Video Transcript
ATP has many properties that make it well suited to carry out its functions. Which of the following is not a property of ATP? (A) It is a relatively small molecule that can easily diffuse to different parts of a
cell. (B) It is water-soluble, so reactions can happen in aqueous environments. (C) It is an insoluble molecule that can pass easily through the phospholipid
bilayer. (D) It releases energy in small, manageable quantities. (E) It is constantly being broken down and regenerated.
We get a lot of our energy from the food we eat in the form of the sugar molecule
glucose. This glucose has energy stored in its chemical bonds. And this energy can be extracted by a process called cellular respiration to convert
glucose into carbon dioxide and water. During this process, ATP is produced. ATP, or adenosine triphosphate, stores this energy in the form of high-energy
phosphate bonds. The three phosphate groups are linked to one another by high-energy bonds that can be
broken to release energy. When energy is needed, the covalent bond between the second and third phosphate
groups of ATP is broken and released for numerous biological processes in the
cell.
Now let’s go through our answer choices to discuss some additional details about this
molecule and see which of the provided statements does not describe a property of
ATP.
Answer choice (A) is accurate. Because ATP is used to power most processes inside cells, it needs to be easily
transported. It is a small molecule that diffuses into different parts of the cell. So this answer is incorrect.
Because ATP has charged phosphate groups, the molecule is polar and therefore soluble
in aqueous environments. This is beneficial because the internal environment of the cell, the cytoplasm, is
aqueous and where many reactions occur. So answer choice (B) is a correct statement and is therefore incorrect.
Answer choice (C) seems to be an incorrect statement. Because it’s polar, ATP is soluble in water and therefore would not be able to pass
through the phospholipid bilayer. Remember that the phospholipid bilayer is what composes the membranes of the
cell. It has a hydrophilic portion that has a strong affinity for water and a hydrophobic
portion that is strongly repelled by water. So the water-soluble ATP would not be able to cross this hydrophobic section. So answer choice (C) is an incorrect statement and is therefore correct. Before choosing this as our final answer, let’s look at the remaining choices.
Answer choice (D) is a correct statement, because a relatively small amount of energy
is released from ATP to power multiple processes. So this is incorrect.
And answer choice (E) is also a correct statement. When the phosphate bond in ATP is used for energy, it forms ADP or adenosine
diphosphate. This reaction is actually reversible. So ADP can be phosphorylated to produce ATP. This way ATP is renewable. So answer choice (C) is incorrect.
Therefore, the option that does not describe a property of ATP is given by answer
choice (C). It is an insoluble molecule that can pass easily through the phospholipid
bilayer.
