A cell is the basic unit of living organisms (both plants and animals)
that is capable of reproducing itself exactly. That is, there are
components within cells (organelles), but they do not reproduce themselves
independently of the cell(s) of which they are a part.
Lysosomes are tiny sacs filled with enzymes that enable the cell
to utilize its nutrients and are responsible for
destroying the cell after it has died. However, there are some
in which lysosomes begin to 'break-down' living cells.
Each lysosome is bounded by only a single membrane.
Lysosomes are particularly
abundant in liver and kidney cells.
See the Revision page about Cell
Structure for further information including a diagram of the
structure of a basic cell including lysosomes and
all the other organelles.