Actin fibers exist within a single cell and give the cell its shape through its constant interaction with myosin also present in cell. Chemical interactions 1. In muscle, the fusion of thousands of cells whose membranes dissolve to form synsytium Small molecules are also important to the cell, and these have different purposes. They include water, salts, sugars, lipids, amino acids, and nucleotides. Sugars serve as energy sources to the cell.
Excess energy is stored as fat in the form of lipids.
Some small amino acids can serve as neurotransmitters which move from cell to cell and transfer signals between nerves. It is important to understand how cells interact with one another. One such interaction is through electrical signals. Electrical signals transmitted between cells in the nervous system allow us to feel something. When we touch something, an electrical signal is sent through our nerve cells to our brain.