Biology 1202B Lecture Notes - Dehydration Reaction, Anabolism, Exergonic Reaction

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18 Jan 2013
Department
Bioenergetics, Enzymes & ATP
Bioenergetics
The study of energy in living systems (environments) and the organisms (plants and
animals) that utilize it
Potential Energy
Energy that matter occupies because of its location, arrangement, or position --> energy
of position
o Water behind a dam
o Chemical energy (gas)
Kinetic Energy
Energy in the process of doing work --> energy of motion
o Heat
o Light energy
Three systems…
o Isolated system - does not exchange matter or energy with its surroundings
o
Thermos bottom
o Closed system - exchanges energy with its surroundings
o
Planet Earth
o Open system - exchanges both energy and mater with its surroundings
o
Ecosystem, cell, plant, animals
First Law of Thermodynamics
Energy cannot be created or destroyed but only converted to other forms
This means that the amount of energy in the universe is constant
Second Law of Thermodynamics
All energy transformation are inefficient because every reaction results in an increase in
entropy and the loss of usable energy as heat
o Entropy - the amount of disorder in a system
Biological Work…Why?
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Biosynthesis
o Nucleotides -> DNA/RNA
o Amino acids -> Proteins
o CO2+H2O -> CHO (glucose)
Transport
o Passive (spontaneous) doe snot require energy
o Active requires energy
Biological Work
Free energy - the part of a system's total energy that can perform work when the
temperature is uniform as in a living cell
o Represented by G
o
Two components…
H (system's total energy)
S (the entropy of the system)
G=H-TS
The change in free energy in a system changing from one state to another is symbolized
by dG
o dG = Gf - Gi
o dG = dH - TdS
o Change in free energy between reactants and products
Entropy
Entropy measures energy that is longer available to perform useful work within the
current environment
Can also be understood as the "quality" of heat flowing between two bodies
One of the ideas involved in the concept is that nature tends from order to disorder in
isolated systems
Endergonic Reactions
dG > 0
Chemical reactions that requires a net input of energy
o Photosynthesis - CO2 + H2O -> C6H12O6 + O2
Exergonic Reactions
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