AST10 - Astrobiology and Life in the Universe PDF

AST10 - Astrobiology and Life in the Universe Introduction to Astrobiology Astrobiology - Astrobiology is the scientific study that seeks to understand the origins, evolution, distribution, and future of life in the universe. - It combines insights from var...

AST10 - Astrobiology and Life in the Universe Introduction to Astrobiology Astrobiology - Astrobiology is the scientific study that seeks to understand the origins, evolution, distribution, and future of life in the universe. - It combines insights from various scientific disciplines, including astronomy, biology, chemistry, geology, and planetary science. Extremophiles - Organisms that thrive in extreme environments. - They are considered as analogs for potential life forms on other planets. Habitability - Refers to the conditions necessary for life to arise and persist. - It includes the presence of liquid water, a stable environment, and the availability of key elements such as: Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur Goldilocks Zone - Region where conditions are just right for liquid water to exist on a planet’s surface.  SOME REQUIREMENTS OF LIFE Liquid Water - Needed for chemical reactions and as a transport medium. Atmosphere - Needed to avoid rapid vaporization of water; gasses needed for organic compounds. Moderate Temperatures - Important to keep water liquid; avoid disintegration of organic compounds; activate complex chemical reactions). Time - Needed for life to evolve from simple organic compounds into higher life forms: several billion years LIFE’S ORIGIN AND EVOLUTION Abiogenesis - It explores how life might have originated from non-living matter. Miller-Urey Experiment - This experiment demonstrated that the organic compounds could form from simple molecules under early Earth-like conditions. - This experiment was conducted in 1952. It simulated the condition of Earth when life began 4 billion years ago. RNA World Hypothesis - This suggests that self-replicating RNA molecules could have been precursors to cellular life. Astrobiology and Space missions - Various space missions and rovers have been sent to explore the potential habitability of other planets and moons in our solar system, such as Mars, Europa, and Enceladus. - The search for microbial life, past or present, is a key focus of many of these missions. SETI: The Search for Extraterrestrial Intelligence - This involves monitoring signals from space for any potential signs of intelligent extraterrestrial civilizations. Ethical and Philosophical Implications of Astrobiology - Astrobiology raises important questions about our place in the universe, the nature of life, and our responsibilities if we do discover extraterrestrial life. - It also prompts discussions about how we should approach contact with potential extraterrestrial civilizations. The Origin of Life 1. Theory of Special Creations - This proposed that life on Earth is created by a supernatural power, the God.  2. Spontaneous Generation - According to Aristotle, it is the notion that life can arise from non-living matter. - Pneuma (“Vital Heat”) - The appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. Scientists that approved in the Spontaneous Generation Theory: Aristotle Jan Baptista Van Helmont - He is a 17th Century Flemish scientist - He said that mice could arise from rags and wheat kernels.  John Needham - Briefly boiled broth infused with plant or animal matter, hoping to kill all pre-existing microbes. Lazzaro Spallanzani - First agreed but later on contradicted with needham DISPROVING SPONTANEOUS GENERATION Francesco Redi - He is an Italian physician - He refuted Spontaneous generation - He demonstrated that the presence of maggots in putrefying meat does not result from spontaneous generation but from eggs laid on the meat by flies.  Louis Pasteur - Refuted the long-disputed theory of spontaneous generation - Correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. 3. The Miller-Urey Experiment - Stanley L. Muller & Harold C. Urey - The early earth’s atmosphere was able to produce amino acids from inorganic matter - Methane, water, hydrogen, and ammonia which they considered were found in the early earth’s atmosphere - Miller and Urey examined the cooled water after a week and observed that 10-15% of the carbon was in the form of organic compounds. 2% of carbon had formed 13 amino acids.  4. OPARIN & HALDANE Oparin - The organic compounds would have undergone a series of reactions to form complex molecules. Haldane - The atmosphere of the primordial sea was devoid of oxygen, and was composed of ammonia, carbon dioxide, and ultraviolet light. - The sea contained large amounts of organic monomers and polymers, and the sea was called a ‘hot dilute soup’. 5. RNA World Hypothesis - Carl Woese, Francis Crick, and Leslie Orgel (1960’s) - They said that life on Earth began with a simple RNA molecule that could copy itself without help from other molecules. - The discovery that RNA can act as both a store of genetic information and as a cellular catalyst. - RNA is capable of self-replication and could therefore have carried genetic information across generations independently. 6. Hydrothermal Vent Hypothesis - When heated, mineral-laden seawater spews from cracks in the ocean crust, creating a gradient in positively charged protons that serve as a "battery" to fuel the creation of organic molecules and proto-cells. 7. Panspermia - It is the hypothesis that life exists throughout the Universe, distributed by space dust, meteoroids, asteroids, comets, and planetoids. CURRENT RESEARCH A study published in the Journal of Physical Chemistry A - A team of researchers led by Michel Farizon of the University of Lyon and Tilmann Märk of the University of Innsbruck has now made a significant discovery in the field of abiotic peptide chain formation from amino acids for the smallest occurring amino acid, glycine, a molecule that has been observed several times extraterrestrially in recent years.  Evolution 536 AD - Considered as the “Worst Year in Human History”. - According to Michael the Syrian, “The sun darkened and this darkness lasted 18 months. Each day lasted about four hours, and this light was only a faint shadow. It was believed that the sun will never regain its light. The fruits did not ripen and the wine tasted like sour grapes.” - According to Procopius of Caesarea. “This year, the greatest miracle happened: the whole year the sun emitted light like the moon, without rays, as if it was losing its strength, having ceased, as before, cleanly and brightly asleep. Since this began, no war has stopped among people, nor pestilence, nor any other calamity that brings death. Then it was the tenth year of Justinian’s reign.” Evolution - It is the process of gradual change in species over time. Charles Darwin - Species can change over time, that new species come from pre-existing species, and that all species share a common ancestor. - Darwin's theory of evolution through natural selection are: 1. More individuals are produced than can survive; 2. There is therefore a struggle for existence; 3. Individuals within a species show variation; and 4. Offspring tend to inherit their parents' characters.  THE THEORY OF NATURAL SELECTION Natural Selection - It is the process through which species adapt to their environments. It is the engine that drives evolution. - It is one of the processes that drives evolution and helps to explain the diversity of life on Earth. EVIDENCE FOR EVOLUTION Fossil Records Comparative Anatomy Molecular Biology Biogeography ADDITIONAL INFORMATION: 1. Fossil Records 2. Comparative Anatomy - The study of similarities and differences among structures of living species. Homologous Structures - Body parts of different species with similar structures but different functions. - Evidence of a close evolutionary relationship (recent common ancestor).  Analogous Structures - These are features which have different structures but similar functions. Shows no common ancestors. Vestigial Organs/ Vestigial Structures - These are kinds of structures that have little importance for organisms but are historical remnants of evolutionary ancestors. - These organs are non-functional features fully developed and functioning in earlier species but serve little or no present purpose for an organism. - Examples: Ostrich wings, human appendix, wisdom teeth, whale, and snake pelvis/hind legs. 3. Molecular Biology - This is the study of the chemical structures and processes of biological phenomena that involves the basic units of life, molecules. - Through this study, the scientists discovered that closely related species share higher percentages of sequences than species that are distantly related. They discovered it by examining the nucleotides of DNA and amino acid sequence of proteins from different species. 4. Biogeography - refers to the distribution of various species and ecosystems geographically and throughout geological time and space. - Patterns in distribution of living and fossil species can show evolutionary patterns. - These two patterns are: 1. Closely related but different species live in slightly different habitats. 2. Distantly related but similar species live in similar habitats around the world. Types of Biogeography: (Not included in the lessons and references given) Conservation Biogeography: This study involves the application of biogeographical principles, theories, and analyses to problems regarding biodiversity conservation. This study provides predictions about the fate of key species and ecosystems over the next century. Evolutionary Biogeography: This is the study of the factors that define the spatial distribution of species in the present time. It also examines the contributing factors for the global distribution of plants and animal species, such as climate, habitat, and primary productivity. Historical Biogeography: Also known as “Paleobiogeography”, investigates the evolutionary history of species and past climate change to determine why a certain species may have developed in a particular area. The Tree of Life - The tree of life or universal tree of life is a metaphor, model and research tool used to explore the evolution of life and describe the relationships between organisms, both living and extinct, as described in a famous passage in Charles Darwin's On the Origin of Species (1859).  THE MECHANISMS OF EVOLUTION Genetic Drift - The change in frequency of an existing gene variant due to random chance. Gene Flow - It is the movement of alleles between populations. - It occurs when individuals join new populations and reproduce. - Gene flow keeps neighboring populations similar. - Low gene flow increases the chance that two populations will evolve into different species.  DIFFERENCES BETWEEN GENETIC DRIFT AND GENE FLOW Speciation - It occurs when a group within a species separates from other members of its species and develops its own unique characteristics. - 2 types of speciation are: Allopatric speciation: one population is divided by a geographical barrier. Sympatric speciation: one population is divided into different groups based on behavioral changes. Extinction and Mass Extinction - Mass extinction event is when species vanish much faster than they are replaced. - This is usually defined as about 75% of the world's species being lost in a short period of geological time - less than 2.8 million years. IMPACT OF EVOLUTIONARY BIOLOGY Evolutionary Biology - This is the study that examines the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. - It is also the study of the history of life forms on Earth. Impacts - Seeks to explain the diversity of life: the variety of organisms and their characteristics, and their changes over time. - Help us to comprehend human impacts on the global ecosystem and find measures to achieve more sustainable development. COMMON MISCONCEPTIONS AND CONTROVERSIES RELATED TO EVOLUTION CREATIONISM VS. EVOLUTION  The Search for Extraterrestrial Life WHAT IS EXTRATERRESTRIAL LIFE? Extraterrestrial Life - Also known as “Alien Life”, is life which does not originate from Earth. - No extraterrestrial life has yet been conclusively detected. - Such life might range from simple forms such as prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humanity. WHY DO WE SEARCH IT? - SETI is essential to the survival of humanity. - This is to ensure the continuity of existence of species. HOW DO WE SEARCH IT? - Exploring and illuminating the world of extreme life on Earth; - Experimenting with how life here began; - Understanding more about the chemical makeup of the cosmos; - Testing for habitability on missions to Mars, Jupiter’s moon Europa, Saturn’s moon Titan, and beyond: - An enormous body of science is being assembled to analyze and explain the origins, characteristics and possible extraterrestrial dimensions of life.  METHODS OF SEARCHING FOR EXTRATERRESTRIAL LIFE Direct Detection - Looking for signals from other civilizations. Indirect Detection - Looking for evidence of life, such as biosignatures Simulations - Using computer models to predict where and how life might exist. - Example: SETI60 (a mobile app that allows you to listen to real-time radio data from the SETI@home project) PAST SEARCHES FOR EXTRATERRESTRIAL LIFE Project Ozma - The first attempt to detect radio signals from other stars. First attempt to detect SETI. - The objective of the experiment was to search for signs of life in distant planetary systems through interstellar radio waves. - It was conducted in 1960 by Cornell University astronomer Frank Drake, at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. - The program was named after Princess Ozma, ruler of the fictional land of Oz, inspired by L. Frank Baum's supposed communication with Oz by radio to learn of the events in the books taking place after The Emerald City of Oz. - The telescope was aimed at two nearby stars (Epsilon Eridani and Tau Ceti, both about 11 light-years from the Earth) that resemble the Sun and seem reasonably likely to have inhabited planets. A special receiver was attached to the telescope to listen for narrow-band radio signals at the frequency of 21 centimeters, which is the wavelength of radiation emitted naturally by interstellar hydrogen. This was thought to be a likely frequency for extraterrestrial civilizations to use, as it is a common and easily detectable wavelength. SETI@home - Collective effort by the volunteering public - A distributed computing project that searches for radio signals from other stars. - The project was launched in 1999, and it quickly became one of the most popular volunteer computing projects in the world. At its peak, it had over 5 million users and was processing data from over 100 million radio telescopes. - SETI@home works by dividing the data from radio telescopes into small chunks and distributing them to volunteers' computers. The volunteers' computers then analyze the data for patterns that could be signs of extraterrestrial intelligence. Kepler Space Telescope - A mission that has found thousands of exoplanets. - Kepler Space Telescope was launched by NASA in 2009 to search for exoplanets, or planets that orbit stars other than the Sun. Kepler used the transit method to find exoplanets, which means that it looked for the slight dips in brightness that occur when a planet passes in front of its star. - Kepler was a very successful mission, and it found over 2,600 exoplanets, including many that are similar to Earth in size and orbit. The telescope was retired in 2018, but its legacy continues. The data that Kepler collected is still being analyzed, and it is helping astronomers to learn more about the formation and evolution of exoplanets.  CURRENT SETI PROJECTS Breakthrough Listen: This project is using the world's most powerful radio telescopes to search for extraterrestrial intelligence. SETI@home: This project uses volunteer computing to analyze radio data for signs of extraterrestrial intelligence. METI (Messaging Extraterrestrial Intelligence): This project is sending messages to other civilizations in the hope of making contact. The Allen Telescope Array: This is a radio telescope array that is being used to search for extraterrestrial intelligence. FUTURE RESEARCHES James Webb Telescope (JWST) - A telescope that will be able to study exoplanets in more detail. Breakthrough Listen - A project that is using a radio telescope to search for signals from other stars. Project Blueshift - A project that is using a spectrograph to search for biosignatures in the atmosphere of exoplanets. TIMELINE OF THE SEARCH FOR EXTRATERRESTRIAL LIFE  MAP OF THE EXOPLANETS THAT HAVE BEEN DISCOVERED - NASA just dropped an astonishingly elaborate map of more than 4,000 exoplanets known to exist outside our Solar System, which takes the form of a video that shows how many exoplanets we've discovered each year since 1991. THE ETHICAL IMPLICATIONS OF FINDING EXTRATERRESTRIAL LIFE - What obligations will we have to Extraterrestrial life? - What obligations will it have to us?  Chemistry of Life: Exploring the Chemical Basis of Life Atoms - Smallest unit into which matter can be divided without the release of electrically charged particles. - A particle of matter that uniquely defines a chemical element. - The basic building block of matter. - Particles that consist of a nucleus of protons and neutrons surrounded by an electromagnetically-bound cloud of electrons. Atomic Structure - The structure of an atom comprising a nucleus (center) in which the protons (positively charged) and neutrons (neutral) are present. Elements - Pure substances made up of only one type of atom. - Some examples of elements are iron. Copper, Silver, Gold, Hydrogen, Carbon, Nitrogen, and Oxygen. Compounds - Pure substances made up of two or more different types of elements. - Some examples of compounds are Sugar (sucrose - C12H22O11), Table salt (sodium chloride - NaCl), Water (H2O), Carbon dioxide (CO2), and Sodium bicarbonate (baking soda - NaHCO3). The Periodic Table - It is the organized array of all the chemical elements in order of increasing atomic number. - Calcium, carbon, chlorine, cobalt, copper, fluorine, hydrogen, iodine, iron, magnesium, manganese, molybdenum, nitrogen, oxygen, phosphorus, potassium, selenium, sodium, sulfur, and zinc are regarded as the 21 elements essential for life. Chemical Bonds - An attraction between atoms; - This attraction may be seen as the result of different behaviors of the outermost or valence electrons of atoms. - These behaviors merge into each other seamlessly in various circumstances, so that there is no clear line to be drawn between them. - There are kinds of chemical bonds. These are: Covalent bond: The atoms are bound by shared electrons. Metallic bond: This is a force that holds atoms together in a metallic substance. Non-covalent bond: This is a bond in which no sharing of electron pairs takes place. It occurs mostly between the macromolecules and is weaker than the covalent bond. Ionic bond: the atoms are bound together by the attraction of oppositely charged ions. Hydrogen bond: A weak chemical bond and happens when a hydrogen atom that is already bound to an electronegative atom in a molecule, forms a bond with another electronegative atom in the same molecule or different one.  ORGANIC VS. INORGANIC COMPOUNDS Organic compounds - Derived from or produced by living organisms and have carbon-hydrogen covalent bonds. - Carbon is the central element in compounds necessary for life-organic compounds; - Compounds include carbohydrates, lipids, proteins and nucleic acids. Inorganic compounds - Derived from nonliving components, and generally have ionic bonds, lack carbon-hydrogen bonds, and rarely, if ever, contain any carbon atoms. Macromolecules - Any very large molecule, usually with a diameter ranging from about 100 to 10,000 angstroms (10−5 to 10−3 mm); - Provide structural support, a source of stored fuel, the ability to store and retrieve genetic information, and the ability to speed biochemical reactions. - These are basically polymers, long chains of molecular sub-units called monomers. - Carbohydrates, proteins and nucleic acids are found as long polymers. Carbohydrates - Carbohydrates, or carbs, are sugar molecules. Along with proteins and fats, carbohydrates are one of three main nutrients found in foods and drinks. - Act as an energy source, help control blood glucose and insulin metabolism, participate in cholesterol and triglyceride metabolism, and help with fermentation. - They are energy production, energy storage, building macromolecules, sparing protein, and assisting in lipid metabolism. Lipids - Lipids are fatty, waxy, or oily compounds that are essential to many body functions and serve as the building blocks for all living cells; - They're part of your cell membranes and help control what goes in and out of your cells; - They help with moving and storing energy, absorbing vitamins and making hormones; - The four main groups of lipids include: Fatty acids (saturated and unsaturated) Glycerides (glycerol-containing lipids) Non Glyceride lipids (sphingolipids, steroids, waxes) Complex lipids (lipoproteins, glycolipids) Proteins - Proteins are large, complex molecules that play many critical roles in the body; - They do most of the work in cells and are required for the structure, function, and regulation of the body's tissues and organs; - Proteins are responsible for nearly every task of cellular life, including cell shape and inner organization, product manufacture and waste cleanup, and routine maintenance. - Proteins also receive signals from outside the cell and mobilize intracellular response. Nucleic Acids - Nucleic acids are large biomolecules that play essential roles in all cells and viruses; - A major function of nucleic acids involves the storage and expression of genomic information; - Nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA); - Carry genetic information which is read in cells to make the RNA and proteins by which living things function. Chemical Reactions - A process in which one or more substances, the reactants, are converted to one or more different substances, the product Substances are either chemical elements or compounds. - Some examples of activities incorporating chemical reactions: Burning fuels, smelting iron, making glass and pottery, brewing beer, and making wine and cheese. Enzymes - Essential for respiration, digesting food, muscle and nerve function, among thousands of other roles. - Help speed up chemical reactions in the human body - They are proteins that help speed up metabolism, or the chemical reactions in our bodies. - There are 11 enzymes in the human body: Amylase (EC 3.2.1.1) Sucrase (EC 3.2.1.10) Chitinase (EC 3.2.1.14) Lysozyme (EC 3.2.1.17) Maltase (EC 3.2.1.20) Lactase (EC 3.2.1.23) Beta-galactosidase (EC 3.2.1.23) Hyaluronidase (EC 3.2.1.35) pH and Buffers - Biological systems use buffers to maintain pH; - A buffer is a solution that resists a significant change in pH upon addition of an acid or a base. - A pH value is an indication of how acidic or alkaline a substance is. - Regulating the acid-base balance or the body pH is vital for maintaining homeostasis in biological systems.