The cell membrane is composed of several different molecules, each listed below. What is the function of each?
- Phospholipid
- Cholesterol
- Proteins

Phospholipids provide barriers in cellular membranes to protect the cell, and they make barriers for the organelles within those cells. Phospholipids work to provide pathways for various substances across membranes.

Cholesterols main function is to maintain the integrity and fluidity of cell membranes and to serve as a precursor for the synthesis of substances that are vital for the organism including steroid hormones, bile acids, and vitamin D.

Protein has many roles in your body. It helps repair and build your body's tissues, allows metabolic reactions to take place and coordinates bodily functions. In addition to providing your body with a structural framework, proteins also maintain proper pH and fluid balance.