GEO 102 Lecture 24 Outline of Last Lecture I. The Beginning of the Earth Outline of Current Lecture II. What is Life?III. What are Living Things made of?IV. ExperimentsV. ProteinsCurrent LectureWhat is Life?- How do we know something is alive?o How is a rock different from a tree?o Reproductiono Metabolism- a sequence of chemical reactions- What is a Virus?o Not aliveo It has DNAo It reproduceso But it can’t reproduce by itself It has to hijack a cell in some other bodyo It doesn’t metabolize by itself eithero Outside another body it simply existso Viruses evolveBetween life and not-life- Viruses are in a grey area- They DO NOT represent the first proto-life- Microspheres might better resemble the first lifeo They are organic (carbon based) but arise by themselveso They grow and divide like cells- but more randomlyWhat are living things made of?These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Amino acids- life’s building blocks o You may have heard of them from your foodo Can originate from non-living things- How did they originally form?o Miller-Urey experimento Chemosynthesiso Geobiology Did life come from rocks or clay or undersea volcanoes? Many think soHow do they make amino acids?- You need:o Carbon, nitrogen, hydrogen, and oxygeno These are in the early atmosphere CO2, H2O,N2, CH4, and NH4o An external energy source is needed to start the reactiono Lightningo Chemical energyExperiments- Miller-Urey showed it could be done, but used the wrong atmosphere- More recent work has done this in a wide variety of circumstances- Several possible “cradles” of early life have been identified- This is but the first step thoughProteins- Amino acids are part of proteins- Our bodies synthesize proteins- How did they begin?o Simple “proteinoids” have been formed in the labo Experiments suggest that it may not have happened in water after all - Group of protenoids cluster and form cell-like structures protected by membranesIs this how it happened?- There is still a lot to be learned and it is developing story –RNA and DNAo Reproductiono Space?- The geological record’s earliest evidence of life is in indirecto Stable carbon isotopes at 3.8 bya- The first undisputed fossils show up about ~3.5 byao Prokaryotico Anoxic- can not live without oxygenWhat did these organisms eat?- The earliest life is derived energy from breaking down components in their environmento Would not have lasted long- Later life would ferment materialso Molecules such as sugars are split releasing carbon dioxide, alcohol, and energy- About 3.5 bya photosynthesis began to be widespread- Take home tip: how oxygen became popular. One way didn’t require life- Phot and chemosynthesis. Life is from building blocks that can self-assemble. Still looking for how to tell if things are life- life in extreme environments and making synthetic
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