Admission Test for Dental Hygiene (ATDH) Practice

What is cytosol primarily composed of?

1. Proteins and enzymes

2. Cellular fluid

3. Cell organelles

4. Nucleic acids

The correct answer is: Cellular fluid

Cytosol is primarily composed of cellular fluid, which includes water, dissolved ions, small molecules, and large water-soluble molecules such as proteins. The cytosol serves as the site where many metabolic reactions occur and provides a medium that facilitates the movement of molecules around the cell. While proteins and enzymes are indeed present in the cytosol, they are not the primary component; rather, they are suspended within the cellular fluid. Cell organelles, such as mitochondria and the endoplasmic reticulum, are distinct structures within the cytoplasm and are not part of the composition of cytosol itself. Nucleic acids, like DNA and RNA, are mainly found within the cell's nucleus and are not significant components of the cytosol. Thus, the correct answer highlights the fundamental role of cytosol as the fluid part of the cytoplasm that supports the cell's internal environment and biochemical functions.