The basic unit of life is the cell. Cells are the smallest structural and functional units that make up all living organisms, whether unicellular or multicellular
. Each cell is a discrete unit enclosed by a membrane, containing cytoplasm and organelles that perform specific functions necessary for life, such as energy production, protein synthesis, and reproduction
. Cells can exist independently as single-celled organisms (like bacteria) or as part of complex multicellular organisms (like humans), where they organize into tissues, organs, and systems
. The cell theory, developed in the 19th century, establishes that all living things are composed of cells, cells are the fundamental units of life, and all cells arise from pre-existing cells
. In summary:
- The cell is the fundamental unit of life.
- It carries out all essential life processes.
- Cells can be prokaryotic (without a nucleus) or eukaryotic (with a nucleus).
- Cells combine to form tissues, organs, and organisms in multicellular life forms
