unit+1+ +introductory+lecture
TRANSCRIPT
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UNIT 1: Introduction - Chemical and PhysicalFoundations of Biochemistry
Learning goals : to understand about Roles of small and large biomolecules
Energy transformation in living organisms
Regulation of metabolism and catalysis
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Albert Lehninger (1917-1986)Citric acid cycle occurs in mitochondria
Mechanism of oxidative phosphorylation
Mitochondrial structure and function
Bioenergetics
Author of classic textbooks :
B iochemistry (1970-1983)The Mitochondrion (1964)
B ioenergetics (1965 -1974)
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T he Interface Between Biology and
Chemistry
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Chemistry within the Cell
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Biochemistry : Unique Role of Carbon
Biomolecules are carbon-basedElements H, O, N, P, S are also commonMetal ions (e.g. K +, Na +, Ca ++, Mg++, Zn++, Fe ++) playimportant roles in metabolismTogether, about 30 elements are essential for life
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Biological Molecules T ypically HaveSeveral Functional Groups
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Structure of Biological Molecules isImportant
T he function of molecules strongly depend on three-dimensional structure
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Stereoisomers have DifferentBiological Properties
Cis and trans isomers have also different physical andchemical properties
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Optical Isomers have Different BiologicalProperties
Enantiomers have identical physical properties (except regardto polarized light ) and react identically with achiral reagents.
Diastereomers have distinct chemical and biologicalproperties because bio-molecules are themselves chiral.
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Interactions between Bio-molecules areSpecific
Macromolecules have unique binding pockets
Only certain molecules fit in well and can bind
Binding of chiral bio-molecules is stereospecific
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T he Molecular Logic of Life
We look at the chemistry that is behind :
Accelerating reactions
Organization of metabolism and signaling
Storage and transfer of information
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How to Speed Reactions Up?
Higher temperatures
Stability of macromolecules is limiting
Higher concentration of reactants
Costly as more valuable starting material isneeded
Lower activation barrier by catalysis
Universally used by living organismsChange the reaction by coupling to a fast one
Universally used by living organisms
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Unfavorable and Favorable
ReactionsSynthesis of complex molecules and many other metabolicreactions requires energy (endergonic )
A reaction might be thermodynamically unfavorable (( Gr
> 0)
Creating order requires work and energy Metabolic reaction might have too high energy barrier (( G > 0)
Metabolite is kinetically stable
Breakdown of some metabolites releases significant amount of energy (exergonic )
Such metabolites (ATP, NADH, NADPH) can be synthesizes using the energyfrom sunlight and fuels
Their cellular concentration is far higher than their equilibriumconcentration.
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Catalysis
A catalyst is a compound that increases the rate of achemical reaction
Catalysts lower the activation free energy ( G
Catalysts does not alter ( G
Catalysis offers : Acceleration under mild conditions High specificity Possibility for regulation
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Energy Coupling
Chemical coupling of exergonic and endergonicreactions allows otherwise unfavorable reactions toproceed
Biology often links the hydrolysis of the high-energymolecule AT P directly with the metabolite that needs
activation thus coupling the two reactions.
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AT P: Chemical Currency of Energy
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Metabolic Pathwayproduces energy or valuable materials
Signal Transduction Pathwaytransmits information
Series of Related ReactionsForms a Pathway
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Example of a negative regulation :Product of enzyme 5 inhibits enzyme 1
Pa thw ays Are Contr o lled in Order toRegul a te Level s of M et a b o lite s
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Chapter 1: Summary
T he main learning goals were :To relate structure and function of the cellTo realize that the structure of biomoleculesoften gives them specific functionsTo grasp principles of bioenergetics