Video Transcript
The reactions involved in
metabolism can be divided into two broad categories: catabolism and anabolism. Which of the following best defines
catabolism? (A) Catabolism is the process by
which large molecules are broken down into smaller units. Or (B) catabolism is the process by
which large molecules are constructed from the joining of smaller units.
Each reaction that occurs in your
body contributes to your overall metabolism, which is the sum of all the chemical
reactions that occur within you to maintain life.
There are two main types of
metabolic reaction: anabolic reactions and catabolic reactions.
Anabolic reactions involve
constructing large molecules by forming bonds between their smaller subunits,
thereby joining them together. The formation of these bonds
requires an input of energy, which is supplied by breaking the high-energy bonds in
molecules of ATP.
In contrast, catabolic reactions,
which this question concerns, involve breaking the bonds in large, complex
molecules, breaking these molecules down into their smaller subunits. The breaking of bonds in catabolic
processes releases energy, which is temporarily stored in cells in the high-energy
bonds of ATP molecules. These high-energy bonds in ATP can
be quickly broken so that the energy they store can be easily accessed when needed,
for example, in an anabolic reaction.
Now we have enough information to
find the correct answer to this question, which asks us to find the best definition
for catabolism. The best definition is given by
answer option (A). Catabolism is the process by which
large molecules are broken down into smaller units.
