EXAM 2 Review

EXAM 2 Review - ExamTwoReview Chapter21 I....

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Exam Two Review Chapter 21 I. Conditions for life a. Reducing atmosphere (little free oxygen- most was tied up in compounds) i. Importance- oxygen is very reactive and would have oxidized all the  molecules that are necessary building blocks in the origin of life b. UV rays from the sun, thunder and lightning, volcanic activity i. Importance- provided the energy to build biological molecules from  inorganic chemicals c. Presence of chemical building blocks (water, mineral, and gases) d. Time  i. Time for things to accumulate and react with one another II. How Precursors of Life Originated a. Prebiotic Soup Hypothesis i. Molecules formed near earth’s surfaces ii. Polymerization formed spontaneously from monomers on hot rock or clay  surfaces iii. Clay contains zinc and iron that may have served as catalysts 1. Experiment:  Miller and Urey a. Could organic molecules form in a reducing atmosphere? i. Took gases ( NH3, CH4, H2, and water vapor) ii. Provided a spark (simulating light) iii. Simple amino acids condensed b. Iron-Sulfur World Hypothesis i. Molecules formed at cracks in the ocean’s floor ii. Hot water with carbon monoxide and minerals (like sulfides of Fe and Ni) iii. Ammonia rich environments 1. One of the precursors of proteins and nucleic acids III. Major Steps in the Origin of Cells a. After the first polymers formed, could they have assembled spontaneously into  more complex structures?  IV. Protobionts
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a. Macromolecular assemblages that exhibit many functional and structural  attributes of living cells, such as homeostasis, beginnings of metabolism, and  divide after being “grown” b. Cells arose from these aggregations of non living molecules c. Pharmaceutical companies use these to deliver drugs i. Are assemblages of abiotically (not made by organisms) produced  organic polymers V. RNA- first informational molecule to evolve a. Has catalytic properties (ribozymes)  i. May have catalyzed its own replication in clay 1. It acted as its own substrate and enzyme ii. Could have also catalyzed all biologically important reactions leading to  the progress of a self-replicating cell and proteins b. Evolved into DNA  i. When it began making double stranded copies  1. Would have done this because DNA’s helical shape is much more  stable   c. Can in vitro natural selection result in chemical evolution of catalysts, and could  these molecules have catalyzed the many different reactions necessary for life? i.
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This note was uploaded on 02/12/2011 for the course BIO 101 taught by Professor Martin during the Fall '08 term at Rutgers.

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EXAM 2 Review - ExamTwoReview Chapter21 I....

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