All molecules are made up of atoms which are
joined together by bonds. The bonds which join
atoms contain energy. Because different atoms
have different properties, the bonds between
different atoms will vary in their strength and
amount of energy.
The cells in your body
function by manipulating and rearranging molecules
to form new bonds or break old ones, in a process
called metabolism. By controlling the formation
and breakage of particular chemical bonds your
cell can control the energy present in the bonds.
Basically, everything that happens in your body
is the result of these controlled chemical
reactions that are occurring in your cells.
Some chemical reactions release energy when
they occur. Others require energy. Your cell is
able to use chemical reactions that release energy
in order to achieve desired reactions that consume
energy. It accomplishes this through an
intermediary molecule called ATP. ATP is a
molecule that contains three phosphates, and the
bond between two of the phosphates contains a lot
of energy. Your cells use the energy released
from an energy-releasing chemical reaction to
produce ATP (by joining the molecule ADP with
another phosphate molecule). By coupling these
reactions the cell has effectively captured some
energy in the bonds of the ATP. (This is just one
way of producing ATP, called substrate-level
phosphorylation. But there are other ways that
cells can produce ATP too-- for example, through
aerobic respiration or photosynthesis!). Later,
when the cell needs energy to perform another
chemical reaction, it can use the energy released
by breaking the phosphate bond in ATP (again
separating the ADP and phosphate molecules) to
make the reaction go.
Some organic molecules
contain a lot more energy in their bonds, due to
the types of bonds they possess. This makes them
rich stores of chemical energy. Keep in mind,
though, that it's not just the energy in the bonds
that is important to your body! The bonds must
also be of the right type for your body to use in
its chemical reactions!
If you want to know
why, exactly, some bonds contain more energy than
others, that is something that unfortunately I do
not understand. I hope a chemist or a physicist
can help explain that to you!
It takes lots of energy to make some organic
chemicals.Some of this energy is lost as heat when
the organic chemicals are synthesized, and some of
this energy is stored in the organic chemicals.
When these organic chemicals are broken down or
metabolized into smaller organic chemicals, some
of their stored energy is released in forms that
can be used by the cells.
A mechanical analogy
is that you can roll a stone up a hill, which
needs energy, and puts the stone in a position of
higher energy. Then you can let the stone roll
down the hill, where it can do work along the way,
such as by knocking things over.
chemical that has a lot of chemical energy is ATP
[Adenosine TriPhosphate]. When it loses a
phosphate group and becomes ADP [Adenosine
DiPhosphate], it releases a lot of energy that can
be used to create new chemical bonds.
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