Structure of Cell in Biology
Biology is a study of living organisms or life as such. The study of life has been magnified with the invention of microscope which aided very much in the study of the basic components of life called Cells. Cells are the basic components and the building blocks of life. Their discovery in 1665 by English inventor and scientist, Robert Hooke made a revolution in biology and paved the way for scientific ways to be adopted in the field of biology.
All living organisms are made up of cells. A human body contains 100 million million cells in the body. Each cell is very small.
Structure of a cell:
The cell surface membrane:
The cell surface membrane is a very delicate layer surrounding the cell. It holds the cell together and plays an important role in controlling what enters into the cell and exits out of it. The cell surface membrane is made up of two very thin layers of fat combined with phosphate –a phospholipid, protein and carbohydrate are present too. If the cell surface membrane breaks, then the cell dies.
The nucleus is the essential ingredient in life itself. It contains the blueprint of life, the chromosomes and genes (DNA). The nucleus controls the various processes which take place inside a cell.
The cytoplasm transfers energy, makes things and stores food. Hundreds of chemical reactions take place inside it. Together, these reactions make up metabolism. Scattered about in the cytoplasm are what looks like little dots. The large dots are mitochondria. These are described as the power houses of cell. Their job is to supply energy.
Inside a typical plant cell:
- A plant cell, in addition to the cell surface membrane, the plant cell has a cell wall. It is made up of cellulose, a tough rubbery material.
- In the center of the cell there is a large cavity called vacuole, which is filled with a watery fluid called cell sap. This means that the cytoplasm is pushed towards the edge of the cell. The nucleus is suspended in the middle of the vacuole by fine strands of cytoplasm.
- The cytoplasm contains starch grains. This is how plants store food. The starch grains are equivalent to glycogen capsules found in animal cells.
- Many plant cells possess chloroplasts. These are located in the cytoplasm, and they contain the green pigment chlorophyll which is used in photosynthesis. Chloroplasts only occur in green parts of plants which are exposed to light. Roots and other underground structures lack them.
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