The Cell-an Introduction: Biology
Acellular organism
An organism not divided into cells.
Unicellular organism
An organism that only has one cell for its body.
Vacuole
Fluid filled sacs within the cytoplasm of a cell which are bound by a membrane. Some types contain food as it is being digested, others fill up most of the cell as in some plant cells.
Matter
That which occupies space and has mass.
Cell
The basic unit of lice according to the cell theory.
Organismal theory
The basic unit of life is the organism itself, which may be divided into cells for efficiency.
Cell theory
The idea of Schneider and Schwann that the basic unit of life is the cell, and that all living organisms are composed of cells.
Cytoplasm
The living substance of a cell, excluding the nucleus.
Cell wall
The outer covering found in plant cells outside of the plasma membrane. It is made of a double layer of cellulose, and serves to give strength and rigidity to the plant cell.
Epidermis
The outer layer of cells of the stems, roots, and leaves of plants.
Plasma membrane
The semipermeable membrane surrounding human and animal cells that is made up of phospholipids and proteins.
Nucleolous
The small, dark structures within the nucleus of a cell. They are thought to make r-RNA to construct the ribosomes.
Life cycle
The stages of a plant or an animal's life.
Organism
A functional living thing, unicellular or multicellular containing interrelated parts.
Calulerpa
A type of algae which is large enough to be seen without a microscope, but which is not divided into cells, although it has many nuclei. This organism supports the organismal theory.
Slime mold
A type of protist which has a stage in its life cycle when it is not divided into cells.
