Why is the cell called the structural and functional unit of life?

Cell is called the structural Unit of life as all the organisms are made up of cells. Each Cell has to tendency to perform certain basic functions mainly due to its membrane and cytoplasmic organelles orientation which result in each cell having a particular structure and set of functions, Eg:- Some cells are oriented to perform in heart whereas some in  stomach.Hence a cell is called the structural and functional unit of life.