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Chapter 8

BIL 150 Chapter Notes - Chapter 8: Catabolism, Emergence, Chemical Energy

Course Code
BIL 150
Gaines Michael

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Chapter 8 – An Introduction to Metabolism (141-151)
Metabolism – the totality of an organism’s chemical reactions
oMetabolism is an emergent property of life that arises from orderly
interactions between molecules
Metabolic Pathways – begins with a specific molecule, which is then
altered in a series of defined steps, resulting in a certain product
oEach step of the pathway is catalyzed by a specific enzyme
oSome metabolic pathways release energy by breaking down
complex molecules into simpler compounds, and these pathways
are called catabolic pathways
Cellular respiration is a catabolic pathway, in which the sugar
glucose and other organic fuels are broken down in the
presence of oxygen to carbon dioxide and water (pathways
can have more than one starting molecule and/or product)
During a catabolic reaction, some bonds are broken and
others formed, released energy and resulting in lower-
energy breakdown products
oAnabolic pathways on the other hand consume energy to build
complicated molecules from simples ones (sometimes called
biosynthetic pathways)
Synthesis of a protein from amino acids
oEnergy released from the downhill reactions of catabolic pathways
can be stored and then used to drive the uphill reactions of the
anabolic pathways
Forms of energy
oEnergy is the capacity to cause change
oEnergy associated with the relative motion of objects is called
kinetic energy
Moving objects can perform work by imparting motion to
other matter
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oThermal energy is kinetic energy associated with the random
movement of atoms or molecules
Thermal energy in transfer from one object to another is
called heat
oPotential energy is energy that matter possesses because of its
location or structure
Example: water behind a dam possess energy because of its
altitude above sea level, molecules posses energy because
of the arrangement of electrons in the bonds between their
oChemical energy is a term used to refer to the potential energy
available for release in a chemical reaction
Thermodynamics is the study of the energy transformations that occur in
a collection of matter
o1st law of thermodynamics: the energy of the universe is constant
Energy can be transferred and transformed, but it cannot be
created or destroyed (principle of conservation of energy)
o2nd law of thermodynamics: every energy transfer or
transformation increases the entropy of the universe
Entropy is a measure of disorder, or randomness
Although order can increase locally, there is an unstoppable
trend toward randomization of the universe in whole
A spontaneous process is one that leads itself to an
increase in entropy and can proceed without requiring an
input of energy
Free energy is the portion of a system’s energy that can perform work
when temperature and pressure are uniform throughout the system, as in
a living cell
oThe change in free energy can be calculated by ΔG = ΔH - T ΔS
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