This is a great question. It's more of a
biochemical question, and I'm not a biochemist,
but I'll do my best. We biologists often talk
about energy being contained in bonds and released
when the bonds are broken. What really going on
is that some bonds are broken and other bonds are
Think about it this way. Suppose someone tosses
your favorite candy toward you. You grab it
because you are attracted to it. Atoms are
attracted to each other by their opposite charges.
Remember that electrons have a negative charge and
the protons in the nucleus have positive charges.
So the electrons and protons are attracted to
each other. They attract each other in the same
atom, but also between atoms.
Atoms form molecules with bonds between the
atoms when their opposite particles are attracted
to each other. (Particles with the same charges
repel each other.)
You're not going to just let go of the candy
unless you're offered something better. Now
suppose that you are shown a twenty dollar bill
but can only take it with the same hand that is
holding the candy. You would probably drop the
candy and grab the 20 because you are more
attracted to it.
Stable molecules don't fall apart on their own,
but adding a bit of energy may break them apart
and allow them to make even stronger bonds. The
greater the difference between the weaker bond
that is broken and the stronger bond that forms,
the more energy is released to do work. Think of
this as just dropping one candy for a slightly
better one, but throwing the candy if you got to
grab a $100 bill.
When we break down food, such as glucose, we
break the weak bonds inside the glucose molecule
and the atoms form stronger bonds in other
molecules. It takes a bit of activation
energy to break down the glucose. We'll get a lot
of energy out (about 16 times the activation
energy) by the time we have broken the glucose
down through many steps to get all the atoms in
the glucose into H2O and CO2
ATP (an adenosine with three phosphates)
makes a good energy carrier because it is so
unstable. When one phosphate breaks off, a lot of
energy is available for doing work.
I hope this helps. You may want to study
biochemistry to understand this sort of things
Thanks for asking,
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