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Energy in the Bonds of ATP
Background:
Energy is the ability to do work. Potential energy is the energy of position or stored energy, and it can be converted
into kinetic energy. Kinetic energy is the energy of motion. Chemical bond energy, a type of potential energy, is the
energy stored in the bonds of molecular substances. In cellular respiration, cells produce chemical bond energy.
Imagine that you are standing on the second floor of a building. You have potential energy due to your position – and
the taller the building, the greater the potential energy you would have. You can convert it to kinetic energy all at once
by jumping to the floor below, or you can release it a little at a time by walking down the stairs.
The problem is that the release of the chemical bond energy of carbohydrates, such as glucose, in a
cell must be done in a manner that does not destroy the cell during the process. In cells, potential
energy in the chemical bonds of food is transferred to the bonds of a substance called “adenosine
triphosphate” (ATP).
Adenosine Triphosphate (ATP): Adenosine triphosphate is the most common energy-storing
molecule in the cell. ATP is constructed from a nucleotide called adenine and a sugar called ribose. Together, the
adenine and ribose are called adenosine. Adenosine triphosphate is called triphosphate because of the three
phosphates attached to the adenine and ribose.
Adenine + Ribose Sugar + 3 Phosphates =
Two other molecules in the cell are related to ATP:
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Adenosine diphosphate (ADP) has two phosphate groups
attached to it: A-P~P.
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Adenosine monophosphate (AMP) has a single phosphate
group: A-P.
When organisms need energy, they split the third phosphate group
from ATP to form ADP and a single phosphate. The energy from that is
used to power many cellular processes. This reaction is an exergonic
reaction meaning that it happens spontaneously without the cell
needing to initiate this reaction.
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Materials:
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1 large wooden block
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3 rubber bands
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3 small wooden blocks
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1 meter stick
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4 safety goggles
Procedure:
1. If not labeled, label the large wooden block with an A (adenosine).
2. If not labeled, label each of the smaller three wooden blocks with a P (phosphate group).
3. Use three rubber bands to represent the chemical bonds and holding the phosphates to the adenosine molecule.
The first rubber band goes around the adenosine block and one phosphate group. The second goes around the
adenosine and two phosphate groups. The third goes around the adenosine and three phosphate groups.
4. Cut the rubber bands with scissors to simulate the breaking of the bonds. Start with the band encircling all three
phosphate groups. Then cut the one circling two phosphate groups. Then finish with one circling one phosphate
group.
5. Measure the distances in centimeters the rubber bands traveled, which represent the amounts of energy in the
molecule. Record these results in cm on your results sheet.
Safety Note: The trajectory of a rubber band can be totally unpredictable. Be prepared!
Safety goggles are to remain on until I say you may remove them.
Data and Analysis Questions
Distance(cm) Traveled by Each Rubberband
Band around 3 Phosphate Groups
Band around 2 Phosphate Groups
Band around 1 Phosphate Group
1. Annotate each chart to indicate which rubber band had:
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The most kinetic energy
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The least kinetic energy
The most potential energy
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The least potential energy
Potential Energy
Band around 3 Phosphate Groups
Band around 2 Phosphate Groups
Band around 1 Phosphate Group
Kinetic Energy
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2. Based on your results above, which bond has the greater amount of potential energy, the bond between the
first and second phosphate or the second and third phosphate? Which has the greater amount of kinetic
energy?
Most Potential Energy
Most Kinetic Energy
3. Based on your experimental results, which molecule would provide more energy to the cell, ATP or ADP? Be
sure to connect your claim directly to the data you collected in your experiment.
4. Explain in terms of potential and kinetic energy why an athlete needs to eat more than a couch potato.
5. Do plants need ATP? Why or Why not?
6. The graphic shown demonstrates how your body moves your muscles on a cellular level. Explain what energy
molecule your body most likely uses for this process.