What are life functions of a cell?

All cells and hence all living organisms show life functions that make them distinct from the non-living world. These include: 1.    Nutrition - the cell's ability to acquire food and resources for its maintenance and growth 2.    Metabolism - the cell's ability to utilise the acquired nutrients and a series of chemical reactions to survive. for example produce chemical energy ATP from acquired glucose. 3.    Hemostasis - the cell's ability to maintain a stable internal environment optimal for the processes it carries out. Usually this is achieved by the cell having a membrane or series of membranes on the outside (such as the plasma membrane) or inside (such as organelles). it has to be able to dispose its toxic waste through excretion. 4.    Response - the cell's ability to perceive external stimuli from its environment and produce an appropriate response. For example a unicellular organism migrating towards a food source. 5.    Growth - the cell's ability to increase in size and when the conditions are right, divide. Cells "get tired", worn out and damaged over time, hence their ability to grow and divide helps to sustain them as species. Interestingly, you are a "new person" every month as most of the cells in the skin, blood and liver have been replaced with new cells. 6.    Reproduction - the cells ability to produce new cells; either producing identical copies of itself (binary fission and mitosis) or produce gametes (meiosis)Each cell has to orchestrate a complex series of processes and reactions in order to sustain itself and reproduce. That is why there is a debate about whether viruses should be considered as living or non-living as they cannot perform these functions. They survive by attaching to a healthy cell to which they inject their genetic material and hijack the cell's life-function machinery.