Video Transcript
The equation provided summarizes
the primary reactants and products of aerobic cellular respiration. Glucose plus oxygen goes to carbon
dioxide plus water plus 38 ATP. Why is it beneficial for the cell
to break down glucose and store the energy in ATP molecules? (A) Because ATP is an insoluble
molecule, whereas glucose is a soluble molecule and so will break down in the
aqueous cell environment. (B) Because the breakdown of an ATP
molecule releases more energy than the breakdown of a glucose molecule. Or (C) because ATP provides an
easily accessible and immediate source of energy for the cell, whereas glucose takes
longer to break down and release energy.
So, what is ATP? ATP, or adenosine triphosphate, is
the molecule which stores chemical energy in living organisms. It allows cells to quickly access
the energy required for reactions and processes, with no waste products
produced.
During cellular respiration, the
energy stored in glucose is transferred to the bonds of ATP. As the diagram shows, ATP is made
up of an adenine base attached to a ribose sugar, which is attached to three
phosphate groups. The phosphate groups are connected
to each other by two energy rich bonds. When the cell requires energy, one
of these bonds can be hydrolyzed, releasing the energy stored and converting ATP to
ADP, or adenosine diphosphate. If further energy is required,
another bond can be hydrolyzed to produce adenosine monophosphate, releasing more
energy in the process.
Now that we’ve learnt a bit more
about ATP, let’s take a look at our answer choices and narrow down which best
describes the benefits of ATP.
First, we can eliminate answer
(A). ATP is a soluble molecule. This allows it to be easily
transported around the cell.
Next, we can eliminate answer
(B). The breakdown of glucose is how
cells get their energy. ATP molecules cannot store more
energy than is being released by the cells. In fact, ATP stores less energy
than a molecule of glucose. Refer to the equation in the
question; each molecule of glucose results in the production of around 38 ATP
molecules.
The correct answer is (C). ATP is small and soluble. It can be easily transported around
the cell and readily hydrolyzed to release energy. Glucose requires time and oxygen to
metabolize. It also produces waste
products.
So the correct answer is (C). It is beneficial for the cell to
break down glucose and store energy in ATP molecules because ATP provides an easily
accessible and immediate source of energy for the cell, whereas glucose takes longer
to break down and release energy.
