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BIOL 2061 1st Edition Lecture 2 Outline of Last LectureI. Learning Assistance, Teaching Assistance A. Office hours II. Course Learning ObjectivesIII. Resources for this classIV. GradingV. Due datesOutline of current lectureI. How did life began on EarthII. When did life begin on EarthIII. 4 overlapping stages of lifeIV. Advantages to DNA/RNA/proteinsLectureI. How did life begin on Earth?a. Big ideas:i. There’s no way to be certain about how long life has been in existenceii. Earth is really, RREEAALLYY old!iii. Conditions on earth have been changing and will remain changingiv. The organisms on earth has changed and always will changeb. Beginning of Universei. Current Theory is the Big Bang1. The big bang happened about 13.7 billion years ago2. Resulted I the formation of hydrogen and Helium (the simplest atoms)3. The gravity of the Earth collapsed the clouds of H and He into starsThese 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.4. The stars formed heavier elements of Carbon, Nitrogen and OxygenII. Some numbersi. Super Nova (Exploding star) 4.6 billion years ago- Created the planetsii. Earth is about 4.55 billion years oldiii. 4 billion years ago the Earth cooled and solidifiediv. About 3.5 billion years ago life likely startedIII. 4 Over lapping stages of lifea. Nucleotides and amino acids formb. Nucleotides join to form DNA, RNA and amino acids join to make proteinsc. Membranes enclose the DNA, RNA and proteinsd. Polymers enclosed in membranes evolved cellular propertiesi. Nucleotides and amino acids form (Stage 1)Hypothesis NotesReducing atmosphere hypothesis - Early earth would be rich in water- Rich in hydrogen gas- Rich in ammonia- Rich in methane- NO OXYGENMiller and Urey created an apparatus to mimicthe Earth’s atmosphere conditions and with their invention they were able to create aminoacids, sugars and nitrogenous gases(used electrical spark to emulate lightning strikes)Extraterrestrial Hypothesis - Scientist believed carbon arrived on asteroids and comets that struck Earth.- A good amount of meteorites contain carbon- The major argument that goes against this hypothesis is that other amino acids and nucleic acids would’ve been destroyed by the heat of the objectscoming into Earth’s atmosphereDeep Sea Vent Hypothesis - Biologically important molecules could’ve formed in the temperature gradient- Supported by experiments lots of complex life had been found near the sea vents- Life so far below the surface get their energy from hydrogen sulfideii. Oragnic Polymers (stage 2)1. Polymers= a chain of monomers2. Prebiotic synthesis of polymers has been found hard to make in water3. A better way to make polymers is on a clay surface4. Clay works great because it has both (+) and (-) charges and it acts as a clamp. It claps onto a monomer and then connected to another monomer, finally making a polymeriii. Membranes enclose polymers (Stage 3)1. A big characteristic of a cell is the nucleus2. A membrane encloses some polymers in a solution3. Cells may have evolved froma. Coacervates- A skin of water around a solid ball proteins and carbohydrates.b. Liposomes- A layer of phospholipids that surround a sphere of water (like the cells we know of today)iv. Polymers enclosed in the membranes evolved cellular properties1. Scientist favor RNA being the first macromolecule of protobionts2. 3 major functions of RNAa. Ability to store in formationb. Ability to replicatec. Enzymatic function3. DNA does not have all 3 of these functionsIV. Advantages of RNA/DNA and protein worlda. Central Dogma DNA RNA Proteinb. Information storagei. DNA took over information retaining role ii. Allowed for RNA to have other functions—make proteinsiii. DNA is less likely to suffer from mutationsc. Metabolism and other cellular functionsi. Proteins have a high catalytic potential and efficiencyii. Proteins can perform other tasks--- cytoskeleton, transport,


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