Which of the following is an example of catabolism?
Multiple Choice
A The increase in muscle tissue with exercise
B The formation of secretory proteins in the pancreas
C The breakdown of glucose in the cytoplasm and mitochondria
D The assembly of the cell membrane from precursor molecules
The correct answer and explanation is:
The correct answer is C) The breakdown of glucose in the cytoplasm and mitochondria.
Catabolism refers to metabolic processes that break down molecules into smaller units, often releasing energy in the process. The breakdown of glucose is a classic example of a catabolic pathway. During cellular respiration, glucose is broken down into pyruvate in the cytoplasm (through glycolysis), and further processed in the mitochondria, where it is eventually converted into carbon dioxide, water, and energy (in the form of ATP).
This catabolic process is crucial for providing the energy needed by cells to perform their various functions. The breakdown of glucose not only generates ATP but also produces smaller molecules, such as NADH and FADH2, which are used in further energy-producing pathways, like the electron transport chain.
In contrast:
- A) The increase in muscle tissue with exercise is an example of anabolism, as it involves the building of complex molecules (proteins, in this case) from simpler ones, requiring energy.
- B) The formation of secretory proteins in the pancreas is also anabolic because it involves the synthesis of proteins from amino acids, which requires energy input.
- D) The assembly of the cell membrane from precursor molecules is another example of anabolism since it involves building complex structures like phospholipid bilayers from smaller lipid molecules.
In summary, the breakdown of glucose (option C) is an example of catabolism, where larger molecules are broken down to release energy and generate smaller components for the cell’s use.