Chapter 8 (Notes) Flashcards
Metabolism
is the totality of an organism’s chemical reactions
Metabolism is an emergent property of life that arises from interactions between
molecules within the cells.
It is both the breaking down and building up of things.
A metabolic pathway
begins with a specific molecule and ends with a product.
Each step is catalyzed by a specific enzyme.
Catabolic pathways
release energy by breaking down complex molecules into simpler compounds.
Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a
pathway of catabolism.
Anabolic pathways
consume energy to build complex molecules from simpler ones
The synthesis of protein from amino acids is an example of
anabolism
Bioenergetics is the study of
how organisms manage their energy resources.
Catabolic Pathways
- breaking down (molecules)
- release energy
- spontaneous (just happens)
- exergonic
- Delta G=negative (the triangle G)
-on a graph:
it starts with high energy (reactants), then it ends up with low energy (products).
Anabolic Pathways
- building up
- needs/requires energy
- non-spontaneous
- endergonic
- Delta G=positive (the triangle G)
-on a graph:
it starts with low energy (reactants), then it ends up with high energy (products).
Energy is the
capacity to cause change.
Energy exists in various forms, some of which can perform work.
Kinetic energy is energy associated with
motion
Heat (thermal energy) is
kinetic energy associated with random movement of atoms or molecules
Potential energy is energy that
matter possesses because of its location or structure
Chemical energy is
potential energy available for release in a chemical reaction.
Energy can be converted from
one form to another.
Some energy is ALWAYS lost as heat when conversion occurs.
Thermodynamics is
the study of energy transformations (and how it moves around).
An isolated system, such as that approximated by liquid in a thermos, is
isolated from its surroundings.
the liquid is completely closed off
In an open system, energy and matter can be
transferred between the system and its surroundings.
Organisms are
open systems.
They are constantly bringing in energy from the outside and releasing energy from the inside
According to the First Law of Thermodynamics,
the energy of the universe is constant.
Energy can be transferred and transformed, but it cannot be created or destroyed.
((Energy is constant in the Universe))
The first law is also called the principle of conservation of energy.
During every energy transfer or transformation, some energy is
unusable, and is often lost as heat.
According to the Second Law of Thermodynamics,
every energy transfer or transformation increases the entropy (disorder) of the universe.
Entropy will always increase in energy transfer.
Living cells unavoidably convert organized forms
of energy to heat.
Spontaneous processes occur
without energy input; they can happen quickly or slowly.
For a process to occur without energy input, it must
increase the entropy of the universe.
Cells create ordered structures from
less ordered materials.
Organisms also replace ordered forms of matter and energy with
less ordered forms.
Energy flows into an ecosystem in the form of
light and exits in the form of heat.
The evolution of more complex organisms dow not violate the
second law of thermodynamics.
Entropy (disorder) may decrease in an organism, but
the universe’s total entropy increases.
Biologists want to know which reactions occur spontaneously and which require input of energy.
To do so, they need to determine energy changes that occur in chemical reactions.
A living system’s free energy is
energy that can do work when temperature and pressure are uniform, as in a living cell.
The change in free energy (delta G) during a process is related to the change in
enthalpy, or change in total energy (delta H), change in entropy (delta S), and temperature in Kelvin (T).
(Delta G)=(Delta H) - T (Delta S)
Only processes with a negative delta G are
spontaneous.
Spontaneous processess can be harnessed to
perform work.
Free energy is a measure of a
system’s instability, its tendency to change to a more stable state.
During a spontaneous change,
free energy decreases and the stability of a system increases.
Equilibrium is a state of
maximum stability.
A process is spontaneous and can perform work only when
it is moving toward equilibrium.
The concept of free energy can be applied to the
chemistry of life’s processes.
An exergonic reaction
proceeds with a net release of free energy and is spontaneous.
delta G is negative.
This is also catabolic.
It starts with high energy (reactants), then ends up with low energy (products).
((what it looks like on a graph))
An endergonic reaction
absorbs free energy from its surroundings and is nonspontaneous.
delta G is positive.
This is also anabolic.
It starts with low energy (reactants), then ends up with high energy (products).
((what it looks like on a graph))
Reactions in a closed system eventually reach
equilibrium and then do no work.
Cells are not in equilibrium; they are
open systems experiencing a constant flow of materials.