CELL STRUCTURE AND ORGANIZATION - Topic 4 Biology Notes Form One
Plants and animals are made up of units called cells. The cells are microscopic in such a way that they cannot be seen by our naked eyes.
Some organisms like protozoa, diatoms and bacteria consist of one cell and are called single-celled or unicellular organisms.
Some are made up of many cells and are called multicellular organisms.
The cell structure of living things was first seen by Robert Hooke in 1667 when he examined fine slices of cork.
Robert Hooke believed that the cells were empty and that the cell wall and cell membrane were the most important parts of the cell but now cell contents are seen to be the most important ones.
Therefore a cell can be defined as the smallest unit of living things or a cell is a basic unit of life.
The Characteristics of the Cell
Characteristics of the cell include the following:
1. Cells are small microscopic structures which cannot be seen by our naked eyes.
2. Cells are capable of dividing by mitotic process or meiotic process.
3. Cells contain structures called organelles.
The cell theory
a. A cell is a basic unit of structure and function in living organisms.
b. New cells only come from pre-existing ones.
c. Cells contain structures called organelles.
The cell theories were proposed jointly by two scientists namely Schleiden, a Belgian botanist, in 1838 and Schwann, German Zoologist, in 1839.
CELL STRUCTURE AND ORGANIZATION - Topic 4 Biology Notes Form One