Biology 1002B Lecture Notes - Lecture 4: Exergonic Reaction, Enzyme, Telomerase Reverse Transcriptase

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Published on 15 Apr 2013
School
Western University
Department
Biology
Course
Biology 1002B
Professor
Lecture 4: Energy and Enzymes
January 16, 2013
2nd law disorder of system + surrounding increase
Cells are highly ordered, proteins are also order
o Cells are open system so there’s exchange of energy between the cell (system) and the
surrounding. This allows the cell to bring in large amount of energy to maintain order
o Heat increase the disorder of the surrounding
Free energy
o Delta G = Delta H T X delta S
o Delta G = free energy (endergonic (+) or exergonic (-)
o Delta H = enthalpy (can be endothermic (+) or exothermic (-)
o Delta S = entropy (more ordered (+) or less disorder (-)
o Reaction tend to be spontaneous (- delta G) (exergonic) when… the potential energy of
product is higher than the potential energy of reactants
Also spontaneous when its more disordered, when entropy is high
Contributions of enthalpy and entropy
o Fermentation of glucose to ethanol
o C6H1206(s) -> 2C5H5OH (l) + CO2 (g)
o It is spontaneous, it has a delta G of -218 KJ/mol
o It is exothermic, delta H is 82 KJ/mol
o T detla S is 136 KJ/mol
o E.g. melting of ice
H20 (s) -> H20 (l)
Delta G = -225 KJ/mol
This is a endothermic process, delta H is + 95KJ/mol
What drives this is massive disorder, it is entropy driven, T delta S = 320 KJ/mol
Enzymes
o They have massive impact on speeding up the process, it can speed it up about 10^12
10^20 times faster than regular natural process
o Why does life need enzymes?
Using enzymes to not increasing the temperature, to achieve the same speed of
the reaction we needed in our body
o What enzymes do and don’t do
A -> B -> C
Delta G <0 delta G >0 (need energy)
Enzymes do not provide energy for the process, cannot do anything if there is
no energy supporting them
Exergonic reaction energy profile
o Transition state:
o Activation energy: amount of energy required to reach the transition state (Ea, barrier)
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Document Summary

2nd law disorder of system + surrounding increase. Cells are highly ordered, proteins are also order: cells are open system so there"s exchange of energy between the cell (system) and the surrounding. This allows the cell to bring in large amount of energy to maintain order: heat increase the disorder of the surrounding. Also spontaneous when its more disordered, when entropy is high. Contributions of enthalpy and entropy: fermentation of glucose to ethanol, c6h1206(s) -> 2c5h5oh (l) + co2 (g, t detla s is 136 kj/mol, e. g. melting of ice. It is spontaneous, it has a delta g of -218 kj/mol. It is exothermic, delta h is 82 kj/mol. This is a endothermic process, delta h is + 95kj/mol. What drives this is massive disorder, it is entropy driven, t delta s = 320 kj/mol. Enzymes: they have massive impact on speeding up the process, it can speed it up about 10^12 .

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