Review_Exam1 - Living organisms operate within the same...

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1 Living organisms operate within the same physical laws that apply to physics and chemistry: Conservation of mass, energy Laws of thermodynamics Laws of chemical kinetics Principles of chemical reactions These physical laws describe several axioms that make up the Molecular Logic of Life. These axioms define •Energy converted to work •Catalytic chemical transformations •Assembly of molecules with great complexity from simple subunits. •Complex molecules combine to form supra molecular components, organelles and finally assemble into a cell. •Store and pass on instructions for the assembly of all future generations from simple non-living precursors
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2 Prebiotic World Living matter consists of a small number of elements Elemental composition of the human body (97%) •Trace: B, F, Si, V, Cr, Mn, Fe, Co, Cu, Zn, Se, Mo, Sn, I •Most organisms are ca. 70% water •The earth is ca. 4.6 billion years old. •Earliest known fossil is ca. 3.5 billion years old (filamentous bacterium).
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3 Prebiotic World Early atmosphere probably consisted of H 2 O, N 2 , CO 2 , with small amounts of CH 4 , NH 3 , SO 2 , and H 2 Sparking of a mixture of CH 4 , NH 3 , H 2 O, and H 2 for 1 week yielded (Stanley Miller and Harold Urey) •Acids (formic, glycolic, lactic, propionic, acetic, succinic, aspartic, glutamic, etc.) •Amino acids (glycine, alanine, aspartic, glutamic) •Others (urea, sarcosine, N-methyl-alanine, N-methyl- urea, etc.) The above experiments were meant to mimic the effects of lightening on the prebiotic atmosphere. This has been challenged by some scientists who propose that early biological molecules were created in the dark underwater at hydrothermal vents, where heat stable bacteria live today.
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4 • Organic Functional Groups - you must know these • They will show up time and time again in Biochemistry • Note that the charge state of some of the groups above will differ in different environments/conditions (e.g., COOH and COO-; NH 3 and NH 4 +) Key Organic Functional Groups
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5 • Organic Functional Groups - you must know these • They will show up time and time again in Biochemistry • Note that the charge state of some of the groups above will differ in different environments/conditions (e.g., COOH and COO-; NH 3 and NH 4 +) Key Organic Functional Groups. cont
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6 Chemical Evolution • Many enzymes catalyze hydrolysis and condensation reactions • In prebiotic times, clay may have provided the environment for catalytic reactions (zeolites are used as chemical catalytic environments today) • In particular, the condensation reaction has been very useful throughout evolution for increasing biological complexity • Of course, the hydrolysis carries out the reverse reaction, leading to a loss in biological complexity • Complementarity allows for (self) replication through templating (e.g., COO-…NH 4 +) • Base complementarity in DNA
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7 • Vesicles (fluid-filled sacs) are thought to be the precursors to cells • These entities would have had the ability to shield self-replicating
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This note was uploaded on 10/05/2010 for the course BCHS BCHS 3304 taught by Professor Legge during the Spring '09 term at University of Houston.

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Review_Exam1 - Living organisms operate within the same...

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