In Search of Energy

ATP consists of a base, in this case adenine (red), a ribose (magenta) and a phosphate chain (blue).[pic 1]

ATP works by losing the endmost phosphate group when instructed to do so by an enzyme. This reaction releases a lot of energy, which the organism can then use to build proteins, contact muscles, etc. The reaction product is adenosine diphosphate (ADP), and the phosphate group either ends up as orthophosphate (HPO4) or attached to another molecule (e.g. an alcohol). Even more energy can be extracted by removing a second phosphate group to produce adenosine monophosphate (AMP).

[pic 2]

When the organism is resting and energy is not immediately needed, the reverse reaction takes place and the phosphate group is reattached to the molecule using energy obtained from food or sunlight. Thus the ATP molecule acts as a chemical 'battery', storing energy when it is not needed, but able to release it instantly when the organism requires it.

3. Note that ATP is a nucleic acid. Think about what you know about the structure of nucleic acids such as DNA. Remember that the basic structure of each nucleotide consists of a nitrogenous base, a sugar and a phosphate group. The building block of ATP takes this same structure. List the sugar and the base found in molecules of ATP in the space below.

Sugar: ribose                     Base: adenine

4.Draw a diagram of the ATP molecule. Each of the three components of the molecule should be a different color and each part should be clearly labeled.

5. Where is the energy located in the ATP molecule? Indicate on your drawing in Step 4 where the energy is being stored.

The energy is located in the last group of the phosphate chain.

6. Review the equation for the breakdown of ATP and the release of energy shown below.

 ATP  + H2O  à ADP  +  Pi  + energy

7. What do we call the type of chemical reaction that occurs in #6? Explain how the name of this type of reaction relates to a key resource other than food.

 Hydrolysis; water is the key resource of the body. This means that water is being turned into the ATP.

8. What is ADP and how is it generated?

 Adenosine Diphosphate ADP is generated when the ATP molecule attempts to create energy and loses a phosphate group resulting in an ADP molecule. You can remember this by Adenosine TRIphosphate(3 phosphate groups) and Adenosine DIphosphate(2 phosphate groups).

9. We have said before that ATP is recycled. What do you think is the simple equation for reforming ATP?

The equation for reforming ATP is ADP + Pi = ATP + H2O.

 10. Name the process human cells use to generate more ATP. Where in the cell does this process occur?

It occurs in mitochondria by cellular respiration, which is the process of oxidizing food molecules into carbon dioxide and water.

11. The general chemical equation for the ATP generating process in cells is listed below. If necessary, research the identity of each item. Write the common name underneath each reactant (what goes in to the reaction?) and product (what comes out of the reaction?).

C6H12O6  +  6O2  à  6CO2  + 6H2O  + ATP

glucose + oxygen      oxygen + water + adenosine triphosphate

12. The process of cellular respiration shown in #11 produces ATP by rejoining a phosphate group with the ADP molecule. Where do you get the C6H12O6 and O2 that is required for this process?

 We get C6H12O6 from eating (it's glucose) and we get O2 from breathing (it's oxygen).

 13.  What happens to the CO2 that is produced in the reaction?

 The CO2 is carbon dioxide in which we breathe out.

 14.  Which types of cells in the body would you expect to require the most ATP? Support your answers with evidence.

Your muscle cells require massive amounts of ATP. They are responsible for all of your movements. Most of the energy burned during your day is through movement of your body by skeletal muscles.

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H    How has a process in nature been used as a medical intervention?

For the first time ever, researchers at the University of Bristol have been able to directly measure energy levels inside living heart cells, in real time, using the chemical that causes fireflies to light up.

What does the level of ATP tell scientists about the functioning of the heart.

The breakthrough presented by this technique could be of benefit in heart diseases where mitochondria cannot make enough ATP. When that happens the heart does not have enough energy to perform its function of pumping blood efficiently which can result in a heart attack.

What are potential applications of this research? How can this type of test help patients?

Being able to see exactly what's going on in heart cells will be of great benefit to understanding heart disease. The researchers made use of a protein called luciferase, which is normally found in the tails of firefly and is what causes them to light up. Using molecular biological techniques, they transferred modified forms of the luciferase DNA into heart cells – the cells could then make their own luciferase, and the modifications enabled the luciferase to be produced inside the mitochondria.

1. Based on what you learned in PBS, what are three foods that would be considered good energy sources? Explain your choices.

Almonds, like many nuts, are one of the best plant sources of protein. Protein will help regulate your blood sugar and keep your energy level stable throughout the day. Oats contain the energizing and stress-lowering B vitamin family, which helps transform carbs into usable energy. Water, without water, your body cannot generate energy.

  2. Name three specific body processes that require energy in the form of ATP.

- -Muscle contractions    -Nerve impulses    -Active transport in the cell membrane