Protoplasm

In biology, protoplasm is the living substance inside the cell. At the simplest level, it is divisible into cytoplasm and nucleoplasm. It is also sometimes termed "bioplasm", (Beale: meaning the essential substance of living matter within a cell) and is distinct from non-living cell components lumped under "ergastic substances". Ergastic substances can occur in the protoplasm. In many plant cells most of the volume of the cell is not occupied by protoplasm, but by "tonoplast": a large water filled vacuole enclosed by a membrane.

The idea that protoplasm is divisible into a ground substance called "cytoplasm" and a structural body called the Cell nucleus, reflects the more primitive knowledge of cell structure that preceded the development of powerful microscope of organic and inorganic substances, mysteriously directed by the nucleus and controlled by the cell membrane. Today, it is known that the cytoplasm is structurally very complex, and that protoplasm is living because of the complexity of the "cytoplasmic organelles" and their careful separation and orchestration of multiple chemical processes.

Protoplasm exists in three forms: solid state, liquid state and sometimes a combined solid and liquid state.

Whether the protoplasm is in either of the three forms depends upon the physiological state of the cell.

History of the term

Charles Darwin and his 19th century contemporaries viewed "protoplasm" as the sole content of a cell, in other words, cells were nothing but simple blobs composed of "proto-plasm", a substance that had the ability of self replication. This simplified view of cell biology circumvented the problem of the origin of life that Darwin and others struggled with. However, that problem was later introduced in the 1950s when the complex molecular structure of DNA was discovered with following research into the complex biochemistry of living things.

The concept of protoplasm was perceived as the essence of life ("vita force"), being something nearly sacred, induplicable by man as it can evolve into quite a number of other living creatures.

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History of the term

See also