LAB: Cellular Energy: ATP as “CASH”



LAB: Cellular Energy: ATP as “CASH” Name __________________________

Date ____________________Per.___

INTRODUCTION: Is energy free to slosh around inside living cells? The answer is NO. Energy exists as chemical energy, the energy contained within the bonds of molecules. Molecules come into a cell in various forms and all of them are broken down, releasing their chemical energy. This energy is captured and held in the bonds of a special molecule known as ATP. ATP (Adenosine TriPhosphate) is like cellular “cash in the bank”. The cell will break ATP down and get the energy out to “spend” when it needs to do cellular work (such as active transport). When ATP is broken down, a phosphate group is lost (lost as Pi) and ADP (Adenosine DiPhosphate) results. ADP can be quickly converted back to ATP, as chemical energy is available in the cell. The constraint conversion of ATP to ADP and back to ATP is much like a checking account that holds deposits temporarily and is subject to constant withdrawal. Enzymes control these reactions inside of the cell.

OBJECTIVES:

• Use paper model molecules to make a molecule of ATP and ADP

• Determine similarities and differences between an ATP and an ADP molecule

• Discover how ATP releases energy when changed to ADP

PROCEDURES:

1. ATP is made of smaller molecules or subunits: adenine, ribose and 3 phosphates.

EXAMINE the structural formulas below:

2. Answer questions 1 through 7 on your study sheet page.

3. An ATP molecule is made up of one adenine, one ribose and three phosphate groups (phosphoric acid

groups). COLOR the adenine - BLUE. Ribose - RED, and Phosphoric acid – GREEN.

CUT out the models of these structures, cutting on solid lines ONLY to begin with.

4. Attempt to join adenine and ribose. Then cut around dotted lines such that the adenine, ribose and all

three phosphate groups can be joined. The molecule will look somewhat like the letter, L. Glue this ATP

molecule onto your typing paper. Glue the water molecules and use arrows to show where the water

molecules are released. Note that the “bonds” between 2 phosphate groups are modeled with larger tabs.

These are high-energy bonds Label them by inserting a high sign (~) between the P’s.

Label molecule: ATP--P P P + ____H20

5. Attempt to make an ADP by joining the adenine and ribose. Then cut around dotted lines such that the

adenine, ribose and 2 phosphate groups can be joined. The molecule will look somewhat like the letter, L.

Glue this ADP molecule onto your typing paper. Glue the extra P and water molecules and show where the

water molecules are released. Label the molecule: ADP + P + E

(ADP + P + E ATP -- P P P + _____H20 OVER

Two bonds

6. Answer questions 8 – 12

two bonds

7. Glucose is the major source of chemical energy for the cell.

Its molecular formula is C6H12O6 . Thus there are 24 chemical bonds

in the molecule. When glucose is broken down, 2 molecules of pyruvic acid result.

EXAMINE the structural formula of pyruvic acid:

8. Answer the remaining questions on you study sheet.

9. Paste MODEL ON ANSWER SHEET / Label the molecule: ATP --P P P + ____H20

Label the molecule: ADP + P + E

(ADP + P + E ATP--P P P + _____H20

LAB: Cellular Energy: ATP as “CASH” Name ______________________

Date______________ Per.______

OBJECTIVES:

• Use paper model molecules to make a molecule of ATP and ADP

• Determine similarities and differences between an ATP and an ADP molecule

• Discover how ATP releases energy when changed to ADP

1. Which subunit of ATP seems to be the largest molecule? _________________________________________

2. Which elements are represented in this molecules? ______________________________________________

3. What is the molecular formula for ribose? _____________________________________________________

4. Is ribose a carbohydrate? ________ How do you know? __________________________________________

5. Write the molecular formula for phosphoric acid (phosphate). _____________________________________

6. Which element is found in adenine but NOT in ribose?__________________________________________

7. Which element is found in phosphate but NOT in adenine or ribose? _______________________________

8. Which molecular groups had to be removed with scissors to connect the parts of ATP? _________________

9. What is the process called when this molecule is removed and a ATP is formed ? ______________________

ATTACH YOUR ATP MOLECULE ON THE TYPING PAPER: Label: ATP P P P + _____H2O

ATTACH YOUR ADP MOLECULE ON THE SAME TYPING PAPER: Label: ADP + P + E + ____H2O

Put the formulas together: ADP + P + E (( ATP P P P + _____H2O

10. What does this formula represent? __________________________________________________________

11. How many high energy bonds are found in an ATP molecule? ___________________________________

12. When the cell needs available energy to do work, it breaks one high energy bond. Which molecule is left

after this break occurs?

______________________________________

13. How many high-energy bonds remain in an ADP molecule? ______________________________________

14. The molecular formula of one glucose is C6 H12 O6. What is the molecular formula for one pyruvic acid

molecule?

_________________________

15. Two pyruvic acid molecules result from the cleavage of one glucose molecule. How many chemical bonds

are represented by two pyruvic acid molecules?

_________________________

16. Which atoms have been lost when glucose is cut into pyruvic acid? ____________________

over(

17. When bond energy is lost from glucose, it is used to turn one ADP molecule into one _________ molecule.

18. What will the cell do at some later time with this ATP? _______________________________________

19. Which molecule represents more “cash in the bank” to a cell, ADP or ATP _____________

Why? _______________________________________________________________________________

20. Pi represents inorganic phosphate. This is lost when ATP becomes ADP. Why is this molecular group

referred to as inorganic?

______________________________________________________________

21. Why is ATP use in the cell analogous to the use of currency in society? Be specific.

_______________________________________________________________________________________

PASTE MODELS BELOW: Label the molecule: ATP P P P + ____H20

Label the molecule: ADP + P + E

(ADP + P + E ATP P P P + _____H20

• Conclusion: Why paper model molecules to make a molecule of ATP and ADP .What are the similarities and differences between an ATP & ADP molecule How does ATP releases energy when changed to ADP? STAPLE

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