Structure of a cell
The basic components of cell are cytoplasm, cell membrane, nucleus and organelles.
- The thin outer layer of the cell is called the cell membrane or the plasma membrane.
- It separates the cell and its contents from the surroundings.
- It protects the inner cell contents.
- It protects the cell and gives it a shape.
- It is selectively permeable and allows water, minerals and other necessary substances to pass through it.
- It controls what passes in and out of the cell
- Cell wall is present only in plant cells.
- It is an additional wall outside the cell membrane.
- It is thick wall made up of cellulose.
- The cell wall gives shape to the plant cell, offer protection and provide rigidity to the cell.
- The cell wall is important for plants since they do not have a skeleton for support and protection, nor they can move to escape environmental stress.
- The cytoplasm is a jelly-like substance that makes up most of the inside of the cell.
- The cytoplasm has the nucleus and various other cellular components within it.
- These components are called cell organelles.
- The nucleus is a spherical body present inside the cell. It is the control centre of the cell.
- The nucleus is surrounded by the nuclear membrane and the liquid present inside is called nucleoplasm.
- The nucleus and the cytoplasm together make up the protoplasm.
- A smaller spherical structure present inside the nucleus, called Nucleolus plays an important role in protein synthesis.
- The nucleus also has a thread-like network called chromatin.
- The chromatin organizes itself into rod-like structures when the cell has to divide. These rod-like structures are called chromosomes. They contain the DNA inside them. DNA has the genes that help in transfer of characteristics from parent to the offspring. Therefore, DNA forms the hereditary material in most organisms.
- Note: The nucleus and cytoplasm together make up the protoplasm.