Unit 2: The Living Cell
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Study Guide
Chapter 6
Energy and Life
Review
Energy is the ability to do
and exists in two states:
energy and
energy.
Energy
flows
from the sun to photosynthetic organisms which store surplus energy in
as
energy.
Living systems transfer energy in
reactions which follow the
laws
of
, or energy change.
The
law of thermodynamics (
of energy) states that energy can neither be
nor
, only
changed
from one form to another.
The
law of
thermodynamics
states that
in a system always increases as the result of the conversion of
energy into random molecular motion (heat).
Most chemical
reactions
are
: they release energy and can proceed spontaneously, but may require a
to lower the
energy
to initiate the process.
Proteins that act as catalysts are called
and act by binding reactants of a
reaction
to its
site,
lowering the
energy of the reaction.
An
enzyme
can be regulated by altering its
in response to the binding of an
or
signal molecule.
Enzymes must be in the proper 3-dimensional
(
conformation
) to be active. Factors that affect enzyme function include
and pH, and so most enzymes have an
optimal
temperature and pH range.
triphosphate
(ATP) is the main energy currency of the cell. Energy from
and aerobic
is stored in this molecule, which can be
hydrolyzed
for cellular work, releasing
in the process.
Energy from
is used to power many of the cell's
activities.
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Feb 4, 2010
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