A cell's daily operations are accomplished through ... To achieve this goal, cells organize reactions into various enzyme-powered pathways.

or enzyme activation, respectively. Because membrane receptors interact with both extracellular signals and molecules within the cell, they permit signaling molecules to affect cell function ...

For example, structural proteins maintain cell shape, akin to a skeleton, and they compose structural elements in connective tissues like cartilage and bone in vertebrates. Enzymes are another ...