Biolo1100
Chapter 5
Energy and Life
Energy exists in two states:
potential
energy and
kinetic
energy
.
Energy
flows
from the sun to
producers
and
consumers
in most ecosystems.
Living systems transfer energy in
chemical
reactions which follow the
laws
of
thermodynamics
, or energy change.
First
law of thermodynamics
Second
law of thermodynamics
Chemical
reactions
can be
endergonic
or
exergonic
, but may require a
catalyst
to speed up the
process
.
Proteins that act as catalysts are called
enzymes
and act by binding reactants of a
reaction
to its
active
site
, lowering the
activation
energy of the reaction.
Factors that affect enzyme function include
temperature
and
pH
, and enzymes need an
optimal
range of these conditions.
Adenosine
triphosphate
(ATP) is the main energy currency of the cell.
Energy from
ATP
is used to power many of the cell's
activities
.