A cell is the basic unit of life. It consists of a mass of living matter called protoplasm, which is a mixture of many compounds arranged in an orderly manner. 70 to 90 percent of the protoplasm of a cell is water, whilst the rest are mineral salts and organic compounds such as carbohydrates, fats and proteins. The protoplasm of a cell consists mainly of three parts, namely the nucleus, cytoplasm and cell surface membrane.
The nucleus consists of a small spherical mass of denser protoplasm, the nucleoplasm, surrounded by a membrane called the nuclear envelope. It is found in the cytoplasm of the cell and controls the normal cell activities. Within the nucleus are the following:
Cytoplasm is the part that surrounds the nucleus. It forms the larger part of the human cell. In the cytoplasm we can find:
Cell surface membrane (Plasma membrane)
This partially permeable membrane controls substances that enter or leave the cell.
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