Bioenergetic Flashcards
- Energy can be thought of as the
capacity to cause specific chemical or physical changes
There is a massive, unidirectional flow of energy from
the source in the fusion reactions in the sun to the sink, the environment
The flow begins with the
production of high-energy, reduced compounds by photosynthesis
Oxidation is
the removal of electrons from a substance, usually hydrogen atoms (H+ plus one electron).
Oxidation
reactions release energy
Reduction, the addition of electrons
s to a substance through addition of
hydrogen atoms (and a loss of oxygen atoms), requires an input of energy
Energy for Cells
-Living cells are inherently unstable.
-Constant flow of energy prevents them from
becoming disorganized.
-Cells obtains energy mainly by the oxidation of
bio-molecules (e- transferred from 1 molecule
to another and in doing so they lose energy)
-This energy captured by cells & used to
maintain highly organized cellular structure and
function
Three of the most important variables
are constant during biological reactions.
the same temperature, pressure, and
volume during the entire reaction.
Bioenergetics
s the study of the transformation of energy in living organism
Changes in free energy provide
a measure of the energetic feasibility of a chemical reaction and can, therefore, allow prediction of whether a reaction or process can take place.
Bioenergetics concerns only the
initial and final energy states of reaction components, not the mechanism or how much time is needed for the chemical change to take place (the rate).
Energy is defined as
s the capacity to do work which is the product of a given force acting through a given distance
The first law of thermodynamics
in every physical or chemical change, the total amount of energy in the universe remains constant
Total energy stored within a system is
internal energy, or E
E is the change
in internal energy that occurs during some process.
Enthalpy, H
The heat energy change [ΔH] that takes place when reactants go to products
heat is absorbed during the reaction,
[ΔH] is positive
Thermodynamic spontaneity is a measure of
whether or not a reaction or process can occur.
heat is released
[ΔH] is negative
Whether or not a reaction can proceed can be
measured by
changes in entropy or free energy
Entropy (S) is a measure
of randomness or disorder
the change in entropy
a change in degree of randomness or
disorder
Entropy increases when
a system becomes less
ordered
– Entropy decreases
when a system becomes
more ordered
free energy (G)
A measure of spontaneity for a system alone
Exergonic reactions are
energy-yielding, and occur spontaneously (G < 0)
Endergonic reactions are
energy-requiring and do not occur spontaneously under the conditions specified (G > 0)
Cells maintain a steady state (homeostasis)
in which reactants, products, and intermediates are kept at levels far from equilibrium
