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona, USA. 52 Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri, USA. 26 ª Shawn D. Domagal-Goldman and Katherine E. Wright, et al., 2016; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons Attribution Noncommercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. THE ASTROBIOLOGY PRIMER only that there is not yet compelling evidence for its existence elsewhere. Space missions have explored only a tiny portion of our solar system, and in the few years since we first discovered planets around other stars, the number of such exoplanets known has increased into the hundreds. The search for life beyond Earth has therefore only just begun. Astrobiology is an exciting subject with new ideas that can easily capture the imaginations of both scientists and nonscientists. But like all areas of science, new ideas are subject to detailed scrutiny by the scientific community as part of the quality control process. Only ideas that are considered to be well-supported by evidence are accepted by the scientific community as a whole. This can lead to lively debate within the scientific community and sometimes within the public arena. Whether the new idea is ultimately accepted or not, the process of testing the evidence results in increased knowledge and understanding, not just about the possibility for life beyond Earth but about our own planet as well. Two high-profile announcements within the field of astrobiology illustrate this. In 1996, scientists announced that they had found evidence of fossilized life contained within martian meteorite ALH84001 (McKay et al., 1996). In subsequent years, astrobiologists completed research on the meteorite itself and on the types of ‘‘biosignatures’’ contained within it. As a result, we now know that abiological processes could have created these signals, and the meteorite is not therefore widely considered proof of life beyond Earth (Bradley et al., 1996, 1997; Frankel and Buseck, 2000; Buseck et al., 2001; McKay et al., 2003; Treiman, 2003). For example, one of the ‘‘biosignatures’’ cited by McKay et al. were structures in the meteorite that appeared to resemble fossilized bacteria when viewed under an electron microscope, but later work showed that similar structures can be produced as an artifact of the techniques used to prepare mineral samples for electron microscopy (Bradley et al., 1997). Although the claims made by McKay et al. have not been generally accepted, in the process of testing them astrobiologists advanced research on a variety of topics, including the minimum size of an individual cell and production mechanisms for tiny grains of magnetite. Additionally, astrobiologists were forced to reexamine what constitutes conclusive evidence for past or present life. More recently, a team announced the discovery of a bacterium they claimed could substitute arsenic for phosphorus in its DNA (Wolfe-Simon et al., 2011). These claims have been largely rejected by the scientific community, which has generally concluded that they are not proven by the evidence presented in the paper (Benner, 2011; Borhani, 2011; Cotner and Hall, 2011; Csabai and Szathmáry, 2011; Foster, 2011; Oehler, 2011; Redfield, 2011; Schoepp-Cothenet et al., 2011; Erb et al., 2012; Reaves et al., 2012). Nevertheless, this paper has stimulated a very active debate, and further research will undoubtedly lead to improved understanding of microbial arsenic metabolism. For example, investigations into the claims made by the paper have already led to the hypothesis that the bacteria isolated by WolfeSimon et al. may contain a high-affinity phosphorus transporter that is stimulated by arsenic (Foster, 2011). 1.3. What is the Astrobiology Primer? The Astrobiology Primer is designed to provide a basic, but comprehensive, introduction to the field of astrobiology. 563 It is longer than a typical review paper but much shorter in length than a textbook, with the goal of being detailed enough to provide a brief overview of the variety of questions investigated by astrobiologists. The Astrobiology Primer is the product of a strong, vibrant, early-career astrobiology community. This is the second version of the Primer, and like the first (Mix et al., 2006), it is a grassroots effort, written by graduate students and postdoctoral researchers. In total, we are a group of 49 authors and editors from 14 different countries. This second edition has been rewritten from scratch. It updates content and is organized around the questions that currently drive research in the field. Our target readers for this document are other early-career astrobiologists, in particular graduate students who are new to the field, but we hope that it will also be useful to a wide range of people for both personal study and teaching. This primer begins with the question of the nature of life (Chapter 2), then goes on to discuss the origins of life and its planetary environment (Chapter 3), the interactions of life with our planet through time (Chapter 4), what we know of habitability from these interactions (Chapter 5), what we know about the habitability of environments outside Earth (Chapter 6), and how we might search for life in those environments (Chapter 7). We close with chapters on the implications of this research for society (Chapter 8) and resources for astrobiologists (Chapter 9). Chapter 2. What Is Life? This simple question is surprisingly difficult to answer yet is fundamental to the success of astrobiological research. Imagine the difficulty of identifying life on other worlds without a clear understanding of what similarities it may or may not sha e with life on Earth. Or consider the limitations of interpreting possible origin-of-life scenarios without distinguishing between primitive life-forms and the nonliving entities from which they must have emerged. So far, and not without significant effort, no single definition of life has achieved universal acceptance. But the very exercise of attempting to define life reveals and tests its most essential characteristics. 2.1. Can we define life? The goal is not to define ‘‘life,’’ the word, as it is used and understood in language, but rather to understand ‘‘life’’ as an objective concept that can guide scientific research (Oliver and Perry, 2006). Successful scientific definitions of life attempt to include everything that we already intuitively consider alive and exclude everything that we would not consider alive. For our purposes, such definitions should also be sufficiently broad to include unknown forms of life that independently arose on Earth or elsewhere. If these criteria are satisfied, the definition will be a useful guide in the search for life on other worlds and the study of its origin here on Earth (Ruiz-Mirazo et al., 2004; Oliver and Perry, 2006). This objective, however, is made more difficult to achieve by our lack of a second known instance of life. Because all known life evolved from a single ancestor or ancestral community, every life-form shares a common set of inherited properties (Woese, 1998; Becerra et al., 2007; Theobald, 564 2010). Consequently, it can be difficult to distinguish general features of life in the Universe from those specific to our own form of life (Gayon, 2010). Cleland and Chyba (2002) were the first to argue that, without additional examples of life and the greater understanding they may provide, it is even impossible to know whether the concept of life describes an objective natural phenomenon or a subjective category that cannot be perfectly defined (Cleland and Chyba, 2002; Robus et al., 2009). Such objective phenomena, which philosophers call ‘‘natural kinds,’’ can be defined completely by principles of the natural world without depending on human-made conventions, for example water defined as the molecule H2O. Cleland and Chyba used the term ‘‘bachelor,’’ defined as ‘‘an unmarried adult human male,’’ to illustrate the sort of category that is not a natural kind. This definition ‘‘explain(s) the meaning of (the term) by relating (it) to expressions that we already understand,’’ but the term ‘‘bachelor’’ is not a natural kind in that the terms ‘‘adult’’ and ‘‘unmarried’’ are understood only as cultural concepts, not natural ones. Cleland and Chyba pointed out that ‘‘water’’ was a concept much like this before it became possible to describe water as its molecular formula. Life may be like water, a natural kind waiting for a scientific definition, or may be more like bachelor, a category that can be easily understood but that cannot be defined completely by natural principles. A successful definition of life must not only delineate life and nonlife but also deal with the intermediate stages that may exist between life and nonlife. The origin of life presents just such a test. Our current understanding of life’s origin suggests that there were intermediate states through which all forms of life must emerge (Fry, 1995; Luisi, 1998; Perry and Kolb, 2004). In addition, the biosphere today includes entities that may represent intermediate states between life and nonlife. For example, viruses, which some do not consider bona fide organisms, possess many features similar to organisms and may present further evidence that there is a continuum between life and nonlife. All the arguments listed above demonstrate that the goal of creating a clear and objective scientific definition of life is not at all straightforward. 2.2. What are the common characteristics of life on Earth? While life on Earth represents only one example, it is the only known example and, therefore, a good place to begin. Any universal characteristic of life on Earth may be universal either because it was inherited from a common origin or because it is a necessary feature of all life in the Universe. The lack of a second example of life frustrates our ability to conclusively differentiate between these two possibilities. The chemistry of life is predominated by only a handful of carbon-based macromolecules common to all organisms: cellular membranes and intracellular compartments are primarily composed of a type of molecule called a ‘‘phospholipid,’’ a lipid with a charged phosphate group on one end; genetic information is stored and processed by the nucleic acids DNA and RNA; the catalytic and infrastructural functions of the cell are performed mainly by proteins. Many of DOMAGAL-GOLDMAN AND WRIGHT ET AL. these so-called macromolecules are formed through the polymerization of subunits, for example, nucleotides (forming nucleic acids) and amino acids (forming proteins). The cellular pathway that creates proteins from genetic information is also common across life, and the genetic code that translates genetic information into protein molecules is also nearly universal (Knight et al., 2001). In addition to a common biochemistry, all known lifeforms exhibit many of the same general traits. Campbell and Reece (2002) listed the following traits that are common to life on Earth:        Ordered structure refers to the high level of organization observed both within cells and within multicellular organisms as well as the bilateral or radial symmetry observed in many organisms. Reproduction can refer to either the nearly exact duplication of an organism or the production of a new organism through sex between two parent organisms. Growth and development refers to the processes by which organisms reach maturity, which can take drastically different forms depending on the type of organism. Order Now