Living cells are the foundation of life. They are made up of complex biochemical structures and processes that enable them to react, respond, reproduce, metabolize and grow. All living cells share a set of common characteristics which make them distinct from non-living matter. These characteristics include having genetic information or DNA, being able to carry out metabolic functions such as producing energy through respiration and photosynthesis, exhibiting cellular organization including membrane-bound organelles with specialized functions and being able to replicate themselves by dividing into two daughter cells (known as mitosis).

One fundamental characteristic of living cells is the presence of deoxyribonucleic acid (DNA), which contains genetic information necessary for its survival. This information encodes proteins needed for cell growth and development. The double helix structure of DNA is composed of four nucleotides – adenine (A), thymine (T), guanine (G) and cytosine (C). Each strand contains one complementary sequence so that when two strands bond together they form a ladder shape in which A always pairs with T and G always pairs with C. In this way, cell replication occurs since each new daughter cell inherits an exact copy of the parent’s original genetic material containing the same instructions for its functioning. Additionally, DNA can be transcribed into messenger RNA that codes protein molecules necessary for cellular activities like enzyme production or gene regulation within a given organism’s genome..